FIX: json decoder bug jdec was crashing when string had spaces

include/com/sequencer.h

@@ -31,7 +31,6 @@
 #ifndef TBX_COM_SEQUENCER_H_
 #define TBX_COM_SEQUENCER_H_
 
-
 #include <core/core.h>
 #include <core/crtp.h>
 #include <cont/range.h>
@@ -116,8 +115,9 @@ class sequencer {
             EXPECT,     //!< Expects data from implementation via get()
             OR_EXPECT,  //!< Expects data from implementation via get() in conjunction with previous EXPECT
             DETECT,     //!< Detects data into rx buffer without receiving them via contents()
-            OR_DETECT   //!< Detects data into rx buffer without receiving them via contents() in conjunction with
+            OR_DETECT,  //!< Detects data into rx buffer without receiving them via contents() in conjunction with
                         //!< previous DETECT
+            OTHERWISE   //!< An "else" path if the EXPECT[, OR_EXPECT[, OR_EXPECT ... ]] block timesout.
 
             //! \note
             //! The \c DETECT extra incoming channel serve the purpose of sneak into receive
@@ -347,6 +347,7 @@ class sequencer {
                        case control_t::OR_EXPECT:   skip_while = control_t::OR_EXPECT; break;
                        case control_t::DETECT:
                        case control_t::OR_DETECT:   skip_while = control_t::OR_DETECT; break;
+                       case control_t::OTHERWISE:   skip_while = control_t::OTHERWISE; break;
                    }
                    s = step;
                    while (script[++s].control == skip_while)
@@ -358,6 +359,17 @@ class sequencer {
            }
        }
 
+        template <size_t Steps>
+        size_t expect_end (const script_t<Steps>& script, size_t step) {
+            while ((++step < Steps) && (script[step].control == control_t::OR_EXPECT)) ;
+            return step;
+        }
+
+        template <size_t Steps>
+        size_t detect_end (const script_t<Steps>& script, size_t step) {
+            while ((++step < Steps) && (script[step].control == control_t::OR_DETECT)) ;
+            return step;
+        }
     //! @}
 
 
@@ -453,34 +465,52 @@ class sequencer {
                    case control_t::OR_EXPECT:
                        resp_size = get_(buffer);
                        if (resp_size) {
-                           size_t s = step ; do{
+                           for (size_t s = step ; s < expect_end(script, step) ; ++s) {
                                if (script[s].match != nullptr && script[s].match({buffer, resp_size}, script[s].token)) {
                                    handle_ (script[s].handler, {buffer, resp_size});
                                    std::tie(step, status) = action_ (script, s);
                                    break;
                                }
-                           } while ((++s < Steps) && (script[s].control == control_t::OR_EXPECT));
+                           }
+                       }
+                       if (record.timeout && (clock_() - mark) >= record.timeout) {
+                           size_t s = expect_end(script, step);
+                           if ((s < Steps) && (script[s].control == control_t::OTHERWISE)) {
+                               handle_ (script[s].handler, {buffer, resp_size});
+                               std::tie(step, status) = action_ (script, s);
+                           } else {
+                               return exit_error.value;
+                           }
                        }
-                       if (record.timeout && (clock_() - mark) >= record.timeout)
-                           return exit_error.value;
                        break;
 
                    case control_t::DETECT:
                    case control_t::OR_DETECT:
                        resp_size = contents_(buffer);
                        if (resp_size) {
-                           size_t s = step ; do {
+                           for (size_t s = step ; s < detect_end(script, step) ; ++s) {
                                if (script[s].match != nullptr && script[s].match({buffer, resp_size}, script[s].token)) {
                                    handle_ (script[s].handler, {buffer, resp_size});
                                    std::tie(step, status) = action_ (script, s);
                                    break;
                                }
-                           } while ((++s < Steps) && (script[s].control == control_t::OR_DETECT));
+                           }
+                       }
+                       if (record.timeout && (clock_() - mark) >= record.timeout) {
+                           size_t s = detect_end(script, step);
+                           if ((s < Steps) && (script[s].control == control_t::OTHERWISE)) {
+                               handle_ (script[s].handler, {buffer, resp_size});
+                               std::tie(step, status) = action_ (script, s);
+                           } else {
+                               return exit_error.value;
+                           }
                        }
-                       if (record.timeout && (clock_() - mark) >= record.timeout)
-                           return exit_error.value;
                        break;
 
+                   case control_t::OTHERWISE:
+                       handle_ (script[step].handler, {buffer, resp_size});
+                       std::tie(step, status) = action_ (script, step);
+                       break;
                } // switch (record.control)
 
            } while ( status == seq_status_t::CONTINUE);

include/cont/deque.h

@@ -34,7 +34,6 @@
 #include <core/core.h>
 #include <core/ring_iterator.h>
 #include <cont/range.h>
-
 #include <array>
 #include <atomic>
 
@@ -86,13 +85,18 @@ class deque {
         constexpr deque () noexcept :
             data_{},
             f{data_.data(), N},
-            r{data_.data()} { }
+            r{data_.data()} {
+                if constexpr (SemiAtomic)
+                    std::atomic_thread_fence(std::memory_order_release);
+            }
 
         //! fill contructor
         constexpr deque(const Data_t& value) noexcept {
             data_.fill(value);
             f = iterator(data_.data(), N);
             r = iterator(data_.data(), N);
+            if constexpr (SemiAtomic)
+                std::atomic_thread_fence(std::memory_order_release);
         }
 
         //! Initializer list contructor
@@ -100,7 +104,10 @@ class deque {
         constexpr deque(It&& ...it) noexcept :
             data_{{std::forward<It>(it)...}},
             f(data_.data(), N),
-            r(data_.data(), sizeof...(It)) { }
+            r(data_.data(), sizeof...(It)) {
+                if constexpr (SemiAtomic)
+                    std::atomic_thread_fence(std::memory_order_release);
+            }
 
         deque(const deque&) = delete;                   //!< No copies
         deque& operator= (const deque&) = delete;       //!< No copy assignments
@@ -132,10 +139,10 @@ class deque {
     public:
         //! \return The size of the deque. The items currently in queue.
         constexpr size_t size() noexcept {
-            return full() ? N: (r - f) -1;
+            return r - (f +1);
         }
         constexpr size_t size() const noexcept {
-            return full() ? N: (r - f) -1;
+            return r - (f +1);
         }
         //! \return The maximum size of the deque. The items the queue can hold.
         constexpr size_t max_size() noexcept { return N; }
@@ -144,11 +151,8 @@ class deque {
         //! \return True if the deque is empty
         constexpr bool   empty()    noexcept { return size() == 0 ? true : false; }
         //! \return True if the deque is full
-        constexpr bool   full()     noexcept {
-            if constexpr (SemiAtomic)
-                std::atomic_thread_fence(std::memory_order_acquire);
-            return (r == f) ? true : false;
-        }
+        constexpr bool   full()     noexcept { return size() == N ? true : false; }
+
     //! @}
 
     //! \name Member access
@@ -166,36 +170,26 @@ class deque {
         //! \param it   The item to push
         constexpr void push_front (const Data_t& it) noexcept {
             if (full())     return;
-            if constexpr (SemiAtomic)
-                std::atomic_thread_fence(std::memory_order_acquire);
-            *f-- = it;
-            if constexpr (SemiAtomic)
-                std::atomic_thread_fence(std::memory_order_release);
-        }
-        //! \brief      Extract an item from the front of the deque and remove it from the deque
-        //! \param it   The item to push
-        constexpr Data_t pop_front () noexcept {
-            if (empty())    return Data_t{};
-            if constexpr (SemiAtomic)
-                std::atomic_thread_fence(std::memory_order_acquire);
-            return *++f;
+            *f = it;
+            --f;        // keep this separate for thread safety
         }
         //! \brief      Push an item in the back of the deque
         //! \param it   The item to push
         constexpr void push_back (const Data_t& it) noexcept {
             if (full())     return;
-            if constexpr (SemiAtomic)
-                std::atomic_thread_fence(std::memory_order_acquire);
-            *r++ = it;
-            if constexpr (SemiAtomic)
-                std::atomic_thread_fence(std::memory_order_release);
+            *r = it;
+            ++r;        // keep this separate for thread safety
+        }
+        //! \brief      Extract an item from the front of the deque and remove it from the deque
+        //! \param it   The item to push
+        constexpr Data_t pop_front () noexcept {
+            if (empty())    return Data_t{};
+            return *++f;
         }
         //! \brief      Extract an item from the back of the deque and remove it from the deque
         //! \param it   The item to push
         constexpr Data_t pop_back () noexcept {
             if (empty())    return Data_t{};
-            if constexpr (SemiAtomic)
-                std::atomic_thread_fence(std::memory_order_acquire);
             return *--r;
         }
 

include/cont/edeque.h

@@ -191,21 +191,21 @@ class edeque : public deque<Data_t, N, SemiAtomic> {
         }
     //! @}
 
-    //!  \name Base class overwrites
+    //!  \name Base class uses and overwrites
     //! @{
         void push_front (const Data_t& it) noexcept {
             base_type::push_front(it);
             check_trigger_push_async_(it);
         }
+        void push_back (const Data_t& it) noexcept {
+            base_type::push_back(it);
+            check_trigger_push_async_(it);
+        }
         Data_t pop_front () noexcept {
             Data_t t = base_type::pop_front();
             check_trigger_pop_async_(t);
             return t;
         }
-        void push_back (const Data_t& it) noexcept {
-            base_type::push_back(it);
-            check_trigger_push_async_(it);
-        }
         Data_t pop_back () noexcept {
             Data_t t = base_type::pop_back();
             check_trigger_pop_async_(t);

include/core/ring_iterator.h

@@ -293,9 +293,14 @@ class ring_iterator<Iter_t, N, true> {
             return *this;
         }
         constexpr ring_iterator operator++(int) noexcept {
-            ring_iterator it = *this;
-            this->operator ++();
-            return it;
+            ring_iterator ret = *this;
+            Iter_t itnew, it = iter_.load(std::memory_order_acquire);
+            do {
+                itnew = it;
+                if (static_cast<size_t>(++itnew - base_) >= N)
+                    itnew = base_;
+            } while (!iter_.compare_exchange_weak(it, itnew, std::memory_order_acq_rel));
+            return ret;
         }
     //! @}
 
@@ -312,9 +317,14 @@ class ring_iterator<Iter_t, N, true> {
             return *this;
         }
         constexpr ring_iterator operator--(int) noexcept {
-            ring_iterator it = *this;
-            this->operator --();
-            return it;
+            ring_iterator ret = *this;
+            Iter_t itnew, it = iter_.load(std::memory_order_acquire);
+            do {
+                itnew = it;
+                if (--itnew < base_)
+                    itnew = base_ + N -1;
+            } while (!iter_.compare_exchange_weak(it, itnew, std::memory_order_acq_rel));
+            return ret;
         }
     //! @}
 

include/drv/cli_device.h

@@ -31,18 +31,15 @@
 #ifndef TBX_DRV_CLI_DEVICE_H_
 #define TBX_DRV_CLI_DEVICE_H_
 
-#define __cplusplus 201703L
-
 #include <core/core.h>
 #include <core/crtp.h>
 #include <cont/equeue.h>
-#include <cont/range.h>
 #include <com/sequencer.h>
 
 #include <cstring>
 #include <cstdlib>
-#include <algorithm>
 
+#include <algorithm>
 #include <utility>
 #include <atomic>
 
@@ -127,7 +124,8 @@ class cli_device
         //! Publish delimiter
         constexpr static char delimiter = Delimiter;
 
-        enum flush_type { keep =0, flush };
+        enum Flush_t { Keep =0, Flush };
+        enum Receive_t { Get =0, Detect };
 
         //! Required types for inetd async handler operation
         //! @{
@@ -250,7 +248,7 @@ class cli_device
          * \param token     Pointer to store the parsed tokens
          * \return          A (number of characters parsed, marker found) pair
          */
-        template <char Marker = '%'>
+        template <char Marker>
         std::pair<size_t, bool> parse_ (const char* expected, const string_view buffer, char* token) {
             do {
                 if (*expected == Marker) {
@@ -276,53 +274,23 @@ class cli_device
             return std::make_pair(0, false);
         }
 
