arm_q15_to_q7.c
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00001 /* ---------------------------------------------------------------------------- 00002 * Copyright (C) 2010 ARM Limited. All rights reserved. 00003 * 00004 * $Date: 15. July 2011 00005 * $Revision: V1.0.10 00006 * 00007 * Project: CMSIS DSP Library 00008 * Title: arm_q15_to_q7.c 00009 * 00010 * Description: Converts the elements of the Q15 vector to Q7 vector. 00011 * 00012 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 00013 * 00014 * Version 1.0.10 2011/7/15 00015 * Big Endian support added and Merged M0 and M3/M4 Source code. 00016 * 00017 * Version 1.0.3 2010/11/29 00018 * Re-organized the CMSIS folders and updated documentation. 00019 * 00020 * Version 1.0.2 2010/11/11 00021 * Documentation updated. 00022 * 00023 * Version 1.0.1 2010/10/05 00024 * Production release and review comments incorporated. 00025 * 00026 * Version 1.0.0 2010/09/20 00027 * Production release and review comments incorporated. 00028 * ---------------------------------------------------------------------------- */ 00029 00030 #include "arm_math.h" 00031 00060 void arm_q15_to_q7( 00061 q15_t * pSrc, 00062 q7_t * pDst, 00063 uint32_t blockSize) 00064 { 00065 q15_t *pIn = pSrc; /* Src pointer */ 00066 uint32_t blkCnt; /* loop counter */ 00067 00068 #ifndef ARM_MATH_CM0 00069 00070 /* Run the below code for Cortex-M4 and Cortex-M3 */ 00071 00072 /*loop Unrolling */ 00073 blkCnt = blockSize >> 2u; 00074 00075 /* First part of the processing with loop unrolling. Compute 4 outputs at a time. 00076 ** a second loop below computes the remaining 1 to 3 samples. */ 00077 while(blkCnt > 0u) 00078 { 00079 /* C = (q7_t) A >> 8 */ 00080 /* convert from q15 to q7 and then store the results in the destination buffer */ 00081 *pDst++ = (q7_t) (*pIn++ >> 8); 00082 *pDst++ = (q7_t) (*pIn++ >> 8); 00083 *pDst++ = (q7_t) (*pIn++ >> 8); 00084 *pDst++ = (q7_t) (*pIn++ >> 8); 00085 00086 /* Decrement the loop counter */ 00087 blkCnt--; 00088 } 00089 00090 /* If the blockSize is not a multiple of 4, compute any remaining output samples here. 00091 ** No loop unrolling is used. */ 00092 blkCnt = blockSize % 0x4u; 00093 00094 #else 00095 00096 /* Run the below code for Cortex-M0 */ 00097 00098 /* Loop over blockSize number of values */ 00099 blkCnt = blockSize; 00100 00101 #endif /* #ifndef ARM_MATH_CM0 */ 00102 00103 while(blkCnt > 0u) 00104 { 00105 /* C = (q7_t) A >> 8 */ 00106 /* convert from q15 to q7 and then store the results in the destination buffer */ 00107 *pDst++ = (q7_t) (*pIn++ >> 8); 00108 00109 /* Decrement the loop counter */ 00110 blkCnt--; 00111 } 00112 00113 } 00114
