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# arm_max_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_max_q31.c
    00009 *
    00010 * Description:  Maximum value of a Q31 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
    00051 void arm_max_q31(
    00052   q31_t * pSrc,
    00053   uint32_t blockSize,
    00054   q31_t * pResult,
    00055   uint32_t * pIndex)
    00056 {
    00057   q31_t maxVal, out;                             /* Temporary variables to store the output value. */
    00058   uint32_t blkCnt, outIndex;                     /* loop counter */
    00059
    00060   /* Initialise the index value to zero. */
    00061   outIndex = 0u;
    00062   /* Load first input value that act as reference value for comparision */
    00063   out = *pSrc++;
    00064
    00065   /* Loop over blockSize number of values */
    00066   blkCnt = (blockSize - 1u);
    00067
    00068 #ifndef ARM_MATH_CM0
    00069
    00070   /* Run the below code for Cortex-M4 and Cortex-M3 */
    00071
    00072   do
    00073   {
    00074     /* Initialize maxVal to the next consecutive values one by one */
    00075     maxVal = *pSrc++;
    00076
    00077     /* compare for the maximum value */
    00078     if(out < maxVal)
    00079     {
    00080       /* Update the maximum value and its index */
    00081       out = maxVal;
    00082       outIndex = blockSize - blkCnt;
    00083     }
    00084
    00085     /* Decrement the loop counter */
    00086     blkCnt--;
    00087
    00088   } while(blkCnt > 0u);
    00089
    00090 #else
    00091
    00092   /* Run the below code for Cortex-M0 */
    00093
    00094   while(blkCnt > 0u)
    00095   {
    00096     /* Initialize maxVal to the next consecutive values one by one */
    00097     maxVal = *pSrc++;
    00098
    00099     /* Compare for the maximum value */
    00100     if(out < maxVal)
    00101     {
    00102       /* Update the maximum value and its index */
    00103       out = maxVal;
    00104       outIndex = blockSize - blkCnt;
    00105     }
    00106
    00107     /* Decrement the loop counter */
    00108     blkCnt--;
    00109
    00110   }
    00111
    00112 #endif /* #ifndef ARM_MATH_CM0 */
    00113
    00114   /* Store the maximum value and its index into destination pointers */
    00115   *pResult = out;
    00116   *pIndex = outIndex;
    00117 }
    00118

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