-
-        /*!
-         * Analyze the response of a command based on \c expected.
-         *
-         * Tries to receive data with timeout and match them against expected string_view.
-         * For each Marker inside the expected string the value gets extracted, converted and
-         * copied to \c vargs pointer array.
-         *
-         * \param expected      The expected string view
-         * \param timeout       the timeout in CPU time
-         * \param vargs         Pointer to variable arguments array
-         * \param nargs         Size of variable arguments array
-         * \return
-         */
-        template<char Marker = '%', typename T>
-        bool response_ (const string_view expected, clock_t timeout, T* vargs, size_t nargs) {
-            char buffer[N], token[N], *pbuffer = buffer;
-
-            size_t v =0, sz =0;
-            for (auto ex = expected.begin() ; ex != expected.end() ;  ) {
-                clock_t mark = clock();                     // mark the time
-                while (sz <= 0) {                           // if buffer is empty get buffer with timeout
-                    sz = receive(buffer);
-                    pbuffer = buffer;
-                    if ((timeout != 0 )&& ((clock() - mark) >= timeout))
-                        return false;
-                }
-                // try to parse
-                auto [step, marker] = parse_<Marker> (ex, {pbuffer, sz}, token);
-                if (!step)
-                    return false;                           // discard buffer and fail
-
-                if (marker && v < nargs)
-                    extract_(token, vargs[v++]);
-
-                pbuffer += step;
-                sz      -= (step <= sz) ? step: sz;
-                ++ex;
-            }
-            return true;
-        }
     //! @}
 
     //! \name public functionality
     //! @{
     public:
 
+        //! Clears the incoming data buffer
+        void clear () noexcept {
+            rx_q.clear();
+            streams_.store(size_t(0), std::memory_order_release);
+        }
+
+        //! \return     Returns the size of the incoming data buffer
+        size_t size() noexcept {
+            return rx_q.size();
+        }
+
         /*!
          * \brief
          *   Transmit data to modem
@@ -373,14 +341,48 @@ class cli_device
             return 0;
         }
 
-        //! Clears the incoming data buffer
-        void clear () noexcept {
-            rx_q.clear();
-        }
+        /*!
+         * Analyze the response of a command based on \c expected.
+         *
+         * Tries to receive data via get() path with timeout and match them against expected string_view.
+         * For each Marker inside the expected string the value gets extracted, converted and
+         * copied to \c vargs pointer array.
+         *
+         * \param expected      The expected string view
+         * \param timeout       the timeout in CPU time
+         * \param vargs         Pointer to variable arguments array
+         * \param nargs         Size of variable arguments array
+         * \return
+         */
+        template<Receive_t Recv, char Marker, typename T>
+        bool response (const string_view expected, clock_t timeout, T* vargs, size_t nargs) {
+            char buffer[N], token[N], *pbuffer = buffer;
 
-        //! \return     Returns the size of the incoming data buffer
-        size_t size() noexcept {
-            return rx_q.size();
+            size_t v =0, sz =0;
+            for (auto ex = expected.begin() ; ex != expected.end() ;  ) {
+                clock_t mark = clock();                     // mark the time
+                while (sz <= 0) {                           // if buffer is empty get buffer with timeout
+                    if constexpr (Recv == Get)
+                        sz = receive(buffer);
+                    else
+                        sz = contents(buffer);
+                    pbuffer = buffer;
+                    if ((timeout != 0 )&& ((clock() - mark) >= timeout))
+                        return false;
+                }
+                // try to parse
+                auto [step, marker] = parse_<Marker> (ex, {pbuffer, sz}, token);
+                if (!step)
+                    return false;                           // discard buffer and fail
+
+                if (marker && v < nargs)
+                    extract_(token, vargs[v++]);
+
+                pbuffer += step;
+                sz      -= (step <= sz) ? step: sz;
+                ++ex;
+            }
+            return true;
         }
 
         /*!
@@ -390,7 +392,7 @@ class cli_device
          * This function executes 3 steps.
          *  - Clears the incoming buffer if requested by template parameter
          *  - Sends the command to device
-         *  - Waits to get the response and parse it accordingly to \c expected \see response_()
+         *  - Waits to get the response and parse it accordingly to \c expected \see response()
          *
          * The user can mark spots inside the expected string using the \c Marker ['%'] character.
          * These spots will be extracted to tokens upon parsing. If the user passes \c values parameters,
@@ -402,7 +404,7 @@ class cli_device
          * \param timeout   The timeout in CPU time (leave it for 0 - no timeout)
          * \param values    The value pointer arguments to get the converted tokens
          *
-         * \tparam Flush    Flag to indicate if we flush the buffer before command or not
+         * \tparam Flush    Flag to indicate if we Flush the buffer before command or not
          * \tparam Marker   The marker character
          * \tparam Ts       The type of the values to read from response marked with \c Marker
          * \warning         The types MUST be the same
@@ -419,31 +421,31 @@ class cli_device
          *    cli.command("AT+CREG?\r\n", "%%%OK\r\n", 1000);
          *
          *    // extract a number from response without timeout (blocking)
-         *    cli.command<flush>("AT+CREG?\r\n", "\r\n+CREG: 0,%\r\n\r\nOK\r\n", 0, &status);
+         *    cli.command<Flush>("AT+CREG?\r\n", "\r\n+CREG: 0,%\r\n\r\nOK\r\n", 0, &status);
          *
          *    // extract a number and discard the last 2 lines
-         *    cli.command<flush>("AT+CREG?\r\n", "\r\n+CREG: 0,%\r\n%%", 1000, &status);
+         *    cli.command<Flush>("AT+CREG?\r\n", "\r\n+CREG: 0,%\r\n%%", 1000, &status);
          *
          *    // discard first line, read the 2nd to str, discard the 3rd line.
          *    // expect the last to be "OK\r\n"
-         *    cli.command<flush>("AT+CREG?\r\n", "", 100000);
-         *    cli.command<keep>("", "%",  1000);
-         *    cli.command<keep>("", "%%", 1000, str);
-         *    cli.command<keep>("", "OK\r\n",  1000);
+         *    cli.command<Flush>("AT+CREG?\r\n", "", 100000);
+         *    cli.command<Keep>("", "%",  1000);
+         *    cli.command<Keep>("", "%%", 1000, str);
+         *    cli.command<Keep>("", "OK\r\n",  1000);
          * \endcode
          */
-        template<flush_type Flush =flush, char Marker = '%', typename ...Ts>
+        template<Receive_t Recv =Get, Flush_t Flsh =Flush, char Marker = '%', typename ...Ts>
         bool command (const string_view cmd, const string_view expected, clock_t timeout, Ts* ...values) {
             constexpr size_t Nr = sizeof...(Ts);
 
             front<typelist<Ts...>>* vargs[Nr] = {values...};        // read all args to local buffer
-            if constexpr (Flush == flush) {
+            if constexpr (Flsh == Flush) {
                 clear ();
             }
             if (transmit(cmd.data(), cmd.size()) != cmd.size())     // send command
                 return false;
             // parse the response and return the status
-            return response_<Marker>(expected, timeout, vargs, Nr);
+            return response<Recv, Marker>(expected, timeout, vargs, Nr);
         }
 
         /*!

include/drv/gpio.h

@@ -0,0 +1,107 @@
+/*!
+ * \file drv/gpio.h
+ * \brief
+ *      A STM32 gpio wrapper class
+ *
+ * \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
+ *
+ * <dl class=\"section copyright\"><dt>License</dt><dd>
+ * The MIT License (MIT)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ * </dd></dl>
+ */
+
+#ifndef TBX_DRV_GPIO_H_
+#define TBX_DRV_GPIO_H_
+
+#include <core/core.h>
+
+namespace tbx {
+
+    /*!
+     * CRTP class for gpio digital input-output.
+     *
+     * The derived class requirements are:
+     *  - bool read_impl ()
+     *  - void write_impl(bool)
+     *
+     * \tparam  Impl_t  The type of derived class
+     */
+    template <typename Impl_t>
+    class DigitalInOut {
+    public:
+            _CRTP_IMPL(Impl_t);
+
+        /*!
+         * \name Object lifetime
+         */
+        //! @{
+        protected:
+            DigitalInOut() noexcept = default;
+            ~DigitalInOut() = default;
+            DigitalInOut(const DigitalInOut&)             = delete;   //!< No copy constructions
+            DigitalInOut operator=(const DigitalInOut&)   = delete;   //!< No copies
+
+        //! @}
+
+        //! \name Public interface
+        //! @{
+        public:
+            //! Reads the state of the pin. This is true for both input and output pins.
+            //! \return     The state of the pin
+            bool read () noexcept { return impl().read_impl (); }
+            //! Write a new state to pin. If the pin is set for output, otherwise this state will remain
+            //! to pin registers and reflect to the pin state if we select output mode
+            void write (bool state) noexcept { impl().write_impl(state); }
+
+            //! Implicit conversion to bool for reading operations
+            operator bool () noexcept {
+                return read();
+            }
+            //! Stream from bool for write operations
+            DigitalInOut& operator<< (bool state) noexcept {
+                write(state);
+                return *this;
+            }
+            //! Right stream to bool for read operations
+            DigitalInOut& operator>> (bool& state) noexcept {
+                state = read();
+                return *this;
+            }
+        //! @}
+    };
+
+    /*!
+     * This definition enables the "data << pin" syntax for read operation
+     *
+     * \tparam Impl_t   The derived class type of the DigitalInOut
+     *
+     * \param lhs   Left hand site operand
+     * \param rhs   Right hand site operand
+     * \return      The read value
+     */
+    template<typename Impl_t>
+    bool operator<<(bool& lhs, DigitalInOut<Impl_t>& rhs) noexcept {
+        lhs = rhs.read();
+        return lhs;
+    }
+}
+
+#endif //#ifndef TBX_DRV_STM32GPIO_H_

