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CMSIS DSP library

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cmsis_dsp/SupportFunctions/arm_q31_to_q7.c@2:da51fb522205, 2013-05-30 (annotated)

Committer:
emilmont
Date:
Thu May 30 17:10:11 2013 +0100
Revision:
2:da51fb522205
Parent:
1:fdd22bb7aa52
Child:
3:7a284390b0ce
Keep "cmsis-dsp" module in synch with its source

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 1:fdd22bb7aa52 1 /* ----------------------------------------------------------------------------
emilmont 1:fdd22bb7aa52 2 * Copyright (C) 2010 ARM Limited. All rights reserved.
emilmont 1:fdd22bb7aa52 3 *
emilmont 1:fdd22bb7aa52 4 * $Date: 15. February 2012
emilmont 2:da51fb522205 5 * $Revision: V1.1.0
emilmont 1:fdd22bb7aa52 6 *
emilmont 2:da51fb522205 7 * Project: CMSIS DSP Library
emilmont 2:da51fb522205 8 * Title: arm_q31_to_q7.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 2:da51fb522205 10 * Description: Converts the elements of the Q31 vector to Q7 vector.
emilmont 1:fdd22bb7aa52 11 *
emilmont 1:fdd22bb7aa52 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emilmont 1:fdd22bb7aa52 13 *
emilmont 1:fdd22bb7aa52 14 * Version 1.1.0 2012/02/15
emilmont 1:fdd22bb7aa52 15 * Updated with more optimizations, bug fixes and minor API changes.
emilmont 1:fdd22bb7aa52 16 *
emilmont 1:fdd22bb7aa52 17 * Version 1.0.10 2011/7/15
emilmont 1:fdd22bb7aa52 18 * Big Endian support added and Merged M0 and M3/M4 Source code.
emilmont 1:fdd22bb7aa52 19 *
emilmont 1:fdd22bb7aa52 20 * Version 1.0.3 2010/11/29
emilmont 1:fdd22bb7aa52 21 * Re-organized the CMSIS folders and updated documentation.
emilmont 1:fdd22bb7aa52 22 *
emilmont 1:fdd22bb7aa52 23 * Version 1.0.2 2010/11/11
emilmont 1:fdd22bb7aa52 24 * Documentation updated.
emilmont 1:fdd22bb7aa52 25 *
emilmont 1:fdd22bb7aa52 26 * Version 1.0.1 2010/10/05
emilmont 1:fdd22bb7aa52 27 * Production release and review comments incorporated.
emilmont 1:fdd22bb7aa52 28 *
emilmont 1:fdd22bb7aa52 29 * Version 1.0.0 2010/09/20
emilmont 1:fdd22bb7aa52 30 * Production release and review comments incorporated.
emilmont 1:fdd22bb7aa52 31 * ---------------------------------------------------------------------------- */
emilmont 1:fdd22bb7aa52 32
emilmont 1:fdd22bb7aa52 33 #include "arm_math.h"
emilmont 1:fdd22bb7aa52 34
emilmont 1:fdd22bb7aa52 35 /**
emilmont 1:fdd22bb7aa52 36 * @ingroup groupSupport
emilmont 1:fdd22bb7aa52 37 */
emilmont 1:fdd22bb7aa52 38
emilmont 1:fdd22bb7aa52 39 /**
emilmont 1:fdd22bb7aa52 40 * @addtogroup q31_to_x
emilmont 1:fdd22bb7aa52 41 * @{
emilmont 1:fdd22bb7aa52 42 */
emilmont 1:fdd22bb7aa52 43
emilmont 1:fdd22bb7aa52 44 /**
emilmont 1:fdd22bb7aa52 45 * @brief Converts the elements of the Q31 vector to Q7 vector.
emilmont 1:fdd22bb7aa52 46 * @param[in] *pSrc points to the Q31 input vector
emilmont 1:fdd22bb7aa52 47 * @param[out] *pDst points to the Q7 output vector
emilmont 1:fdd22bb7aa52 48 * @param[in] blockSize length of the input vector
emilmont 1:fdd22bb7aa52 49 * @return none.
emilmont 1:fdd22bb7aa52 50 *
emilmont 1:fdd22bb7aa52 51 * \par Description:
emilmont 1:fdd22bb7aa52 52 *
emilmont 1:fdd22bb7aa52 53 * The equation used for the conversion process is:
emilmont 1:fdd22bb7aa52 54 *
emilmont 1:fdd22bb7aa52 55 * <pre>
emilmont 2:da51fb522205 56 * pDst[n] = (q7_t) pSrc[n] >> 24; 0 <= n < blockSize.
