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# arm_q31_to_float.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_q31_to_float.c
    00009 *
    00010 * Description:  Converts the elements of the Q31 vector to floating-point 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
    00063 void arm_q31_to_float(
    00064   q31_t * pSrc,
    00065   float32_t * pDst,
    00066   uint32_t blockSize)
    00067 {
    00068   q31_t *pIn = pSrc;                             /* Src pointer */
    00069   uint32_t blkCnt;                               /* loop counter */
    00070
    00071
    00072 #ifndef ARM_MATH_CM0
    00073
    00074   /* Run the below code for Cortex-M4 and Cortex-M3 */
    00075
    00076   /*loop Unrolling */
    00077   blkCnt = blockSize >> 2u;
    00078
    00079   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00080    ** a second loop below computes the remaining 1 to 3 samples. */
    00081   while(blkCnt > 0u)
    00082   {
    00083     /* C = (float32_t) A / 2147483648 */
    00084     /* convert from q31 to float and then store the results in the destination buffer */
    00085     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
    00086     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
    00087     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
    00088     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
    00089
    00090     /* Decrement the loop counter */
    00091     blkCnt--;
    00092   }
    00093
    00094   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00095    ** No loop unrolling is used. */
    00096   blkCnt = blockSize % 0x4u;
    00097
    00098 #else
    00099
    00100   /* Run the below code for Cortex-M0 */
    00101
    00102   /* Loop over blockSize number of values */
    00103   blkCnt = blockSize;
    00104
    00105 #endif /* #ifndef ARM_MATH_CM0 */
    00106
    00107   while(blkCnt > 0u)
    00108   {
    00109     /* C = (float32_t) A / 2147483648 */
    00110     /* convert from q31 to float and then store the results in the destination buffer */
    00111     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
    00112
    00113     /* Decrement the loop counter */
    00114     blkCnt--;
    00115   }
    00116 }
    00117

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