include/drv/liquid_crystal.h

@@ -0,0 +1,536 @@
+/*!
+ * \file drv/liquid_crystal.h
+ * \brief
+ *      A liquid crystal display driver
+ *
+ * \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
+ *
+ * <dl class=\"section copyright\"><dt>License</dt><dd>
+ * The MIT License (MIT)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ * </dd></dl>
+ */
+
+#ifndef TBX_DRV_LIQUID_CRYSTAL_H_
+#define TBX_DRV_LIQUID_CRYSTAL_H_
+
+#include <core/core.h>
+#include <core/crtp.h>
+#include <utils/print.h>
+
+#include <type_traits>
+#include <ctime>
+
+namespace tbx {
+
+    /*!
+     * \class liquid_crystal
+     * \brief
+     *      A CRTP driver class for liquid crystal display with parallel interface,
+     *      based on Hitachi HD44780 (Samsung KS0066U, or compatible).
+     *
+     * The driver inherits from Print
+     * The Implementation requirements are:
+     *  - void bus_impl(data);          To set the 4bit/8bit bus
+     *  - void rs_pin_impl(state);      To set/clear RS pin
+     *  - void en_pin_impl(state);      To set/clear EN pin
+     *  - void power_pin_impl(state);   To set/clear PWR pin
+     *  - void bl_pin_impl(state);      To set/clear BackLight pin
+     *  - void delay_usec_impl(usec);   To provide delay in usec
+     *
+     * \tparam Impl_t       The derived class
+     * \tparam Lines        The lines of the LCD
+     * \tparam Columns      The coluns of the LCD
+     * \tparam BusSize      The LCD bus size (4 or 8 bits)
+     */
+    template <typename Impl_t, size_t Lines, size_t Columns, size_t BusSize =4>
+    class liquid_crystal : public Print<liquid_crystal<Impl_t, Lines, Columns, BusSize>, char>{
+        friend Print<liquid_crystal, char>;
+        _CRTP_IMPL(Impl_t);
+        static_assert((BusSize == 4) || (BusSize == 8), "BusSize must be either 4 or 8.");
+
+    public:
+        constexpr static size_t lines   = Lines;
+        constexpr static size_t columns = Columns;
+        /*!
+         * Public enumerator to be used as argument to the init() function.
+         * Selects the font size and thus the number of active lines
+         */
+        enum class FontSize :uint8_t { dots_5x8, dots_5x10 };
+    private:
+
+        // Commands
+        constexpr static uint8_t Cmd_cls        = 0x01;
+        constexpr static uint8_t Cmd_RetHome    = 0x02;
+        constexpr static uint8_t Cmd_EntryMode  = 0x04;
+        constexpr static uint8_t Cmd_DispCtrl   = 0x08;
+        constexpr static uint8_t Cmd_Shift      = 0x10;
+        constexpr static uint8_t Cmd_FunSet     = 0x20;
+        constexpr static uint8_t Cmd_SetGRamAddr= 0x40;
+        constexpr static uint8_t Cmd_SetDRamAddr= 0x80;
+
+        /*
+         *  Entry Mode Set -----> 0  0  0  0      0  1  I/D  S
+         *  ----------------------------------------------------
+         *  I/D = 1 Increment Curs
+         *        0 Decrement
+         *  S   = 1 Display shift
+         *        0 Not
+         */
+        constexpr static uint8_t Entry_Right    = 0x00;
+        constexpr static uint8_t Entry_Left     = 0x02;
+        constexpr static uint8_t Entry_ShiftInc = 0x01;
+        constexpr static uint8_t Entry_ShiftDec = 0x00;
+
+        /*
+         *  DispOnOffControll -->  0  0  0  0     1  D  C  B
+         *  -------------------------------------------------
+         *  D = Display On
+         *  C = Cursor On
+         *  B = Blinking On
+         */
+        constexpr static uint8_t Display_On     = 0x04;
+        constexpr static uint8_t Display_Off    = 0x00;
+        constexpr static uint8_t Cursor_On      = 0x02;
+        constexpr static uint8_t Cursor_Off     = 0x00;
+        constexpr static uint8_t Blink_On       = 0x01;
+        constexpr static uint8_t Blink_Off      = 0x00;
+
+        /*
+         *  Cursor/Display Shift --> 0  0  0  1   S/C R/L  x  x
+         *  ---------------------------------------------------
+         *  S/C = 1 Display Shift
+         *        0 Cursor Shift
+         *  R/L = 1 Shift Right
+         *        0 Shift left
+         */
+        constexpr static uint8_t DisMove_Display= 0x08;
+        constexpr static uint8_t DisMove_Cursor = 0x00;
+        constexpr static uint8_t DisMove_Right  = 0x04;
+        constexpr static uint8_t DisMove_Left   = 0x00;
+
+        /*
+         *  FunctionSet     ------>  0  0  1 DL   N   F   x  x
+         *  ---------------------------------------------------
+         *  DL = 1 8bit
+         *       0 4bit
+         *  N  = 1 2 lines
+         *       0 1 line
+         *  F  = 1 5x10 dots
+         *       0 5x8 dots
+         */
+        constexpr static uint8_t FunSet_8bitMode= 0x10;
+        constexpr static uint8_t FunSet_4bitMode= 0x00;
+        constexpr static uint8_t FunSet_2Line   = 0x08;
+        constexpr static uint8_t FunSet_1Line   = 0x00;
+        constexpr static uint8_t FunSet_5x10dots= 0x04;
+        constexpr static uint8_t FunSet_5x8dots = 0x00;
+
+        /*!
+         * \brief
+         *      Helper class to keep track of the display cursor. As we dont read the cursor
+         *      position on the display, in order to implement backspace operation we need to
+         *      keep track the cursor position manually.
+         */
+        struct Cursor {
+            uint8_t inc_x() noexcept {
+                if (++x_ > Columns)  x_ =1;
+                return x_;
+            }
+            uint8_t dec_x() noexcept {
+                if (--x_ < 1)        x_ =Columns;
+                return x_;
+            }
+            uint8_t inc_y () noexcept {
+                if (++y_ > max_lines) y_ =1;
+                return y_;
+            }
+            uint8_t dec_y () noexcept {
+                if (--y_ < 1)        y_ =max_lines;
+                return y_;
+            }
+            uint8_t operator++() noexcept { return inc_x(); }
+            uint8_t operator--() noexcept { return dec_x(); }
+            void set(uint8_t x, uint8_t y) noexcept {
+                x_ = x;
+                y_ = y;
+            }
+            uint8_t get_x() noexcept { return x_; }
+            uint8_t get_y() noexcept { return y_; }
+            void set_lines (uint8_t l) noexcept { max_lines = l; }
+        private:
+            uint8_t x_, y_;
+            uint8_t max_lines;
+        };
+    private:
+        //! \name Implementation requirements
+        //! @{
+        void BUS (uint8_t data)   { impl().bus_impl(data); }
+        void RS_Pin (bool state)  { impl().rs_pin_impl(state); }
+        void EN_Pin (bool state)  { impl().en_pin_impl(state); }
+        void PWR_Pin (bool state) { impl().power_pin_impl(state); }
+        void BL_Pin (bool state)  { impl().bl_pin_impl(state); }
+        void delay_usec(size_t usec) {
+            impl().delay_usec_impl(usec);
+        }
+        //! @}
+
+        //! \name Print interface requirements
+        //! @{
+        size_t write_impl (const char* str, size_t size) {
+            size_t ret =0;
+            while (*str && ret < size) {
+                putchar (*str++);
+                ++ret;
+            }
+            return ret;
+        }
+        size_t write_impl (const char ch) {
+            return (putchar(ch) == ch) ? 1:0;
+        }
+        //! @}
+
+    protected:
+        //! \name Object lifetime
+        //! @{
+        liquid_crystal() noexcept   = default;      //!< Construct from derived only
+        //~liquid_crystal()           = default;
+        liquid_crystal(const liquid_crystal&)               = delete;   //!< No copies
+        liquid_crystal& operator= (const liquid_crystal&)   = delete;   //!< No copies
+        //! @}
+
+    private:
+        //! Send enable pulse to display
+        void pulse_enable () {
+            EN_Pin(0);
+            delay_usec (2);     // time to settle BUS pin voltages
+            EN_Pin(1);
+            delay_usec (2);     // >450 [nsec]
+            EN_Pin(0);
+            delay_usec (50);    // > 37 [usec]
+        }
+
+        //! Writes 4/8bit data to display and pulse the EN pin
+        //! \param  data    The data to write
+        void write_bits (uint8_t data) {
+            if constexpr (BusSize == 4) BUS (data & 0x0F);
+            else                        BUS (data);
+            pulse_enable ();
+        }
+
+        /*!
+         * \brief
+         *      Sends commands or character to display by controlling RS pin
+         * \param data  The data to send
+         * \param mode  Character/command mode (RS pin state)
+         */
+        void send (uint8_t data, uint8_t mode) {
+            RS_Pin (mode);
+            if constexpr (BusSize == 4) {
+                write_bits (data >> 4);
+                write_bits (data & 0x0F);
+            } else {
+                write_bits (data);
+            }
+        }
+        //! Send a command to display
+        void command (uint8_t c)   { send(c, 0); }
+        //! Send a character to display
+        void character (uint8_t c) { send(c, 1); }
+
+    public:
+        //! \name Public API
+        //! @{
+
+        /*!
+         * \brief
+         *      Initialize the display. After construction the object is valid but reflects the init state
+         *      of display configuration. In order for the display to be functional it needs initialization.
+         *      So the user has to call this function. This function requires a settled environment, so usually
+         *      its called after main().
+         * \param mode      4bit or 8bit mode
+         * \param fontSize  5x8 or 5x10 dots font size.
+         */
+        void init (FontSize fontSize =FontSize::dots_5x8) {
+            disp_mode_    = disp_mode_init_;    // Set values to LCD's startup configuration
+            disp_control_ = disp_control_init_;
+            disp_function_=disp_function_init_;
+
+            // Read user configuration
+            if constexpr (BusSize == 4)
+                // note: keep this runtime, so the disp_function reflects lcd's configuration state
+                disp_function_ &= ~FunSet_8bitMode;
+            else
+                disp_function_ |= FunSet_8bitMode;
+
+            if (fontSize == FontSize::dots_5x10) {
+                disp_function_ |= FunSet_5x10dots;
+                disp_function_ &= ~FunSet_2Line;
+                cursor_.set_lines(Lines>>1);
+            } else {
+                disp_function_ &= ~FunSet_5x10dots;
+                disp_function_ |= FunSet_2Line;
+                cursor_.set_lines(Lines);
+            }
+
+            // start with All-zeros
+            BUS (0);  EN_Pin(0); RS_Pin(0); BL_Pin(0);
+
+            delay_usec(100000);
+            if constexpr (BusSize == 4) {
+                // 4bit BUS
+                write_bits (0x03);                      // 1t try
+                delay_usec(20000);
+                write_bits (0x03);                      // 2nd try
+                delay_usec(5000);
+                write_bits (0x03);                      // 3rd try
+                delay_usec(5000);
+                write_bits (0x02);                      // We set 4 bit interface
+                delay_usec (10000);
+            } else {
+                // 8bit BUS
+                write_bits (Cmd_FunSet | disp_function_);   // 1st try
+                delay_usec(20000);
+                write_bits (Cmd_FunSet | disp_function_);   // 2nd try
+                delay_usec(5000);
+                write_bits (Cmd_FunSet | disp_function_);   // 3rd try
+                delay_usec(5000);
+            }
+            command (Cmd_FunSet | disp_function_);      // Finally we set #lines and font size
+            delay_usec(5000);
+
+            command (Cmd_DispCtrl | Display_Off);   // Display off
+            delay_usec(5000);
+            command (Cmd_cls);                      // Clear screen
+            delay_usec(5000);
+            command (Cmd_EntryMode | disp_mode_);   // Entry mode set
+            delay_usec(5000);
+
+            command (Cmd_RetHome);                  // Return home
+            delay_usec(10000);
+            display(true);                          // Finally display On, done.
+            cursor_.set(1, 1);
+        }
+
+        //! Utility function to enable/disable power to display. This has an effect IFF there is a
+        //! power pin on the board
+        void power (bool en) {
+            PWR_Pin(en);
+        }
+
+        //! Utility function to enable/disable backlight. This has an effect IFF there is a
+        //! backlight pin on the board
+        void backlight (bool en) {
+            BL_Pin(en);
+        }
+
+        //! Utility function to send on/off command to display.
+        void display (bool en) {
+            if (en)     disp_control_ |= Display_On;
+            else        disp_control_ &= ~Display_On;
+
+            command (Cmd_DispCtrl | disp_control_);
+            delay_usec(100);
+        }
+
+        //! Utility function to enable/disable display cursor.
+        void cursor (bool en) {
+            if (en)     disp_control_ |= Cursor_On;
+            else        disp_control_ &= ~Cursor_On;
+
+            command (Cmd_DispCtrl | disp_control_);
+            delay_usec(100);
+        }
+
+        //! Utility function to enable/disable cursor blinking.
+        void blink (bool en) {
+            if (en)     disp_control_ |= Blink_On;
+            else        disp_control_ &= ~Blink_On;
+
+            command (Cmd_DispCtrl | disp_control_);
+            delay_usec(100);
+        }
+
+        //! Utility function to enable/disable autoscroll.
+        void autoscroll (bool en) {
+            if (en)     disp_mode_ |= Entry_ShiftInc;
+            else        disp_mode_ &= ~Entry_ShiftInc;
+
+            command (Cmd_EntryMode | disp_mode_);
+            delay_usec(100);
+        }
+
+        /*!
+         * \brief
+         *      Tool to set display cursor
+         * \param x     The column position (starting with 1)
+         * \param y     The line position (starting with 1 at the top of the display)
+         */
+        void set_cursor (uint8_t x, uint8_t y) {
+            uint8_t offset;
+            switch (y) {
+               default:
+               case 1: offset = 0x0;   break;
+               case 2: offset = 0x40;  break;
+               case 3: offset = 0x0  + Columns; break;
+               case 4: offset = 0x40 + Columns; break;
+            }
+            command( Cmd_SetDRamAddr | offset | (x-1));
+            cursor_.set(x, y);
+        }
+
+        //! Utility function to set left to right entry mode.
+        //! \note
+        //!     This is the default
+        void set_left_to_right () {
+            disp_mode_ |= Entry_Left;
+            command (Cmd_EntryMode | disp_mode_);
+            delay_usec(100);
+        }
+
+        //! Utility function to set right to left entry mode.
+        void set_right_to_left () {
+            disp_mode_ &= ~Entry_Left;
+            command (Cmd_EntryMode | disp_mode_);
+            delay_usec(100);
+        }
+
+        //! Command to scroll display left one position
+        void scroll_left () {
+            command (Cmd_Shift | DisMove_Display | DisMove_Left);
+        }
+
+        //! Command to scroll display right one position
+        void scroll_right () {
+            command (Cmd_Shift | DisMove_Display | DisMove_Right);
+        }
+
+        //! Clears the display and return home
+        void clear() {
+            command (Cmd_cls);
+            cursor_.set(1, 1);
+            delay_usec(2000);
+        }
+
+        //! return home without clearing the display
+        void home() {
+            command (Cmd_RetHome);
+            cursor_.set(1, 1);
+            delay_usec(2000);
+        }
+
+        /*!
+         * \brief
+         *      Create custom character and store it to LCD.
+         * \param location  The location to store the character [0..7] allowed
+         * \param charmap   The character map buffer with the font
+         */
+        void create_char (uint8_t location, uint8_t charmap[]) {
+            location &= 0x7;        // we only have 8 locations 0-7
+            command(Cmd_SetGRamAddr | (location << 3));
+            for (size_t i=0; i<8; ++i) {
+                character(charmap[i]);
+            }
+        }
+
+        /*!
+         * \brief
+         *    Send an ascii character to liquid crystal display.
+         * \param  ch     the character to send
+         * \return the character send.
+         *
+         * \note
+         *    This is the driver's "putchar()" functionality to glue.
+         *    Tailor this function to redirect stdout to display.
+         */
+        int putchar (int ch) {
+            // LCD Character dispatcher
+            switch (ch) {
+                case 0:
+                    // don't send null termination to device
+                    break;
+                case '\n':
+                    cursor_.inc_y();
+                    set_cursor (1, cursor_.get_y());
+                    break;
+                case '\r':
+                    set_cursor (1, cursor_.get_y());
+                    break;
+                case '\v':
+                    home ();
+                    break;
+                case '\f':
+                    clear();
+                    break;
+                case '\b':
+                    --cursor_;
+                    set_cursor (cursor_.get_x(), cursor_.get_y());
+                    character (' ');
+                    --cursor_;
+                    set_cursor (cursor_.get_x(), cursor_.get_y());
+                    break;
+                default:
+                    character (ch);
+                    ++cursor_;
+                    break;
+            }
+            //ANSI C (C99) compatible mode
+            return ch;
+        }
+        //! @}
+
+    private:
+        //! \name Data members
+        //! @{
+
+        //! The init entry mode of the display after power up
+        static constexpr uint8_t disp_mode_init_    = Entry_Left | Entry_ShiftDec;
+        //! The init control mode of the display after power up
+        static constexpr uint8_t disp_control_init_ = Display_Off | Cursor_Off | Blink_Off;
+        //! The init function set of the display after power up
+        static constexpr uint8_t disp_function_init_= FunSet_8bitMode | FunSet_1Line | FunSet_5x8dots;
+
+        Cursor cursor_{};
+        uint8_t disp_mode_ {disp_mode_init_};
+        uint8_t disp_control_ {disp_control_init_};
+        uint8_t disp_function_ {disp_function_init_};
+        /*!
+         * \note
+         *  When the display powers up, it is configured as follows:
+         *  1. Display clear
+         *  2. Function set: 0x10
+         *     DL = 1; 8-bit interface data
+         *     N = 0; 1-line display
+         *     F = 0; 5x8 dot character font
+         *  3. Display on/off control: 0x00
+         *     D = 0; Display off
+         *     C = 0; Cursor off
+         *     B = 0; Blinking off
+         *  4. Entry mode set: 0x02
+         *     I/D = 1; Increment by 1
+         *     S = 0; No shift
+         */
+
+        //! @}
+    };
+
+}
+
+#endif /* TBX_DRV_LIQUID_CRYSTAL_H_ */

