CMSIS DSP Library from CMSIS 2.0. See http://www.onarm.com/cmsis/ for full details
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arm_sub_q31.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_sub_q31.c 00009 * 00010 * Description: Q31 vector subtraction. 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 * @addtogroup BasicSub 00038 * @{ 00039 */ 00040 00041 /** 00042 * @brief Q31 vector subtraction. 00043 * @param[in] *pSrcA points to the first input vector 00044 * @param[in] *pSrcB points to the second input vector 00045 * @param[out] *pDst points to the output vector 00046 * @param[in] blockSize number of samples in each vector 00047 * @return none. 00048 * 00049 * <b>Scaling and Overflow Behavior:</b> 00050 * \par 00051 * The function uses saturating arithmetic. 00052 * Results outside of the allowable Q31 range [0x80000000 0x7FFFFFFF] will be saturated. 00053 */ 00054 00055 void arm_sub_q31( 00056 q31_t * pSrcA, 00057 q31_t * pSrcB, 00058 q31_t * pDst, 00059 uint32_t blockSize) 00060 { 00061 uint32_t blkCnt; /* loop counter */ 00062 00063 00064 /*loop Unrolling */ 00065 blkCnt = blockSize >> 2u; 00066 00067 /* First part of the processing with loop unrolling. Compute 4 outputs at a time. 00068 ** a second loop below computes the remaining 1 to 3 samples. */ 00069 while(blkCnt > 0u) 00070 { 00071 /* C = A - B */ 00072 /* Subtract and then store the results in the destination buffer. */ 00073 *pDst++ = __QSUB(*pSrcA++, *pSrcB++); 00074 *pDst++ = __QSUB(*pSrcA++, *pSrcB++); 00075 *pDst++ = __QSUB(*pSrcA++, *pSrcB++); 00076 *pDst++ = __QSUB(*pSrcA++, *pSrcB++); 00077 00078 /* Decrement the loop counter */ 00079 blkCnt--; 00080 } 00081 00082 /* If the blockSize is not a multiple of 4, compute any remaining output samples here. 00083 ** No loop unrolling is used. */ 00084 blkCnt = blockSize % 0x4u; 00085 00086 while(blkCnt > 0u) 00087 { 00088 /* C = A - B */ 00089 /* Subtract and then store the result in the destination buffer. */ 00090 *pDst++ = __QSUB(*pSrcA++, *pSrcB++); 00091 00092 /* Decrement the loop counter */ 00093 blkCnt--; 00094 } 00095 } 00096 00097 /** 00098 * @} end of BasicSub group 00099 */
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