arm_q31_to_q7.c
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00001 /* ---------------------------------------------------------------------------- 00002 * Copyright (C) 2011 ARM Limited. All rights reserved. 00003 * 00004 * $Date: 15. December 2011 00005 * $Revision: V2.0.0 00006 * 00007 * Project: Cortex-R DSP Library 00008 * Title: arm_q31_to_q7.c 00009 * 00010 * Description: Converts the elements of the Q31 vector to Q7 vector. 00011 * 00012 * Target Processor: Cortex-R4/R5 00013 * 00014 * Version 1.0.0 2011/03/08 00015 * Alpha release. 00016 * 00017 * Version 1.0.1 2011/09/30 00018 * Beta release. 00019 * 00020 * Version 2.0.0 2011/12/15 00021 * Final release. 00022 * 00023 * ---------------------------------------------------------------------------- */ 00024 #include "arm_math.h" 00025 00057 void arm_q31_to_q7( 00058 q31_t * pSrc, 00059 q7_t * pDst, 00060 uint32_t blockSize) 00061 { 00062 q31_t *pIn = pSrc; /* Src pointer */ 00063 uint32_t blkCnt; /* loop counter */ 00064 q31_t in1, in2, in3, in4; 00065 q31_t in5, in6, in7, in8; 00066 q7_t out1, out2, out3, out4; 00067 00068 /*loop Unrolling */ 00069 blkCnt = blockSize >> 3u; 00070 00071 /* First part of the processing with loop unrolling. Compute 8 outputs at a time. 00072 ** a second loop below computes the remaining 1 to 7 samples. */ 00073 while(blkCnt > 0u) 00074 { 00075 /* C = (q7_t) A >> 24 */ 00076 /* convert from q31 to q7 and then store the results in the destination buffer */ 00077 /* read input samples */ 00078 in1 = pIn[0]; 00079 in2 = pIn[1]; 00080 out1 = (q7_t)(in1 >> 24); 00081 in3 = pIn[2]; 00082 out2 = (q7_t)(in2 >> 24); 00083 in4 = pIn[3]; 00084 00085 out3 = (q7_t)(in3 >> 24); 00086 out4 = (q7_t)(in4 >> 24); 00087 00088 *__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4); 00089 00090 in5 = pIn[4]; 00091 in6 = pIn[5]; 00092 out1 = (q7_t)(in5 >> 24); 00093 in7 = pIn[6]; 00094 out2 = (q7_t)(in6 >> 24); 00095 in8 = pIn[7]; 00096 00097 out3 = (q7_t)(in7 >> 24); 00098 out4 = (q7_t)(in8 >> 24); 00099 00100 *__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4); 00101 00102 /* update pointer to process next samples */ 00103 pIn += 8u; 00104 00105 /* Decrement the loop counter */ 00106 blkCnt--; 00107 } 00108 00109 /* If the blockSize is not a multiple of 8, compute any remaining output samples here. 00110 ** No loop unrolling is used. */ 00111 blkCnt = blockSize % 0x8u; 00112 00113 while(blkCnt > 0u) 00114 { 00115 /* C = (q7_t) A >> 24 */ 00116 /* convert from q31 to q7 and then store the results in the destination buffer */ 00117 *pDst++ = (q7_t) (*pIn++ >> 24); 00118 00119 /* Decrement the loop counter */ 00120 blkCnt--; 00121 } 00122 00123 } 00124