include/drv/sd_spi.h

@@ -0,0 +1,720 @@
+/*!
+ * \file drv/sd_spi.h
+ * \brief
+ *      SD card driver using SPI interface
+ *
+ * \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
+ *
+ * <dl class=\"section copyright\"><dt>License</dt><dd>
+ * The MIT License (MIT)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ * </dd></dl>
+ */
+
+#ifndef TBX_DRV_SD_SPI_H_
+#define TBX_DRV_SD_SPI_H_
+
+#include <core/core.h>
+#include <core/crtp.h>
+
+//#include <drv/diskio.h>
+
+#include <ctime>
+#include <utility>
+
+namespace tbx {
+
+/*!
+ *
+ * http://elm-chan.org/docs/mmc/mmc_e.html
+ *
+ * CRTP requirements
+ *  bool WP_impl ();                // write protect,      true => write protect
+ *  bool CD_impl ();                // check disk present, true => present
+ *  void CS_impl (bool select);     // Chip select,        true => select
+ *  void PWR_impl(bool state);      // SD power,           true => power the card
+ *  data_type SPI_rw_impl (data_type);      // SPI read-write functionality
+ *  bool SPI_set_clk_impl(uint32_t clk);    // SPI set clock functionality
+ *  clock_t clock_impl();           // get system's CPU time
+ */
+template <typename Impl_t>
+class sd_card {
+    _CRTP_IMPL(Impl_t);
+
+    using data_type = uint8_t;
+
+    // Driver settings
+    constexpr static clock_t SD_WaitTimeout = 500;      // 500 [CPU time]
+    constexpr static clock_t SD_PowerTimeout= 250;      // 250 [CPU time]
+    constexpr static clock_t SD_RxTimeout   = 100;      // 100 [CPU time]
+    constexpr static clock_t SD_InitTimeout = 2000;     // 2000 [CPU time]
+    constexpr static uint32_t MaxInitClock  = 400000;   // 400000 [Hz]
+
+    // MMC/SDC definitions
+    constexpr static data_type CMD_MSB      = 0x40;
+    constexpr static data_type CMD_CRC_LSB  = 0x01;
+
+    constexpr static data_type CMD0         = (CMD_MSB | 0);    //!< GO_IDLE_STATE
+    constexpr static data_type CMD1         = (CMD_MSB | 1);    //!< SEND_OP_COND (MMC)
+    constexpr static data_type CMD8         = (CMD_MSB | 8);    //!< SEND_IF_COND
+    constexpr static data_type CMD9         = (CMD_MSB | 9);    //!< SEND_CSD
+    constexpr static data_type CMD10        = (CMD_MSB | 10);   //!< SEND_CID
+    constexpr static data_type CMD12        = (CMD_MSB | 12);   //!< STOP_TRANSMISSION
+    constexpr static data_type CMD16        = (CMD_MSB | 16);   //!< SET_BLOCKLEN
+    constexpr static data_type CMD17        = (CMD_MSB | 17);   //!< READ_SINGLE_BLOCK
+    constexpr static data_type CMD18        = (CMD_MSB | 18);   //!< READ_MULTIPLE_BLOCK
+    constexpr static data_type CMD23        = (CMD_MSB | 23);   //!< SET_BLOCK_COUNT (MMC)
+    constexpr static data_type CMD24        = (CMD_MSB | 24);   //!< WRITE_BLOCK
+    constexpr static data_type CMD25        = (CMD_MSB | 25);   //!< WRITE_MULTIPLE_BLOCK
+    constexpr static data_type CMD55        = (CMD_MSB | 55);   //!< APP_CMD
+    constexpr static data_type CMD58        = (CMD_MSB | 58);   //!< READ_OCR
+
+    constexpr static data_type ACMD13       = (0xC0 + 13);      //!< SD_STATUS (SDC)
+    constexpr static data_type ACMD23       = (0xC0 + 23);      //!< SET_WR_BLK_ERASE_COUNT (SDC)
+    constexpr static data_type ACMD41       = (0xC0 + 41);      //!< SEND_OP_COND (SDC)
+
+    constexpr static data_type R1_READY_STATE      = 0x00;      //!< status for card in the ready state
+    constexpr static data_type R1_IDLE_STATE       = 0x01;      //!< status for card in the idle state
+    constexpr static data_type R1_ILLEGAL_COMMAND  = 0x04;      //!< status bit for illegal command
+    constexpr static data_type DATA_START_BLOCK    = 0xFE;      //!< start data token for read or write single block
+    constexpr static data_type STOP_TRAN_TOKEN     = 0xFD;      //!< stop token for write multiple blocks
+    constexpr static data_type WRITE_MULTIPLE_TOKEN= 0xFC;      //!< start data token for write multiple blocks
+    constexpr static data_type DATA_RES_MASK       = 0x1F;      //!< mask for data response tokens after a write block operation
+    constexpr static data_type DATA_RES_ACCEPTED   = 0x05;      //!< write data accepted token
+
+    // MMC card type flags (MMC_GET_TYPE)
+    //! \note
+    //! These types are compatible with FatFS types
+    constexpr static data_type CT_NONE      = 0x00;
+    constexpr static data_type CT_MMC       = 0x01;             //!< MMC ver 3
+    constexpr static data_type CT_SD1       = 0x02;             //!< SD ver 1
+    constexpr static data_type CT_SD2       = 0x04;             //!< SD ver 2
+    constexpr static data_type CT_SDC       = (CT_SD1|CT_SD2);  //!< SD
+    constexpr static data_type CT_BLOCK     = 0x08;             //!< Block addressing
+
+public:
+
+    enum status_t : uint8_t {
+        ST_OK         =0,
+        ST_NOINIT    = 1,
+        ST_NODISK    = 2,
+        ST_WRPROTECT = 3,
+        ST_ERROR     = 4
+    };
+
+    enum ioctl_cmd {
+        // Fatfs compatibility
+        IOCTL_SYNC              =0,     //!< Flush disk cache (for write functions)
+        IOCTL_GET_SECTOR_COUNT  =1,     //!< Get media size (for only f_mkfs())
+        IOCTL_GET_SECTOR_SIZE   =2,     //!< Get sector size (for multiple sector size (_MAX_SS >= 1024))
+        IOCTL_GET_BLOCK_SIZE    =3,     //!< Get erase block size (for only f_mkfs())
+        IOCTL_ERASE_SECTOR      =4,     //!< Force erased a block of sectors (for only _USE_ERASE)
+
+        // Generics
+        IOCTL_POWER             =5,     //!< Get/Set power status
+        IOCTL_LOCK              =6,     //!< Lock/Unlock media removal
+        IOCTL_EJECT             =7,     //!< Eject media
+        IOCTL_FORMAT            =8,     //!< Create physical format on the media
+
+        // SD/MMC specific
+        IOCTL_MMC_GET_TYPE      =10,    //!< Get card type
+        IOCTL_MMC_GET_CSD       =11,    //!< Get CSD
+        IOCTL_MMC_GET_CID       =12,    //!< Get CID
+        IOCTL_MMC_GET_OCR       =13,    //!< Get OCR
+        IOCTL_MMC_GET_SDSTAT    =14,    //!< Get SD status
+    };
+
+public:
+    sd_card() :
+        status{ST_NOINIT} { }
+
+    sd_card(const sd_card&)             = delete;
+    sd_card& operator=(const sd_card&)  = delete;
+
+private:
+
+    /*!
+     * \brief
+     *    Calculate the maximum data transfer rate per one data line
+     *    from the CSD.
+     *    TRAN_SPEED is the CSD[103..96]
+     *
+     *    TRAN_SPEED bit code
+     * ---------------------------------------------------
+     *    2:0     | transfer rate unit
+     *            | 0=100kbit/s, 1=1Mbit/s, 2=10Mbit/s,
+     *            | 3=100Mbit/s, 4... 7=reserved
+     *  ---------------------------------------------------
+     *    6:3     | time value
+     *  --------------------------------------------------
+     *    7       | Reserved
+     *
+     * \param      csd  Pointer to CSD array 128bit.
+     * \return     The maximum spi baud rate.
+     */
+    uint32_t csd2bautrate (data_type *csd) {
+        data_type  brmul = 0;
+        uint32_t br = 100000;     // 100Kbit
+
+        // Mask [2..0] bits of TRAN_SPEED
+        brmul = csd[3] & 0x07;
+        while (brmul--)
+            br *= 10;
+        return br;
+    }
+
+    void delay (clock_t t) {
+        clock_t mark = impl().clock_impl();
+        while (impl().clock_impl() - mark < t)
+            ;
+    }
+
+    /*!
+     * \brief Check if SD Card is present.
+     * \return        The sd card present status
+     *    \arg  false   Is NOT present
+     *    \arg  true    Is present.
+     */
+    bool is_present () {
+        return impl().CD_impl();
+    }
+
+    /*!
+     * \brief Check if SD Card is write protected.
+     * \return        The write protect status
+     *    \arg  false   Is NOT write protected
+     *    \arg  true    Is write protected.
+     */
+    bool is_write_protected () {
+        return impl().WP_impl();
+    }
+
+    /*!
+     * \brief Powers up or down the SD Card.
+     * \param   on    On/Off flag.
+     * \return        The new power state state
+     */
+    bool power (bool on) {
+        impl().PWR_impl(on);
+        return pwr_flag = on;
+    }
+
+    /*!
+     * \brief Check if SD Card is powered.
+     * \return        The power status
+     *    \arg  false The drive is not powered
+     *    \arg  true  The drive is powered
+     */
+    bool power () { return pwr_flag; }
+
+    /*!
+     * \brief Chip-select control
+     * \param   state   True to Select, false to de-select.
+     */
+    void select() {
+        spi_tx(0xFF);
+        impl().CS_impl(false);
+        spi_tx(0xFF);
+    }
+
+    /*!
+     * \brief De-select SD Card and release SPI bus
+     * \return        None.
+     */
+    void release () {
+        spi_tx(0xFF);
+        impl().CS_impl(true);
+        spi_tx(0xFF);
+    }
+
+    /*!
+     * \brief Transmit a byte to SD/MMC via SPI
+     * \param   data  The data to send to the SPI bus.
+     */
+    void spi_tx (data_type data) {
+        impl().SPI_rw_impl (data);
+    }
+
+    /*!
+     * \brief Receive a byte to SD/MMC via SPI.
+     * \return        The data received from SPI bus.
+     */
+    data_type spi_rx () {
+        return impl().SPI_rw_impl (0xFF);
+    }
+
+    /*!
+     * \brief Keep calling spi_rx until response \c resp.
+     *
+     * \param  resp     the response we wait for
+     * \param  timeout  timeout for the operation
+     * \return
+     *    \arg  true  Ready
+     *    \arg  false NOT ready.
+     */
+    bool spi_wait_for (data_type resp, clock_t timeout) {
+        data_type res;
+        clock_t mark = impl().clock_impl();
+
+        do
+           res = spi_rx ();
+        while ((res != resp) && ((impl().clock_impl() - mark) < timeout));
+
+        return (res == resp);
+    }
+
+    bool activate (bool state) {
+        if (state) {
+            power(true);                    // power on with delay
+            delay (SD_PowerTimeout);
+            impl().CS_impl(1);              // make sure CS is high
+            for (size_t i=0 ; i<10 ; ++i)   // 80 dummy clocks with DI high
+                spi_tx(0xFF);
+            status = ST_NOINIT;             // mark the status
+        }
+        else {
+            power(false);                   // power off
+            impl().CS_impl(0);              // keep CS pin voltage low
+            status = ST_NOINIT;             // mark the status
+        }
+        return state;
+    }
+
+    /*!
+     * \brief
+     *    Receive a data packet from MMC/SD
+     *
+     * \param   buffer  Pointer to data buffer to store received data
+     * \param   n       Byte count (must be multiple of 4)
+     * \return          The operation status
+     *    \arg  false   Fail
+     *    \arg  true    Success.
+     */
+    bool rx_datablock (data_type* buffer, size_t n) {
+
+        if (! spi_wait_for(DATA_START_BLOCK, SD_RxTimeout))
+            return false;
+
+        /*!
+         * Receive the data block into buffer and make sure
+         * we receive multiples of 4
+         */
+        n += (n%4) ? 4-(n%4):0;
+        for ( ; n>0 ; --n)
+           *buffer++ = spi_rx ();
+
+        spi_rx ();  // Discard CRC
+        spi_rx ();
+        return true;
+    }
+
+    /*!
+     * \brief
+     *    Transmit a data block (512bytes) to MMC/SD
+     *
+     * \param   buffer  Pointer to 512 byte data block to be transmitted
+     * \param   token   Data/Stop token
+     * \return          The operation status
+     *    \arg  false   Fail
+     *    \arg  true    Success.
+     */
+    bool tx_datablock (const data_type* buffer, data_type token) {
+        if (!spi_wait_for(0xFF, SD_WaitTimeout))
+            return false;
+
+        spi_tx(token);              // transmit data token
+        if (token != STOP_TRAN_TOKEN) {
+            // if its data token, transmit the 512 byte block
+            size_t cnt = 512;
+            do
+                spi_tx(*buffer++);
+            while (--cnt);
+            spi_tx(0xFF);           // CRC (Dummy)
+            spi_tx(0xFF);
+            data_type r = spi_rx(); // Receive data response
+            if ((r & DATA_RES_MASK) != DATA_RES_ACCEPTED) // If not accepted, return with error
+                return false;
+        }
+        return true;
+    }
+
+    /*!
+     * \brief
+     *    Send a command packet to SD/MMC and return the response
+     *
+     * \param   cmd     Command byte
+     * \param   arg     Argument
+     * \return          The response as operation status
+     */
+    data_type command (data_type cmd, uint32_t arg) {
+        data_type n, r;
+
+        if (cmd & 0x80) {
+           /*!
+            * SD_ACMD<n> is the command sequence of CMD55-SD_CMD<n>
+            */
+           cmd &= 0x7F;
+           r = command (CMD55, 0);
+           if (r > 1)
+               return r;
+        }
