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arm_scale_f32.c
00001 /* ---------------------------------------------------------------------- 00002 * Copyright (C) 2010 ARM Limited. All rights reserved. 00003 * 00004 * $Date: 29. November 2010 00005 * $Revision: V1.0.3 00006 * 00007 * Project: CMSIS DSP Library 00008 * Title: arm_scale_f32.c 00009 * 00010 * Description: Multiplies a floating-point vector by a scalar. 00011 * 00012 * Target Processor: Cortex-M4/Cortex-M3 00013 * 00014 * Version 1.0.3 2010/11/29 00015 * Re-organized the CMSIS folders and updated documentation. 00016 * 00017 * Version 1.0.2 2010/11/11 00018 * Documentation updated. 00019 * 00020 * Version 1.0.1 2010/10/05 00021 * Production release and review comments incorporated. 00022 * 00023 * Version 1.0.0 2010/09/20 00024 * Production release and review comments incorporated 00025 * 00026 * Version 0.0.7 2010/06/10 00027 * Misra-C changes done 00028 * ---------------------------------------------------------------------------- */ 00029 00030 #include "arm_math.h" 00031 00032 /** 00033 * @ingroup groupMath 00034 */ 00035 00036 /** 00037 * @defgroup scale Vector Scale 00038 * 00039 * Multiply a vector by a scalar value. For floating-point data, the algorithm used is: 00040 * 00041 * <pre> 00042 * pDst[n] = pSrc[n] * scale, 0 <= n < blockSize. 00043 * </pre> 00044 * 00045 * In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is represented by 00046 * a fractional multiplication <code>scaleFract</code> and an arithmetic shift <code>shift</code>. 00047 * The shift allows the gain of the scaling operation to exceed 1.0. 00048 * The algorithm used with fixed-point data is: 00049 * 00050 * <pre> 00051 * pDst[n] = (pSrc[n] * scaleFract) << shift, 0 <= n < blockSize. 00052 * </pre> 00053 * 00054 * The overall scale factor applied to the fixed-point data is 00055 * <pre> 00056 * scale = scaleFract * 2^shift. 00057 * </pre> 00058 */ 00059 00060 /** 00061 * @addtogroup scale 00062 * @{ 00063 */ 00064 00065 /** 00066 * @brief Multiplies a floating-point vector by a scalar. 00067 * @param[in] *pSrc points to the input vector 00068 * @param[in] scale scale factor to be applied 00069 * @param[out] *pDst points to the output vector 00070 * @param[in] blockSize number of samples in the vector 00071 * @return none. 00072 */ 00073 00074 00075 void arm_scale_f32( 00076 float32_t * pSrc, 00077 float32_t scale, 00078 float32_t * pDst, 00079 uint32_t blockSize) 00080 { 00081 uint32_t blkCnt; /* loop counter */ 00082 00083 /*loop Unrolling */ 00084 blkCnt = blockSize >> 2u; 00085 00086 /* First part of the processing with loop unrolling. Compute 4 outputs at a time. 00087 ** a second loop below computes the remaining 1 to 3 samples. */ 00088 while(blkCnt > 0u) 00089 { 00090 /* C = A * scale */ 00091 /* Scale the input and then store the results in the destination buffer. */ 00092 *pDst++ = (*pSrc++) * scale; 00093 *pDst++ = (*pSrc++) * scale; 00094 *pDst++ = (*pSrc++) * scale; 00095 *pDst++ = (*pSrc++) * scale; 00096 00097 /* Decrement the loop counter */ 00098 blkCnt--; 00099 } 00100 00101 /* If the blockSize is not a multiple of 4, compute any remaining output samples here. 00102 ** No loop unrolling is used. */ 00103 blkCnt = blockSize % 0x4u; 00104 00105 while(blkCnt > 0u) 00106 { 00107 /* C = A * scale */ 00108 /* Scale the input and then store the result in the destination buffer. */ 00109 *pDst++ = (*pSrc++) * scale; 00110 00111 /* Decrement the loop counter */ 00112 blkCnt--; 00113 } 00114 } 00115 00116 /** 00117 * @} end of scale group 00118 */
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