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# arm_scale_q31.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_scale_q31.c
    00009 *
    00010 * Description:  Multiplies a Q31 vector by a scalar.
    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 * Version 0.0.7  2010/06/10
    00030 *    Misra-C changes done
    00031 * -------------------------------------------------------------------- */
    00032
    00033 #include "arm_math.h"
    00034
    00059 void arm_scale_q31(
    00060   q31_t * pSrc,
    00061   q31_t scaleFract,
    00062   int8_t shift,
    00063   q31_t * pDst,
    00064   uint32_t blockSize)
    00065 {
    00066   int8_t kShift = 31 - shift;                    /* Shift to apply after scaling */
    00067   uint32_t blkCnt;                               /* loop counter */
    00068
    00069 #ifndef ARM_MATH_CM0
    00070
    00071 /* Run the below code for Cortex-M4 and Cortex-M3 */
    00072
    00073   /*loop Unrolling */
    00074   blkCnt = blockSize >> 2u;
    00075
    00076   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
    00077    ** a second loop below computes the remaining 1 to 3 samples. */
    00078   while(blkCnt > 0u)
    00079   {
    00080     /* C = A * scale */
    00081     /* Scale the input and then store the results in the destination buffer. */
    00082     *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift);
    00083     *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift);
    00084     *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift);
    00085     *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift);
    00086
    00087     /* Decrement the loop counter */
    00088     blkCnt--;
    00089   }
    00090
    00091   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00092    ** No loop unrolling is used. */
    00093   blkCnt = blockSize % 0x4u;
    00094
    00095 #else
    00096
    00097   /* Run the below code for Cortex-M0 */
    00098
    00099   /* Initialize blkCnt with number of samples */
    00100   blkCnt = blockSize;
    00101
    00102 #endif /* #ifndef ARM_MATH_CM0 */
    00103
    00104   while(blkCnt > 0u)
    00105   {
    00106     /* C = A * scale */
    00107     /* Scale the input and then store the result in the destination buffer. */
    00108     *pDst++ = clip_q63_to_q31(((q63_t) * pSrc++ * scaleFract) >> kShift);
    00109
    00110     /* Decrement the loop counter */
    00111     blkCnt--;
    00112   }
    00113 }
    00114

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