+
+        // Send command packet
+        spi_tx (cmd);                   // Start + Command index
+        spi_tx ((data_type)(arg>>24));  // Argument [31..24]
+        spi_tx ((data_type)(arg>>16));  // Argument [23..16]
+        spi_tx ((data_type)(arg>>8));   // Argument [15..8]
+        spi_tx ((data_type)arg);        // Argument [7..0]
+
+        if (cmd == CMD0)      n = 0x94; // Valid CRC for CMD0(0)
+        else if (cmd == CMD8) n = 0x86; // Valid CRC for CMD8(0x1AA)
+        else                   n = 0x00;
+        spi_tx (n | CMD_CRC_LSB);
+
+        // Receive command response
+        if (cmd == CMD12)
+           spi_rx ();    // Skip a stuff byte when stop reading
+
+        // Wait for a valid response in timeout of 0xFF attempts
+        size_t nn = 0xFF;
+        do
+           r = spi_rx ();
+        while ((r & 0x80) && --nn);
+
+        return r;       // Return with the response value
+    }
+
+    bool do_command_until (data_type done, data_type cmd, uint32_t arg, clock_t timeout) {
+        clock_t mark = impl().clock_impl();
+        data_type ret;
+        do
+            ret = command (cmd, arg);
+        while (ret != done && impl().clock_impl() - mark < timeout);
+        return ret == done;
+    }
+
+public:
+    bool get_CSD (data_type* csd) {
+        bool ret = false;
+        select();                                                           // select card's CS
+        if (command (CMD9, 0) == R1_READY_STATE && rx_datablock (csd, 16))  // READ_CSD
+            ret = true;
+        release();                                                          // release card's CS
+        return ret;
+    }
+
+    bool get_CID (data_type* cid) {
+        bool ret = false;
+        select();                                                           // select card's CS
+        if (command (CMD10, 0) == R1_READY_STATE && rx_datablock (cid, 16)) // READ_CID
+            ret = true;
+        release();                                                          // release card's CS
+        return ret;
+    }
+
+    bool get_OCR (data_type* ocr) {
+        bool ret = false;
+        select();                                                           // select card's CS
+        // Receive OCR as an R3 response (4 bytes)
+        if (command (CMD58, 0) == 0) {   // READ_OCR
+            for (size_t n = 0; n < 4; ++n)
+                *ocr++ = spi_rx ();
+            ret = true;
+        }
+        release();                                                          // release card's CS
+        return ret;
+    }
+
+//    bool get_SDSTAT (data_type* sdstat) {
+//        bool ret = false;
+//        select();                                                           // select card's CS
+//        if (command (ACMD13, 0) == 0) {  // SD_STATUS
+//           spi_rx ();
+//           if (rx_datablock (sdstat, 64))
+//              ret = true;
+//        }
+//        release();                                                          // release card's CS
+//        return ret;
+//    }
+
+    bool sync () {
+        select();                                       // select card's CS
+        bool st = spi_wait_for(0xFF, SD_WaitTimeout);   // flush
+        release();                                      // release card's CS
+        return st;
+    }
+
+    size_t sector_count() {
+        size_t ret =0;
+        data_type csd[16];
+
+        select();                                       // select card's CS
+        if (get_CSD(csd)) {
+            if ((csd[0] >> 6) == 1) {
+                // SDC version 2.00
+                size_t csize = csd[9] + ((uint16_t)csd[8] << 8) + 1;
+                ret = csize << 10;
+            }
+            else {
+                // SDC version 1.XX or MMC
+                uint8_t n = (csd[5] & 15) + ((csd[10] & 128) >> 7) + ((csd[9] & 3) << 1) + 2;
+                size_t csize = (csd[8] >> 6) + ((uint16_t)csd[7] << 2) + ((uint16_t)(csd[6] & 3) << 10) + 1;
+                ret = csize << (n - 9);
+            }
+        }
+        release();                                      // release card's CS
+        return ret;
+    }
+
+    size_t sector_size() const { return 512; }
+
+    size_t block_size() {
+        size_t ret =0;
+        data_type csd[16];
+
+        select();                                       // select card's CS
+        if (card_type & CT_SD2) {
+            // SDC version 2.00
+            if (command (ACMD13, 0) == R1_READY_STATE) {
+                spi_rx ();                              // Read SD status
+                if (rx_datablock (csd, 16)) {           // Read partial block
+                    for (size_t n = 64 - 16; n; n--)    // Purge trailing data
+                        spi_rx ();
+                    ret = 16UL << (csd[10] >> 4);
+                }
+            }
+        }
+        else {
+            // SDC version 1.XX or MMC
+            if (get_CSD(csd)) {                         // Read CSD
+                if (card_type & CT_SD1)                 // SDC version 1.XX
+                    ret = (((csd[10] & 63) << 1) + ((uint16_t)(csd[11] & 128) >> 7) + 1) << ((csd[13] >> 6) - 1);
+                else                                    // MMC
+                    ret = ((uint16_t)((csd[10] & 124) >> 2) + 1) * (((csd[11] & 3) << 3) + ((csd[11] & 224) >> 5) + 1);
+            }
+        }
+        release();                                      // release card's CS
+        return ret;
+    }
+
+    /*!
+     * \brief
+     *    De-Initialize SD Drive.
+     * \return  None
+     */
+    void deinit () {
+        card_type   = data_type{};
+        status      = status_t{};
+        activate (0);   // finally power off the card
+    }
+
+    /*!
+     * \brief
+     *    Initialize SD Drive.
+     *
+     * \return  The status of the operation
+     *    \arg  false   On error.
+     *    \arg  true    On success.
+     */
+    bool init () {
+        uint32_t clk;
+        data_type ocr[4], csd[16];
+
+        clk = 400000;                       // Start at lower clk
+        impl().SPI_set_clk_impl(clk);
+
+        activate (0);                       // Initially power off the card
+        if (!is_present()) {                // check for presence
+            status = ST_NODISK;
+            return false;
+        }
+        activate (1);                       // activate and wait for PowerTimeout delay
+
+        select();                           // select card
+        data_type type = CT_NONE;
+
+        if (command (CMD0, 0) == R1_IDLE_STATE) {   // Command to enter Idle state
+            if (command (CMD8, 0x1AA) == 1) {       // check SD version
+                // SDHC
+                for (size_t n=0 ; n<4 ; ++n)                // Get trailing return value of R7 response
+                    ocr[n] = spi_rx ();
+                if (ocr[2] == 0x01 && ocr[3] == 0xAA) {
+                    // Wait for leaving idle state (ACMD41 with HCS bit)
+                    bool st = do_command_until(R1_READY_STATE, ACMD41, 1UL << 30, SD_InitTimeout);
+
+                    if (st && get_OCR(ocr))
+                        type = (ocr[0] & 0x40) ? CT_SD2 | CT_BLOCK : CT_SD2;
+                }
+            } else {
+                data_type cmd;
+                // SDSC or MMC
+                if (command (ACMD41, 0) <= 1) {  // SDSC
+                    type = CT_SD1; cmd = ACMD41;
+                } else { // MMC
+                    type = CT_MMC; cmd = CMD1;
+                }
+                // Wait for leaving idle state (ACMD41 || CMD1)
+                bool st = do_command_until(R1_READY_STATE, cmd, 0, SD_InitTimeout);
+                // On failure, set R/W block length to 512 (For FAT compatibility)
+                if (!st || command (CMD16, 512) != R1_READY_STATE)
+                    type = CT_NONE;
+            }
+        }
+        card_type = type;
+        release ();    // Initialization ended
+
+        if (type != CT_NONE) {
+            // Success
+            get_CSD(csd);
+            clk = csd2bautrate(csd);
+            impl().SPI_set_clk_impl(clk);
+            status = ST_OK;
+            return true;
+        }
+        else {
+            activate(0);
+            return false;
+        }
+    }
+
+    status_t get_status () const { return status; }
+
+    /*!
+     * \brief
+     *    Read Sector(s)
+     *
+     * \param   sector Start sector number (LBA)
+     * \param   buf    Pointer to the data buffer to store read data
+     * \param   count  Sector (512 bytes) count (1..255)
+     * \return  The status of the operation
+     *    \arg  false       On error.
+     *    \arg  true        On success.
+     */
+    bool read (size_t sector, data_type *buf, size_t count) {
+
+        if (status != ST_OK)    return false;
+
+        if (!(card_type & CT_BLOCK))                        // Convert to byte address if needed
+            sector *= 512;
+        select();
+        if (count == 1) {                                   //Single block read
+            if (command (CMD17, sector) == 0)
+                if (rx_datablock (buf, 512))
+                    count = 0;
+        }
+        else {                                              // Multiple block read
+            if (command (CMD18, sector) == 0) {
+                do {
+                    if (!rx_datablock (buf, 512))
+                        break;
+                    buf += 512;
+                } while (--count);
+                command (CMD12, 0);                 // STOP_TRANSMISSION
+            }
+        }
+       release ();
+       return (count == 0);
+    }
+
+    /*!
+     * \brief
+     *    Write Sector(s)
+     *
+     * \param   sector Start sector number (LBA)
+     * \param   buf    Pointer to the data to be written
+     * \param   count  Sector(512 bytes) count (1..255)
+     * \return  The status of the operation
+     *    \arg  false       On error.
+     *    \arg  true        On success.
+     */
+    bool write (size_t sector, const data_type *buf, size_t count) {
+
+       if (!count)              return false;
+       if (status != ST_OK)     return false;
+
+       if (!(card_type & CT_BLOCK))                         // Convert to byte address if needed
+           sector *= 512;
+
+       select();
+       if (count == 1) {                                    // Single block write
+           if ((command (CMD24, sector) == 0) && tx_datablock (buf, 0xFE))
+               count = 0;
+       } else {                                             // Multiple block write
+           if (card_type & CT_SDC)
+               command (ACMD23, count);
+           if (command (CMD25, sector) == 0) {
+               do {
+                   if (!tx_datablock (buf, WRITE_MULTIPLE_TOKEN))
+                       break;
+                   buf += 512;
+               } while (--count);
+               if (!tx_datablock (0, STOP_TRAN_TOKEN))      // STOP token
+                   count = 1;
+           }
+       }
+       release ();
+       return (count == 0);
+    }
+
+    bool ioctl (ioctl_cmd cmd, void* buffer) {
+        switch (cmd) {
+            // SD/MMC specific
+            case IOCTL_MMC_GET_TYPE:    *(data_type*)buffer = card_type;    return true;
+            case IOCTL_MMC_GET_CSD:     return get_CSD ((data_type*)buffer);
+            case IOCTL_MMC_GET_CID:     return get_CID ((data_type*)buffer);
+            case IOCTL_MMC_GET_OCR:     return get_OCR ((data_type*)buffer);
+            case IOCTL_MMC_GET_SDSTAT:  return false;
+
+            // Generic
+            case IOCTL_POWER:
+                switch (*(data_type*)buffer) {
+                    case 0: *((data_type*)buffer+1) = (data_type)activate(0); return true;
+                    case 1: *((data_type*)buffer+1) = (data_type)activate(0); return true;
+                    case 2: *((data_type*)buffer+1) = (data_type)power();     return true;
+                    default: return false;
+                }
+                break;
+            case IOCTL_LOCK:
+            case IOCTL_EJECT:
+            case IOCTL_FORMAT:
+                return false;
+
+            // FatFS compatibility
+            case IOCTL_SYNC:            return sync();
+            case IOCTL_GET_SECTOR_COUNT:return (*(size_t*) buffer = sector_count() != 0);
+            case IOCTL_GET_SECTOR_SIZE: return (*(size_t*) buffer = sector_size() != 0);
+            case IOCTL_GET_BLOCK_SIZE:  return (*(size_t*) buffer = block_size() != 0);
+            case IOCTL_ERASE_SECTOR:    return false;
+
+            default:
+                return false;
+        }
+    }
+
+private:
+    data_type   card_type{};
+    status_t    status{};
+    bool        pwr_flag{};
+
+};
+
+} // namespace tbx
+
+#endif /* TBX_DRV_SD_SPI_H_ */

