/* ---------------------------------------------------------------------- * Copyright (C) 2010-2014 ARM Limited. All rights reserved. * * $Date: 12. March 2014 * $Revision: V1.4.4 * * Project: CMSIS DSP Library * Title: arm_scale_f32.c * * Description: Multiplies a floating-point vector by a scalar. * * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * - Neither the name of ARM LIMITED nor the names of its contributors * may be used to endorse or promote products derived from this * software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * ---------------------------------------------------------------------------- */ #include "arm_math.h" /** * @ingroup groupMath */ /** * @defgroup scale Vector Scale * * Multiply a vector by a scalar value. For floating-point data, the algorithm used is: * *
        
 *     pDst[n] = pSrc[n] * scale,   0 <= n < blockSize.        
 * 
* * In the fixed-point Q7, Q15, and Q31 functions, scale is represented by * a fractional multiplication scaleFract and an arithmetic shift shift. * The shift allows the gain of the scaling operation to exceed 1.0. * The algorithm used with fixed-point data is: * *
        
 *     pDst[n] = (pSrc[n] * scaleFract) << shift,   0 <= n < blockSize.        
 * 
* * The overall scale factor applied to the fixed-point data is *
        
 *     scale = scaleFract * 2^shift.        
 * 
* * The functions support in-place computation allowing the source and destination * pointers to reference the same memory buffer. */ /** * @addtogroup scale * @{ */ /** * @brief Multiplies a floating-point vector by a scalar. * @param[in] *pSrc points to the input vector * @param[in] scale scale factor to be applied * @param[out] *pDst points to the output vector * @param[in] blockSize number of samples in the vector * @return none. */ void arm_scale_f32( float32_t * pSrc, float32_t scale, float32_t * pDst, uint32_t blockSize) { uint32_t blkCnt; /* loop counter */ #ifndef ARM_MATH_CM0_FAMILY /* Run the below code for Cortex-M4 and Cortex-M3 */ float32_t in1, in2, in3, in4; /* temporary variabels */ /*loop Unrolling */ blkCnt = blockSize >> 2u; /* First part of the processing with loop unrolling. Compute 4 outputs at a time. ** a second loop below computes the remaining 1 to 3 samples. */ while(blkCnt > 0u) { /* C = A * scale */ /* Scale the input and then store the results in the destination buffer. */ /* read input samples from source */ in1 = *pSrc; in2 = *(pSrc + 1); /* multiply with scaling factor */ in1 = in1 * scale; /* read input sample from source */ in3 = *(pSrc + 2); /* multiply with scaling factor */ in2 = in2 * scale; /* read input sample from source */ in4 = *(pSrc + 3); /* multiply with scaling factor */ in3 = in3 * scale; in4 = in4 * scale; /* store the result to destination */ *pDst = in1; *(pDst + 1) = in2; *(pDst + 2) = in3; *(pDst + 3) = in4; /* update pointers to process next samples */ pSrc += 4u; pDst += 4u; /* Decrement the loop counter */ blkCnt--; } /* If the blockSize is not a multiple of 4, compute any remaining output samples here. ** No loop unrolling is used. */ blkCnt = blockSize % 0x4u; #else /* Run the below code for Cortex-M0 */ /* Initialize blkCnt with number of samples */ blkCnt = blockSize; #endif /* #ifndef ARM_MATH_CM0_FAMILY */ while(blkCnt > 0u) { /* C = A * scale */ /* Scale the input and then store the result in the destination buffer. */ *pDst++ = (*pSrc++) * scale; /* Decrement the loop counter */ blkCnt--; } } /** * @} end of scale group */