CMSIS DSP Software Library: arm_scale_q7.c Source File

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# arm_scale_q7.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_q7.c
    00009 *
    00010 * Description:  Multiplies a Q7 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_q7(
    00060   q7_t * pSrc,
    00061   q7_t scaleFract,
    00062   int8_t shift,
    00063   q7_t * pDst,
    00064   uint32_t blockSize)
    00065 {
    00066   int8_t kShift = 7 - 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   q7_t in1, in2, in3, in4, out1, out2, out3, out4;      /* Temporary variables to store input & output */
    00073
    00074
    00075   /*loop Unrolling */
    00076   blkCnt = blockSize >> 2u;
    00077
    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     /* Reading 4 inputs from memory */
    00084     in1 = *pSrc++;
    00085     in2 = *pSrc++;
    00086     in3 = *pSrc++;
    00087     in4 = *pSrc++;
    00088
    00089     /* C = A * scale */
    00090     /* Scale the inputs and then store the results in the temporary variables. */
    00091     out1 = (q7_t) (__SSAT(((in1) * scaleFract) >> kShift, 8));
    00092     out2 = (q7_t) (__SSAT(((in2) * scaleFract) >> kShift, 8));
    00093     out3 = (q7_t) (__SSAT(((in3) * scaleFract) >> kShift, 8));
    00094     out4 = (q7_t) (__SSAT(((in4) * scaleFract) >> kShift, 8));
    00095
    00096     /* Packing the individual outputs into 32bit and storing in
    00097      * destination buffer in single write */
    00098     *__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4);
    00099
    00100     /* Decrement the loop counter */
    00101     blkCnt--;
    00102   }
    00103
    00104   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
    00105    ** No loop unrolling is used. */
    00106   blkCnt = blockSize % 0x4u;
    00107
    00108   while(blkCnt > 0u)
    00109   {
    00110     /* C = A * scale */
    00111     /* Scale the input and then store the result in the destination buffer. */
    00112     *pDst++ = (q7_t) (__SSAT(((*pSrc++) * scaleFract) >> kShift, 8));
    00113
    00114     /* Decrement the loop counter */
    00115     blkCnt--;
    00116   }
    00117
    00118 #else
    00119
    00120   /* Run the below code for Cortex-M0 */
    00121
    00122   /* Initialize blkCnt with number of samples */
    00123   blkCnt = blockSize;
    00124
    00125   while(blkCnt > 0u)
    00126   {
    00127     /* C = A * scale */
    00128     /* Scale the input and then store the result in the destination buffer. */
    00129     *pDst++ = (q7_t) (__SSAT((((q15_t) * pSrc++ * scaleFract) >> kShift), 8));
    00130
    00131     /* Decrement the loop counter */
    00132     blkCnt--;
    00133   }
    00134
    00135 #endif /* #ifndef ARM_MATH_CM0 */
    00136
    00137 }
    00138

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