include/tbx.h

@@ -0,0 +1,50 @@
+/*!
+ * \file tbx.h
+ * \brief
+ *     Main tbx header
+ *
+ * \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
+ *
+ * <dl class=\"section copyright\"><dt>License</dt><dd>
+ * The MIT License (MIT)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ * </dd></dl>
+ */
+#ifndef TBX_H_
+#define TBX_H_
+
+#include <com/sequencer.h>
+
+#include <cont/deque.h>
+#include <cont/edeque.h>
+#include <cont/queue.h>
+#include <cont/equeue.h>
+
+#include <utils/json.h>
+#include <utils/shared.h>
+#include <utils/print.h>
+#include <utils/timer_delay.h>
+
+#include <drv/cli_device.h>
+#include <drv/liquid_crystal.h>
+#include <drv/gpio.h>
+#include <drv/sd_spi.h>
+
+#endif /* TBX_H_ */

include/utils/json.h

@@ -0,0 +1,224 @@
+/*!
+ * \file files.h
+ * \brief
+ *      File functionality header
+ *
+ * \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
+ *
+ * <dl class=\"section copyright\"><dt>License</dt><dd>
+ * All Rights Reserved.
+ *
+ * NOTICE:  All information contained herein is, and remains
+ * the property of Christos Choutouridis. The intellectual
+ * and technical concepts contained herein are proprietary to
+ * Christos Choutouridis and are protected by copyright law.
+ * Dissemination of this information or reproduction of this material
+ * is strictly forbidden unless prior written permission is obtained
+ * from Christos Choutouridis.
+ * </dd></dl>
+ */
+#ifndef JSON_H_
+#define JSON_H_
+
+#include <cstddef>
+#include <cstdlib>
+#include <cstring>
+#include <cctype>
+#include <type_traits>
+#include <string_view>
+#include <array>
+
+using size_t = std::size_t;
+
+struct jpair_t {
+    std::string_view key;
+    std::string_view value;
+};
+
+template<size_t N>
+struct json_dec_t {
+
+    using string_view = std::string_view;
+
+    json_dec_t(const char* buffer, size_t size) noexcept :
+    buffer_(buffer, size), valid_(true) {
+        enum state_t {
+            ST=0, KEY, COLON, VALUE, SP
+        } state = ST;
+
+        size_t pairs =0;
+        char* begin = nullptr;
+        int s =0;
+        bool str_value = false;     // flag to indicate the value is string
+
+        for (size_t i=0 ; i<size ; ++i) {
+            switch (state) {
+                case ST:
+                    if (std::isspace(buffer[i]))
+                        continue;   // skip white space
+                    if (buffer[i] == '{')
+                        state = KEY;
+                    break;
+
+                case KEY:
+                    if (pairs >= N) {
+                        valid_ = false;
+                        break;
+                    }
+                    if (std::isspace(buffer[i]))
+                        continue;   // skip white space
+                    if (buffer[i] == '\"') {
+                        if (!begin)
+                            begin = (char*)&buffer[i+1];
+                        else {
+                            s = (char*)&buffer[i] - begin;
+                            if (s > 0)
+                                pairs_[pairs].key = std::string_view{begin, (size_t)s};
+                            else
+                                pairs_[pairs].key = std::string_view{};
+                            begin =nullptr;
+                            s =0;
+                            state = COLON;
+                        }
+                    }
+                    else if (buffer[i] == '}')
+                        return;
+                    break;
+
+                case COLON:
+                    if (std::isspace(buffer[i]))
+                        continue;   // skip white space
+                    if (buffer[i] == ':')
+                        state = VALUE;
+                    else {
+                        valid_ = false;
+                        return;
+                    }
+                    break;
+
+                case VALUE:
+                    if (pairs >= N) {
+                        valid_ = false;
+                        break;
+                    }
+                    if (!begin && std::isspace(buffer[i]))          // consume pre-spaces
+                        continue;
+                    else if (!begin && !std::isspace(buffer[i])) {  // first character
+                        if (buffer[i] == '\"') {
+                            begin = (char*)&buffer[i+1];
+                            str_value = true;
+                        }
+                        else {
+                            begin = (char*)&buffer[i];
+                            str_value = false;
+                        }
+                    }
+                    else if (begin) {
+                        if (str_value && (buffer[i] == '\"')) {
+                            s  = (char*)&buffer[i] - begin;
+                            if (s > 0)
+                                pairs_[pairs].value = std::string_view{begin, (size_t)s};
+                            else
+                                pairs_[pairs].value = std::string_view{};
+                            ++pairs;
+                            begin =nullptr;
+                            s =0;
+                            state = SP;
+                        }
+                        else if (!str_value && (std::isspace(buffer[i]) || buffer[i] == ',' || buffer[i] == '}')) {
+                            s  = (char*)&buffer[i] - begin;
+                            if (s > 0)
+                                pairs_[pairs].value = std::string_view{begin, (size_t)s};
+                            else
+                                pairs_[pairs].value = std::string_view{};
+                            ++pairs;
+                            begin =nullptr;
+                            s =0;
+                            if (std::isspace(buffer[i]))
+                                state = SP;
+                            else if (buffer[i] == ',')
+                                state = KEY;
+                            else if (buffer[i] == '}')
+                                return;
+                        }
+                    }
+                    break;
+
+                case SP:
+                    if (std::isspace(buffer[i]))
+                        continue;   // skip white space
+                    else if (buffer[i] == ',')
+                        state = KEY;
+                    else if (buffer[i] == '}')
+                        return;
+                    else {
+                        valid_ = false;
+                        return;
+                    }
+                    break;
+            }
+        }
+    }
+    template<typename T>
+    T get (const char* key) {
+        T t{};
+        for (auto& it : pairs_) {
+            if (it.key.compare(key) == 0) {
+                extract_(it.value, &t);
+                break;
+            }
+        }
+        return t;
+    }
+    bool is_valid() const { return valid_; }
+
+private:
+    /*!
+     * Convert the text pointed by \c str to a value and store it to
+     * \c value. The type of conversion is deduced by the compiler
+     * \tparam  T       The type of the value
+     * \param str       pointer to string with the value
+     * \param value     pointer to converted value
+     */
+    void extract_(std::string_view str, bool* value) {
+        *value = (
+            !std::strncmp(str.data(), "true", str.size()) ||
+            !std::strncmp(str.data(), "True", str.size()) ||
+            !std::strncmp(str.data(), "TRUE", str.size()) ||
+            !std::strncmp(str.data(), "1", str.size())
+        ) ? true : false;
+    }
+    void extract_(std::string_view str, int* value) {
+        *value = std::atoi(str.data());
+    }
+    void extract_(std::string_view str, unsigned int* value) {
+        *value = (unsigned int)std::atoi(str.data());
+    }
+    void extract_(std::string_view str, long* value) {
+        *value = std::atol(str.data());
+    }
+    void extract_(std::string_view str, unsigned long* value) {
+        *value = (unsigned long)std::atol(str.data());
+    }
+    void extract_(std::string_view str, double* value) {
+        *value = std::atof(str.data());
+    }
+    void extract_(std::string_view str, char** value) {
+        *value = (char*)str.data();
+    }
+    void extract_(std::string_view str, string_view* value) {
+        *value = str;
+    }
+    //! Specialization (as overload function) to handle void* types
+    void extract_ (const char* str, void* value) noexcept {
+        (void)*str; (void)value;
+    }
+private:
+    std::string_view        buffer_;
+    std::array<jpair_t, N>  pairs_;
+    bool                    valid_;
+};
+
+
+
+#endif /* JSON_H_ */

