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A bundled STM32F10x Std Periph and CMSIS library
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STM32F10x_Std_Lib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_biquad_cascade_df2T_ini...

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  1. /*-----------------------------------------------------------------------------    

  2. * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    

  3. *    

  4. * $Date:        12. March 2014

  5. * $Revision: 	V1.4.4

  6. *    

  7. * Project: 	    CMSIS DSP Library    

  8. * Title:        arm_biquad_cascade_df2T_init_f32.c    

  9. *    

  10. * Description:  Initialization function for the floating-point transposed   

  11. *               direct form II Biquad cascade filter.   

  12. *    

  13. * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0

  14. *  

  15. * Redistribution and use in source and binary forms, with or without 

  16. * modification, are permitted provided that the following conditions

  17. * are met:

  18. *   - Redistributions of source code must retain the above copyright

  19. *     notice, this list of conditions and the following disclaimer.

  20. *   - Redistributions in binary form must reproduce the above copyright

  21. *     notice, this list of conditions and the following disclaimer in

  22. *     the documentation and/or other materials provided with the 

  23. *     distribution.

  24. *   - Neither the name of ARM LIMITED nor the names of its contributors

  25. *     may be used to endorse or promote products derived from this

  26. *     software without specific prior written permission.

  27. *

  28. * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

  29. * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

  30. * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

  31. * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 

  32. * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,

  33. * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,

  34. * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

  35. * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

  36. * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

  37. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

  38. * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

  39. * POSSIBILITY OF SUCH DAMAGE.   

  40. * ---------------------------------------------------------------------------*/

  41. 

  42. #include "arm_math.h"

  43. 

  44. /**    

  45.  * @ingroup groupFilters    

  46.  */

  47. 

  48. /**    

  49.  * @addtogroup BiquadCascadeDF2T    

  50.  * @{    

  51.  */

  52. 

  53. /**   

  54.  * @brief  Initialization function for the floating-point transposed direct form II Biquad cascade filter.   

  55.  * @param[in,out] *S           points to an instance of the filter data structure.   

  56.  * @param[in]     numStages    number of 2nd order stages in the filter.   

  57.  * @param[in]     *pCoeffs     points to the filter coefficients.   

  58.  * @param[in]     *pState      points to the state buffer.   

  59.  * @return        none   

  60.  *    

  61.  * <b>Coefficient and State Ordering:</b>    

  62.  * \par    

  63.  * The coefficients are stored in the array <code>pCoeffs</code> in the following order:    

  64.  * <pre>    

  65.  *     {b10, b11, b12, a11, a12, b20, b21, b22, a21, a22, ...}    

  66.  * </pre>    

  67.  *    

  68.  * \par    

  69.  * where <code>b1x</code> and <code>a1x</code> are the coefficients for the first stage,    

  70.  * <code>b2x</code> and <code>a2x</code> are the coefficients for the second stage,    

  71.  * and so on.  The <code>pCoeffs</code> array contains a total of <code>5*numStages</code> values.    

  72.  *    

  73.  * \par    

  74.  * The <code>pState</code> is a pointer to state array.    

  75.  * Each Biquad stage has 2 state variables <code>d1,</code> and <code>d2</code>.    

  76.  * The 2 state variables for stage 1 are first, then the 2 state variables for stage 2, and so on.    

  77.  * The state array has a total length of <code>2*numStages</code> values.    

  78.  * The state variables are updated after each block of data is processed; the coefficients are untouched.    

  79.  */

  80. 

  81. void arm_biquad_cascade_df2T_init_f32(

  82.   arm_biquad_cascade_df2T_instance_f32 * S,

  83.   uint8_t numStages,

  84.   float32_t * pCoeffs,

  85.   float32_t * pState)

  86. {

  87.   /* Assign filter stages */

  88.   S->numStages = numStages;

  89. 

  90.   /* Assign coefficient pointer */

  91.   S->pCoeffs = pCoeffs;

  92. 

  93.   /* Clear state buffer and size is always 2 * numStages */

  94.   memset(pState, 0, (2u * (uint32_t) numStages) * sizeof(float32_t));

  95. 

  96.   /* Assign state pointer */

  97.   S->pState = pState;

  98. }

  99. 

  100. /**    

  101.  * @} end of BiquadCascadeDF2T group    

  102.  */