emilmont 1:fdd22bb7aa52 57 * </pre>
emilmont 1:fdd22bb7aa52 58 *
emilmont 1:fdd22bb7aa52 59 */
emilmont 1:fdd22bb7aa52 60
emilmont 1:fdd22bb7aa52 61
emilmont 1:fdd22bb7aa52 62 void arm_q31_to_q7(
emilmont 1:fdd22bb7aa52 63 q31_t * pSrc,
emilmont 1:fdd22bb7aa52 64 q7_t * pDst,
emilmont 1:fdd22bb7aa52 65 uint32_t blockSize)
emilmont 1:fdd22bb7aa52 66 {
emilmont 1:fdd22bb7aa52 67 q31_t *pIn = pSrc; /* Src pointer */
emilmont 1:fdd22bb7aa52 68 uint32_t blkCnt; /* loop counter */
emilmont 1:fdd22bb7aa52 69
emilmont 1:fdd22bb7aa52 70 #ifndef ARM_MATH_CM0
emilmont 1:fdd22bb7aa52 71
emilmont 1:fdd22bb7aa52 72 /* Run the below code for Cortex-M4 and Cortex-M3 */
emilmont 1:fdd22bb7aa52 73 q31_t in1, in2, in3, in4;
emilmont 1:fdd22bb7aa52 74 q7_t out1, out2, out3, out4;
emilmont 1:fdd22bb7aa52 75
emilmont 1:fdd22bb7aa52 76 /*loop Unrolling */
emilmont 1:fdd22bb7aa52 77 blkCnt = blockSize >> 2u;
emilmont 1:fdd22bb7aa52 78
emilmont 1:fdd22bb7aa52 79 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
emilmont 1:fdd22bb7aa52 80 ** a second loop below computes the remaining 1 to 3 samples. */
emilmont 1:fdd22bb7aa52 81 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 82 {
emilmont 1:fdd22bb7aa52 83 /* C = (q7_t) A >> 24 */
emilmont 1:fdd22bb7aa52 84 /* convert from q31 to q7 and then store the results in the destination buffer */
emilmont 1:fdd22bb7aa52 85 in1 = *pIn++;
emilmont 1:fdd22bb7aa52 86 in2 = *pIn++;
emilmont 1:fdd22bb7aa52 87 in3 = *pIn++;
emilmont 1:fdd22bb7aa52 88 in4 = *pIn++;
emilmont 1:fdd22bb7aa52 89
emilmont 1:fdd22bb7aa52 90 out1 = (q7_t) (in1 >> 24);
emilmont 1:fdd22bb7aa52 91 out2 = (q7_t) (in2 >> 24);
emilmont 1:fdd22bb7aa52 92 out3 = (q7_t) (in3 >> 24);
emilmont 1:fdd22bb7aa52 93 out4 = (q7_t) (in4 >> 24);
emilmont 1:fdd22bb7aa52 94
emilmont 1:fdd22bb7aa52 95 *__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4);
emilmont 1:fdd22bb7aa52 96
emilmont 1:fdd22bb7aa52 97 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 98 blkCnt--;
emilmont 1:fdd22bb7aa52 99 }
emilmont 1:fdd22bb7aa52 100
emilmont 1:fdd22bb7aa52 101 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
emilmont 1:fdd22bb7aa52 102 ** No loop unrolling is used. */
emilmont 1:fdd22bb7aa52 103 blkCnt = blockSize % 0x4u;
emilmont 1:fdd22bb7aa52 104
emilmont 1:fdd22bb7aa52 105 #else
emilmont 1:fdd22bb7aa52 106
emilmont 1:fdd22bb7aa52 107 /* Run the below code for Cortex-M0 */
emilmont 1:fdd22bb7aa52 108
emilmont 1:fdd22bb7aa52 109 /* Loop over blockSize number of values */
emilmont 1:fdd22bb7aa52 110 blkCnt = blockSize;
emilmont 1:fdd22bb7aa52 111
emilmont 1:fdd22bb7aa52 112 #endif /* #ifndef ARM_MATH_CM0 */
emilmont 1:fdd22bb7aa52 113
emilmont 1:fdd22bb7aa52 114 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 115 {
emilmont 1:fdd22bb7aa52 116 /* C = (q7_t) A >> 24 */
emilmont 1:fdd22bb7aa52 117 /* convert from q31 to q7 and then store the results in the destination buffer */
emilmont 1:fdd22bb7aa52 118 *pDst++ = (q7_t) (*pIn++ >> 24);
emilmont 1:fdd22bb7aa52 119
emilmont 1:fdd22bb7aa52 120 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 121 blkCnt--;
emilmont 1:fdd22bb7aa52 122 }
emilmont 1:fdd22bb7aa52 123
emilmont 1:fdd22bb7aa52 124 }
emilmont 1:fdd22bb7aa52 125
emilmont 1:fdd22bb7aa52 126 /**
emilmont 1:fdd22bb7aa52 127 * @} end of q31_to_x group
emilmont 1:fdd22bb7aa52 128 */