include/utils/print.h

@@ -0,0 +1,314 @@
+/*!
+ * \file utils/print.h
+ * \brief
+ *      A CRTP base class to provide print interface
+ *
+ * \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
+ *
+ * <dl class=\"section copyright\"><dt>License</dt><dd>
+ * The MIT License (MIT)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ * </dd></dl>
+ */
+
+#ifndef TBX_UTILS_PRINT_H_
+#define TBX_UTILS_PRINT_H_
+
+#include <core/core.h>
+#include <core/crtp.h>
+
+#include <cstring>
+#include <math.h>
+#include <string_view>
+#include <type_traits>
+#include <utility>
+#include <limits>
+
+namespace tbx {
+
+    /*!
+     * \class Print
+     * \brief
+     *      A CRTP print interface
+     *
+     * Requirements:
+     *  - size_t write_impl(const Char_t* buffer, size_t size) : Return the number of \c Char_t written
+     *  - size_t write_impl(const Char_t ch) : Return the number of \c Char_t written (normally one).
+     *
+     * \tparam Impl_t       The derived type
+     * \tparam Char_t       The char type to use
+     */
+    template <typename Impl_t, typename Char_t>
+    class Print {
+        _CRTP_IMPL(Impl_t);
+
+    public:
+        using value_type        = Char_t;
+        using pointer_type      = Char_t*;
+        using iterator_type     = Char_t*;
+        using const_iterator_type = const Char_t*;
+        using difference_type   = std::ptrdiff_t;
+        using size_type         = size_t;
+        using str_view_t        = std::basic_string_view<Char_t>;
+
+        //! Enumerator for number base formating
+        enum class Base {
+            BIN =2, OCT =8, DEC =10, HEX =16
+        };
+
+    private:
+        //! \name CRTP requirements
+        //! @{
+        size_t write_(const Char_t* buffer, size_t size) {
+            return impl().write_impl(buffer, size);
+        }
+        size_t write_(const Char_t ch) {
+            return impl().write_impl(ch);
+        }
+        //! @}
+
+    protected:
+        Print() noexcept = default;     //!< Construct from derived only
+
+    private:
+        //! Helper tool to convert strong enums to their underlying type
+        template <typename E>
+        constexpr typename std::underlying_type_t<E> value(E e) noexcept {
+            return static_cast<typename std::underlying_type_t<E>>(e);
+        }
+
+        size_t print_unsigned(unsigned long n, Base base);  // integer conversion base tool
+        size_t print_double(double number, uint8_t digits); // double conversion base tool
+
+    public:
+        /*!
+         * \brief
+         *      Prints a string view
+         * \param str   The string view to print
+         * \return      The number of printed \c Char_t
+         */
+        size_t print(const str_view_t str) {
+            return write_(str.data(), str.size());
+        }
+
+        /*!
+         * \brief
+         *      Prints a string
+         * \param str   Pointer to string to print
+         * \return      The number of printed \c Char_t
+         */
+        size_t print(const Char_t* str) {
+            if (str == nullptr)
+                return 0;
+            return write_(str, std::strlen(str));
+        }
+
+        /*!
+         * \brief
+         *      Prints a buffer of size \c size. If there is a null termination
+         *      before the end of the buffer, prints up to termination.
+         *
+         * \param str       Pointer to string buffer to print
+         * \param size      The size of buffer
+         * \return      The number of printed \c Char_t
+         */
+        size_t print(const Char_t* str, size_t size) {
+            if (str == nullptr)
+                return 0;
+            return write_(str, size);
+        }
+
+        /*!
+         * \brief
+         *      Prints a \c Char_t
+         * \param ch    The Char_t to print
+         * \return      The number of printed \c Char_t
+         */
+        size_t print(Char_t ch) {
+            return write_ (ch);
+        }
+
+        /*!
+         * \brief
+         *      Convert and print a long.
+         * \param n     The number to print
+         * \param base  The number base to use for conversion.
+         * \return      The number of printed \c Char_t
+         */
+        size_t print(long n, Base base =Base::DEC) {
+            size_t cnt =0;
+            if (n < 0) {
+                n = -n;
+                cnt = write_ ('-');
+            }
+            return cnt + print_unsigned((unsigned long)n, base);
+        }
+
+        /*!
+         * \brief
+         *      Convert and print an int.
+         * \param n     The number to print
+         * \param base  The number base to use for conversion.
+         * \return      The number of printed \c Char_t
+         */
+        size_t print(int n, Base base= Base::DEC) {
+            return print ((long)n, base);
+        }
+
+        /*!
+         * \brief
+         *      Convert and print an unsigned long.
+         * \param n     The number to print
+         * \param base  The number base to use for conversion.
+         * \return      The number of printed \c Char_t
+         */
+        size_t print(unsigned long n, Base base= Base::DEC) {
+            return print_unsigned ((unsigned long)n, base);
+        }
+
+        /*!
+         * \brief
+         *      Convert and print an unsigned int.
+         * \param n     The number to print
+         * \param base  The number base to use for conversion.
+         * \return      The number of printed \c Char_t
+         */
+        size_t print(unsigned int n, Base base= Base::DEC) {
+            return print_unsigned ((unsigned long)n, base);
+        }
+
+        /*!
+         * \brief
+         *      Convert and print adouble
+         * \param n         The number to print
+         * \param digits    The number of decimal digits to print
+         * \return          The number of printed \c Char_t
+         */
+        size_t print(double n, uint8_t digits = 2) {
+            return print_double (n, digits);
+        }
+
+        /*!
+         * \brief
+         *      Perfect forwarder to print functionality with a new line termination
+         * \tparam Ts   The types of parameters
+         * \param args  The arguments to pass
+         * \return      The number of printed \c Char_t
+         */
+        template <typename ...Ts>
+        size_t println(Ts&& ...args) {
+            size_t r = print (std::forward<Ts>(args)...);
+            r += write_ ('\n');
+            return r;
+        }
+    };
+
+    /*!
+     * \brief
+     *      Converts and prints an unsigned long
+     *
+     * \tparam Impl_t       The derived type
+     * \tparam Char_t       The char type to use
+     *
+     * \param n     The number to print
+     * \param base  The number base to use
+     * \return      The number of printed \c Char_t
+     */
+    template <typename Impl_t, typename Char_t>
+    size_t Print<Impl_t, Char_t>::print_unsigned(unsigned long n, Base base) {
+        Char_t buf[8 *sizeof(Char_t) * sizeof(long) + 1]; // Assumes 8-bit chars plus zero byte.
+        Char_t *str = &buf[sizeof(buf) - 1];
+
+        *str = '\0';
+
+        do {
+            Char_t c = n % value(base);
+            n /= value(base);
+
+            *--str = c < 10 ? c + '0' : c + 'A' - 10;
+        } while(n);
+
+        return write_(str, std::strlen(str));
+    }
+
+    /*!
+     * \brief
+     *      Converts and prints a double
+     *
+     * \note
+     *  Internally, this implementation uses a long to store the integer part of the number.
+     *  Thus overflows for numbers bigger than std::numeric_limits<long>::max() / min().
+     *  For these numbers it prints "ovf" instead.
+     *
+     * \tparam Impl_t       The derived type
+     * \tparam Char_t       The char type to use
+     *
+     * \param n         The number to print
+     * \param digits    The number of decimal digits to print
+     * \return          The number of printed \c Char_t
+     */
+    template <typename Impl_t, typename Char_t>
+    size_t Print<Impl_t, Char_t>::print_double(double number, uint8_t digits)  {
+        size_t n = 0;
+
+        if (std::isnan(number))     return print("nan");
+        if (std::isinf(number))     return print("inf");
+        if (number > (double)std::numeric_limits<long>::max())
+            return print ("ovf");
+        if (number < (double)std::numeric_limits<long>::min())
+            return print ("-ovf");
+
+        // Handle negative numbers
+        if (number < 0.0) {
+            n += write_ ('-');
+            number = -number;
+        }
+
+        // Round correctly so that print(1.999, 2) prints as "2.00"
+        double rounding = 0.5;
+        for (uint8_t i=0; i<digits; ++i)
+            rounding /= 10.0;
+
+        number += rounding;
+
+        // Extract the integer part of the number and print it
+        unsigned long int_part = (unsigned long)number;
+        double remainder       = number - (double)int_part;
+        n += print(int_part);
+
+        // Print the decimal point, but only if there are digits beyond
+        if (digits > 0) {
+            n += print('.');
+        }
+
+        // Extract digits from the remainder one at a time
+        while (digits-- > 0) {
+            remainder *= 10.0;
+            unsigned int toPrint = (unsigned int)(remainder);
+            n += print(toPrint);
+            remainder -= toPrint;
+        }
+
+        return n;
+    }
+
+
+}
+#endif /* TBX_UTILS_PRINT_H_ */

include/utils/shared.h

@@ -0,0 +1,107 @@
+/*!
+ * \file utils/shared.h
+ * \brief
+ *      A CRTP base class to provide acquire/release functionality for shared resources
+ *      without handle pointers.
+ *
+ * \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
+ *
+ * <dl class=\"section copyright\"><dt>License</dt><dd>
+ * The MIT License (MIT)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ * </dd></dl>
+ */
+
+#ifndef TBX_UTILS_SHARED_H_
+#define TBX_UTILS_SHARED_H_
+
+#include <core/core.h>
+#include <core/crtp.h>
+
+#include <utility>
+
+namespace tbx {
+
+/*!
+ * A CRTP base class to provide acquire/release functionality for shared resources
+ * without handle pointers.
+ *
+ * \example
+ * \code
+ * class GPIOClock : public shared<GPIOClock> {
+ *     friend shared<GPIOClock>;
+ *     void acquire_impl() { // HAL enable gpio clock }
+ *     void release_impl() { // HAL disable gpio clock }
+ * };
+ * GPIOClock clk;
+ * class Pin {
+ *     Pin() {
+ *         clk.acquire();
+ *         // init pin
+ *     }
+ *     ~Pin() {
+ *         // de-init pin
+ *         clk.release();
+ *     }
+ * };
+ * \endcode
+ *
+ * \tparam Impl_t   The derived class type
+ */
+template <typename Impl_t>
+class shared {
+        _CRTP_IMPL(Impl_t);
+        int count {};   //!< acquisition counter
+
+    protected:
+        shared() noexcept               = default;
+        shared(const shared&)           = delete;   //!< No copies
+        shared operator=(const shared&) = delete;   //!< No copies
+
+    public:
+        /*!
+         * Acquires the recourse. If it is the first call to acquire the resource we actually acquire it.
+         * Otherwise we just keep track of how many acquisition have made.
+         *
+         * \tparam Ts   The types of possible arguments
+         * \param args  Possible arguments to pass to acquire_impl() of derived class
+         */
+        template <typename ...Ts>
+        void acquire (Ts&&... args) {
+            if (!count++)   impl().acquire_impl(std::forward<Ts>(args)...);
+        }
+        /*!
+         * Release the recourse. On every call we decrease the count of acquisitions. If we reach zero
+         * we actually release the resource.
+         *
+         * \tparam Ts   The types of possible arguments
+         * \param args  Possible arguments to pass to release_impl() of derived class
+         */
+        template <typename ...Ts>
+        void release (Ts&&... args) noexcept {
+            if (--count <= 0) {
+                impl().release_impl(std::forward<Ts>(args)...);
+                count =0;
+            }
+        }
+};
+
+}
+#endif /* TBX_UTILS_SHARED_H_ */

