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CMSIS DSP library

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cmsis_dsp/SupportFunctions/arm_q31_to_float.c@1:fdd22bb7aa52, 2012-11-28 (annotated)

Committer:
emilmont
Date:
Wed Nov 28 12:30:09 2012 +0000
Revision:
1:fdd22bb7aa52
Child:
2:da51fb522205
DSP library code

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 1:fdd22bb7aa52 5 * $Revision: V1.1.0
emilmont 1:fdd22bb7aa52 6 *
emilmont 1:fdd22bb7aa52 7 * Project: CMSIS DSP Library
emilmont 1:fdd22bb7aa52 8 * Title: arm_q31_to_float.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 1:fdd22bb7aa52 10 * Description: Converts the elements of the Q31 vector to floating-point 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 * @defgroup q31_to_x Convert 32-bit Integer value
emilmont 1:fdd22bb7aa52 41 */
emilmont 1:fdd22bb7aa52 42
emilmont 1:fdd22bb7aa52 43 /**
emilmont 1:fdd22bb7aa52 44 * @addtogroup q31_to_x
emilmont 1:fdd22bb7aa52 45 * @{
emilmont 1:fdd22bb7aa52 46 */
emilmont 1:fdd22bb7aa52 47
emilmont 1:fdd22bb7aa52 48 /**
emilmont 1:fdd22bb7aa52 49 * @brief Converts the elements of the Q31 vector to floating-point vector.
emilmont 1:fdd22bb7aa52 50 * @param[in] *pSrc points to the Q31 input vector
emilmont 1:fdd22bb7aa52 51 * @param[out] *pDst points to the floating-point output vector
emilmont 1:fdd22bb7aa52 52 * @param[in] blockSize length of the input vector
emilmont 1:fdd22bb7aa52 53 * @return none.
emilmont 1:fdd22bb7aa52 54 *
emilmont 1:fdd22bb7aa52 55 * \par Description:
emilmont 1:fdd22bb7aa52 56 *
emilmont 1:fdd22bb7aa52 57 * The equation used for the conversion process is:
emilmont 1:fdd22bb7aa52 58 *
emilmont 1:fdd22bb7aa52 59 * <pre>
emilmont 1:fdd22bb7aa52 60 * pDst[n] = (float32_t) pSrc[n] / 2147483648; 0 <= n < blockSize.
emilmont 1:fdd22bb7aa52 61 * </pre>
emilmont 1:fdd22bb7aa52 62 *
emilmont 1:fdd22bb7aa52 63 */
emilmont 1:fdd22bb7aa52 64
emilmont 1:fdd22bb7aa52 65
emilmont 1:fdd22bb7aa52 66 void arm_q31_to_float(
emilmont 1:fdd22bb7aa52 67 q31_t * pSrc,
emilmont 1:fdd22bb7aa52 68 float32_t * pDst,
emilmont 1:fdd22bb7aa52 69 uint32_t blockSize)
emilmont 1:fdd22bb7aa52 70 {
emilmont 1:fdd22bb7aa52 71 q31_t *pIn = pSrc; /* Src pointer */
emilmont 1:fdd22bb7aa52 72 uint32_t blkCnt; /* loop counter */
emilmont 1:fdd22bb7aa52 73
emilmont 1:fdd22bb7aa52 74
emilmont 1:fdd22bb7aa52 75 #ifndef ARM_MATH_CM0
emilmont 1:fdd22bb7aa52 76
emilmont 1:fdd22bb7aa52 77 /* Run the below code for Cortex-M4 and Cortex-M3 */
emilmont 1:fdd22bb7aa52 78
emilmont 1:fdd22bb7aa52 79 /*loop Unrolling */
emilmont 1:fdd22bb7aa52 80 blkCnt = blockSize >> 2u;
emilmont 1:fdd22bb7aa52 81
emilmont 1:fdd22bb7aa52 82 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
emilmont 1:fdd22bb7aa52 83 ** a second loop below computes the remaining 1 to 3 samples. */
emilmont 1:fdd22bb7aa52 84 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 85 {
emilmont 1:fdd22bb7aa52 86 /* C = (float32_t) A / 2147483648 */
emilmont 1:fdd22bb7aa52 87 /* convert from q31 to float and then store the results in the destination buffer */
emilmont 1:fdd22bb7aa52 88 *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
emilmont 1:fdd22bb7aa52 89 *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
emilmont 1:fdd22bb7aa52 90 *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
emilmont 1:fdd22bb7aa52 91 *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
emilmont 1:fdd22bb7aa52 92
emilmont 1:fdd22bb7aa52 93 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 94 blkCnt--;
emilmont 1:fdd22bb7aa52 95 }
emilmont 1:fdd22bb7aa52 96
emilmont 1:fdd22bb7aa52 97 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
emilmont 1:fdd22bb7aa52 98 ** No loop unrolling is used. */
emilmont 1:fdd22bb7aa52 99 blkCnt = blockSize % 0x4u;
emilmont 1:fdd22bb7aa52 100
emilmont 1:fdd22bb7aa52 101 #else
emilmont 1:fdd22bb7aa52 102
emilmont 1:fdd22bb7aa52 103 /* Run the below code for Cortex-M0 */
emilmont 1:fdd22bb7aa52 104
emilmont 1:fdd22bb7aa52 105 /* Loop over blockSize number of values */
emilmont 1:fdd22bb7aa52 106 blkCnt = blockSize;
emilmont 1:fdd22bb7aa52 107
emilmont 1:fdd22bb7aa52 108 #endif /* #ifndef ARM_MATH_CM0 */
emilmont 1:fdd22bb7aa52 109
emilmont 1:fdd22bb7aa52 110 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 111 {
emilmont 1:fdd22bb7aa52 112 /* C = (float32_t) A / 2147483648 */
emilmont 1:fdd22bb7aa52 113 /* convert from q31 to float and then store the results in the destination buffer */
emilmont 1:fdd22bb7aa52 114 *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
emilmont 1:fdd22bb7aa52 115
emilmont 1:fdd22bb7aa52 116 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 117 blkCnt--;
emilmont 1:fdd22bb7aa52 118 }
emilmont 1:fdd22bb7aa52 119 }
emilmont 1:fdd22bb7aa52 120
emilmont 1:fdd22bb7aa52 121 /**
emilmont 1:fdd22bb7aa52 122 * @} end of q31_to_x group
emilmont 1:fdd22bb7aa52 123 */