include/utils/timer_delay.h

@@ -0,0 +1,333 @@
+/*!
+ * \file utils/timer_delay.h
+ * \brief
+ *      A CRTP timer delay utility
+ *
+ * \copyright Copyright (C) 2021 Christos Choutouridis <christos@choutouridis.net>
+ *
+ * <dl class=\"section copyright\"><dt>License</dt><dd>
+ * The MIT License (MIT)
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ * </dd></dl>
+ */
+
+#ifndef TBX_UTILS_TIMER_DELAY_H_
+#define TBX_UTILS_TIMER_DELAY_H_
+
+#include <core/core.h>
+#include <core/crtp.h>
+
+#include <type_traits>
+
+namespace tbx {
+
+    /*!
+     * \class timer_delay
+     * \brief
+     *      A CRTP hw timer based, delay implementation.
+     *
+     * CRTP requirements:
+     *  - int set_frequency_impl (size_t freq, Counter_t ticks)
+     *    Initialize and start the hw timer with tick frequency \c freq and reload value \c ticks
+     *  - volatile Counter_t* get_value_ptr_impl (Counter_t discard)
+     *    Return a pointer to hw timer counter value register. The \c discard argument should discarded.
+     *
+     * \tparam Impl_t       The derived class
+     * \tparam Counter_t    The hw timer's type
+     */
+    template <typename Impl_t, typename Counter_t>
+    class timer_delay {
+        _CRTP_IMPL(Impl_t);
+        using value_t  = volatile Counter_t;
+        using marker_t = std::make_signed_t<std::remove_cv_t<Counter_t>>;
+
+    //! \name CRTP requirements
+    //! @{
+    private:
+        int set_frequency (size_t freq, Counter_t ticks) {
+            return impl().set_frequency_impl(freq, ticks);
+        }
+        volatile Counter_t* get_value_ptr (Counter_t discard = Counter_t{}) {
+            return impl().get_value_ptr_impl (discard);
+        }
+    //! @}
+
+    //! \name Object lifetime
+    //! @{
+    protected:
+        //! \brief
+        //!     Create and initialize
+        //! \param freq     The required hw timer's frequency
+        //! \param ticks    The required timer's reload value
+        timer_delay (size_t freq, Counter_t ticks) {
+            init (freq, ticks);
+        }
+        timer_delay() noexcept = default;                       //!< Default object is valid, but non-usable
+        timer_delay(const timer_delay&)             = delete;   //!< No copies
+        timer_delay& operator=(const timer_delay&)  = delete;   //!< No copies
+        //! \note
+        //! We are not initializing the timer via default ctor, in order to be able to
+        //! declare a timer_delay object globally and initialize it after the call to main().
+    //! @}
+
+    private:
+        //! Period to frequency compile time tool
+        constexpr Counter_t period2freq (double period) noexcept {
+            return (Counter_t)(1 / period);
+        }
+
+        /*!
+         * \brief   Return the systems best approximation for ticks per msec
+         * \return  The calculated value or zero if no calculation can apply
+         */
+        Counter_t ticks_per_msec () {
+            Counter_t tck = (Counter_t)(frequency / period2freq(0.001));
+            return (tck <= 1) ? 1 : tck;
+        }
+
+        /*!
+         * \brief   Return the systems best approximation for ticks per usec
+         * \return  The calculated value or zero if no calculation can apply
+         */
+        Counter_t ticks_per_usec () {
+            Counter_t tck = (Counter_t)(frequency / period2freq(0.000001));
+            return (tck <= 1) ? 1 : tck;
+        }
+
+        /*!
+         * \brief   Return the systems best approximation for ticks per usec
+         * \return  The calculated value or zero if no calculation can apply
+         */
+        Counter_t ticks_per_100nsec () {
+            Counter_t tck = (Counter_t)(frequency / period2freq(0.0000001));
+            return (tck <= 1) ? 1 : tck;
+        }
+
+    public:
+        /*!
+         * \brief
+         *      Initializes both object members and hw timer.
+         *
+         * \param freq      The required hw timer's frequency
+         * \param ticks     The required timer's reload value
+         * \return
+         */
+        bool init (size_t freq, Counter_t ticks) {
+            if (set_frequency(freq, ticks))
+                return false;
+            volatile Counter_t* v = get_value_ptr();
+
+            value     = (v != nullptr) ? v : value;
+            frequency = freq;
+            max_ticks = ticks;
+            tp1ms  = ticks_per_msec();
+            tp1us  = ticks_per_usec();
+            tp100ns= ticks_per_100nsec();
+            return true;
+        }
+
+        /*!
+         * \brief
+         *    A code based delay implementation, using hw timer for timing.
+         *    This is NOT accurate but it ensures that the time passed is always
+         *    more than the requested value.
+         *    The delay values are multiplications of 1 msec.
+         * \param   msec     Time in msec for delay
+         */
+        void delay_ms (int msec) {
+            marker_t m, m2, m1 = (marker_t)*value;
+
+            msec *= tp1ms;
+
+            // Eat the time difference from msec value.
+            do {
+                m2 = (marker_t)(*value);
+                m = m2 - m1;
+                msec -= (m>=0) ? m : max_ticks + m;
+                m1 = m2;
+            } while (msec>0);
+        }
+
+        /*!
+         * \brief
+         *    A code based delay implementation, using hw timer for timing.
+         *    This is NOT accurate but it ensures that the time passed is always
+         *    more than the requested value.
+         *    The delay values are multiplications of 1 usec.
+         * \param   usec     Time in usec for delay
+         */
+        void delay_us (int usec) {
+            marker_t m, m2, m1 = (marker_t)*value;
+
+            usec *= tp1us;
+            if ((marker_t)(*value) - m1 > usec) // Very small delays may return here.
+            return;
+
+            // Eat the time difference from usec value.
+            do {
+                m2 = (marker_t)(*value);
+                m = m2 - m1;
+                usec -= (m>=0) ? m : max_ticks + m;
+                m1 = m2;
+            } while (usec>0);
+        }
+
+        /*!
+         * \brief
+         *    A code based delay implementation, using hw timer for timing.
+         *    This is NOT accurate but it ensures that the time passed is always
+         *    more than the requested value.
+         *    The delay values are multiplications of 100 nsec.
+         * \param   _100nsec     Time in 100nsec for delay
+         */
+        void delay_100ns (int _100nsec) {
+            marker_t m, m2, m1 = (marker_t)*value;
+
+            _100nsec *= tp100ns;
+            if ((marker_t)(*value) - m1 > _100nsec) // Very small delays may return here.
+                return;
+
+            // Eat the time difference from _100nsec value.
+            do {
+                m2 = (marker_t)(*value);
+                m = m2 - m1;
+                _100nsec -= (m>=0) ? m : max_ticks + m;
+                m1 = m2;
+            } while (_100nsec>0);
+        }
+
+        /*!
+         * \brief
+         *    A code based polling version delay implementation, using hw timer for timing.
+         *    This is NOT accurate but it ensures that the time passed is always
+         *    more than the requested value.
+         *    The delay values are multiplications of 1 msec.
+         * \param   msec     Time in msec for delay
+         * \return  The status of ongoing delay
+         *    \arg  false:    Delay time has passed
+         *    \arg  true:     Delay is ongoing, keep calling
+         */
+        bool check_msec (int msec) {
+            static marker_t m1=-1, cnt;
+            marker_t m, m2;
+
+            if (m1 == -1) {
+                m1 = *value;
+                cnt = tp1ms * msec;
+            }
+
+            // Eat the time difference from msec value.
+            if (cnt>0) {
+                m2 = (marker_t)(*value);
+                m = m2-m1;
+                cnt -= (m>=0) ? m : max_ticks + m;
+                m1 = m2;
+                return 1;   // wait
+            } else {
+                m1 = -1;
+                return 0;   // do not wait any more
+            }
+        }
+
+        /*!
+         * \brief
+         *    A code based polling version delay implementation, using hw timer for timing.
+         *    This is NOT accurate but it ensures that the time passed is always
+         *    more than the requested value.
+         *    The delay values are multiplications of 1 usec.
+         * \param   usec     Time in usec for delay
+         * \return  The status of ongoing delay
+         *    \arg  false:    Delay time has passed
+         *    \arg  true:     Delay is ongoing, keep calling
+         */
+        bool check_usec (int usec) {
+            static marker_t m1=-1, cnt;
+            marker_t m, m2;
+
+            if (m1 == -1) {
+                m1 = *value;
+                cnt = tp1us * usec;
+            }
+
+            // Eat the time difference from usec value.
+            if (cnt>0) {
+                m2 = (marker_t)(*value);
+                m = m2-m1;
+                cnt -= (m>=0) ? m : max_ticks + m;
+                m1 = m2;
+                return 1;   // wait
+            } else {
+                m1 = -1;
+                return 0;   // do not wait any more
+            }
+        }
+
+
+        /*!
+         * \brief
+         *    A code based polling version delay implementation, using hw timer for timing.
+         *    This is NOT accurate but it ensures that the time passed is always
+         *    more than the requested value.
+         *    The delay values are multiplications of 100 nsec.
+         * \param
+         *    _100nsec     Time in 100nsec for delay
+         * \return  The status of ongoing delay
+         *    \arg  false:    Delay time has passed
+         *    \arg  true:     Delay is ongoing, keep calling
+         */
+        bool check_100nsec (int _100nsec) {
+            static marker_t m1=-1, cnt;
+            marker_t m, m2;
+
+            if (m1 == -1) {
+                m1 = *value;
+                cnt = tp100ns * _100nsec;
+            }
+
+            // Eat the time difference from _100nsec value.
+            if (cnt>0) {
+                m2 = (marker_t)(*value);
+                m = m2-m1;
+                cnt -= (m>=0) ? m : max_ticks + m;
+                m1 = m2;
+                return 1;   // wait
+            }
+            else {
+                m1 = -1;
+                return 0;   // do not wait any more
+            }
+        }
+
+    private:
+        static constexpr Counter_t zero = 0;    //!< A always zero place
+
+        value_t*    value {(value_t*)&zero};    //!< Pointer to hw timer's counter register
+                                                //!< We initialize it to &zero to avoid nullptr dereference
+        size_t      frequency{};                //!< The frequency of the timer
+        Counter_t   max_ticks{};                //!< The reload value of the timer
+        Counter_t   tp1ms{};                    //!< ticks per ms temporary variable
+        Counter_t   tp1us{};                    //!< ticks per us temporary variable
+        Counter_t   tp100ns{};                  //!< ticks per 100ns temporary variable
+    };
+
+
+} // namespace tbx
+
+#endif /* TBX_UTILS_TIMER_DELAY_H_ */

test/Makefile

@@ -188,7 +188,7 @@ $(BUILD_DIR)/$(TARGET): $(OBJ)
 	@mkdir -p $(@D)
 	@echo Linking to target: $(TARGET)
 	$(DOCKER) $(CXX) $(LDFLAGS) $(MAP_FLAG) -o $(@D)/$(TARGET) $(OBJ)
-	$(DOCKER) $(ODUMP) -h -S $(BUILD_DIR)/$(TARGET) > $(BUILD_DIR)/$(basename $(TARGET)).list
+#	$(DOCKER) $(ODUMP) -h -S $(BUILD_DIR)/$(TARGET) > $(BUILD_DIR)/$(basename $(TARGET)).list
 #	$(DOCKER) $(OCOPY) -O ihex $(BUILD_DIR)/$(TARGET) $(BUILD_DIR)/$(basename $(TARGET)).hex
 	@echo
 	@echo Print size information

test/tests/deque.cpp

@@ -34,6 +34,14 @@
 
 #include <array>
 #include <type_traits>
+#include <cstring>
+#ifndef WIN_TRHEADS
+#include <mutex>
+#include <thread>
+#else
+#include <mingw.thread.h>
+#include <mingw.mutex.h>
+#endif
 
 namespace Tdeque {
     using namespace tbx;
@@ -415,4 +423,47 @@ namespace Tdeque {
 
         EXPECT_EQ(9, check_it);         // run through all
     }
+
+    TEST(Tdeque, race) {
+        constexpr size_t N = 1000000;
+        deque<int, N, true> q;
+        int result[N];
+
+        auto push_front = [&](){
+            for (size_t i=1 ; i<=N ; ++i)   q.push_front(i);
+        };
+        auto push_back = [&](){
+            for (size_t i=1 ; i<=N ; ++i)   q.push_back(i);
+        };
+        auto pop_front = [&](){
+            for (size_t i=0 ; i<N ; ) {
+                result[i] = q.pop_front();
+                if (result[i] != int{})
+                    ++i;
+            }
+        };
+        auto pop_back = [&](){
+            for (size_t i=0 ; i<N ; ) {
+                result[i] = q.pop_back();
+                if (result[i] != int{})
+                    ++i;
+            }
+        };
+
+        std::memset(result, 0, sizeof result);
+        std::thread th1 (push_front);
+        std::thread th2 (pop_back);
+        th1.join();
+        th2.join();
+        for (size_t i=0 ; i<N ; ++i)
+            EXPECT_EQ (result[i], (int)i+1);
+
+        std::memset(result, 0, sizeof result);
+        std::thread th3 (push_back);
+        std::thread th4 (pop_front);
+        th3.join();
+        th4.join();
+        for (size_t i=0 ; i<N ; ++i)
+            EXPECT_EQ (result[i], (int)i+1);
+    }
 }