tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_abs_q31.c

   1 /* ----------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:                arm_abs_q31.c
   9 *
  10 * Description:  Q31 vector absolute value.
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13 *
  14 * Redistribution and use in source and binary forms, with or without
  15 * modification, are permitted provided that the following conditions
  16 * are met:
  17 *   - Redistributions of source code must retain the above copyright
  18 *     notice, this list of conditions and the following disclaimer.
  19 *   - Redistributions in binary form must reproduce the above copyright
  20 *     notice, this list of conditions and the following disclaimer in
  21 *     the documentation and/or other materials provided with the
  22 *     distribution.
  23 *   - Neither the name of ARM LIMITED nor the names of its contributors
  24 *     may be used to endorse or promote products derived from this
  25 *     software without specific prior written permission.
  26 *
  27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38 * POSSIBILITY OF SUCH DAMAGE.
  39 * -------------------------------------------------------------------- */
  40
  41 #include "arm_math.h"
  42
  43 /**
  44  * @ingroup groupMath
  45  */
  46
  47 /**
  48  * @addtogroup BasicAbs
  49  * @{
  50  */
  51
  52
  53 /**
  54  * @brief Q31 vector absolute value.
  55  * @param[in]       *pSrc points to the input buffer
  56  * @param[out]      *pDst points to the output buffer
  57  * @param[in]       blockSize number of samples in each vector
  58  * @return none.
  59  *
  60  * <b>Scaling and Overflow Behavior:</b>
  61  * \par
  62  * The function uses saturating arithmetic.
  63  * The Q31 value -1 (0x80000000) will be saturated to the maximum allowable positive value 0x7FFFFFFF.
  64  */
  65
  66 void arm_abs_q31(
  67   q31_t * pSrc,
  68   q31_t * pDst,
  69   uint32_t blockSize)
  70 {
  71   uint32_t blkCnt;                               /* loop counter */
  72   q31_t in;                                      /* Input value */
  73
  74 #ifndef ARM_MATH_CM0_FAMILY
  75
  76   /* Run the below code for Cortex-M4 and Cortex-M3 */
  77   q31_t in1, in2, in3, in4;
  78
  79   /*loop Unrolling */
  80   blkCnt = blockSize >> 2u;
  81
  82   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  83    ** a second loop below computes the remaining 1 to 3 samples. */
  84   while(blkCnt > 0u)
  85   {
  86     /* C = |A| */
  87     /* Calculate absolute of input (if -1 then saturated to 0x7fffffff) and then store the results in the destination buffer. */
  88     in1 = *pSrc++;
  89     in2 = *pSrc++;
  90     in3 = *pSrc++;
  91     in4 = *pSrc++;
  92
  93     *pDst++ = (in1 > 0) ? in1 : (q31_t)__QSUB(0, in1);
  94     *pDst++ = (in2 > 0) ? in2 : (q31_t)__QSUB(0, in2);
  95     *pDst++ = (in3 > 0) ? in3 : (q31_t)__QSUB(0, in3);
  96     *pDst++ = (in4 > 0) ? in4 : (q31_t)__QSUB(0, in4);
  97
  98     /* Decrement the loop counter */
  99     blkCnt--;
 100   }
 101
 102   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 103    ** No loop unrolling is used. */
 104   blkCnt = blockSize % 0x4u;
 105
 106 #else
 107
 108   /* Run the below code for Cortex-M0 */
 109
 110   /* Initialize blkCnt with number of samples */
 111   blkCnt = blockSize;
 112
 113 #endif /*   #ifndef ARM_MATH_CM0_FAMILY   */
 114
 115   while(blkCnt > 0u)
 116   {
 117     /* C = |A| */
 118     /* Calculate absolute value of the input (if -1 then saturated to 0x7fffffff) and then store the results in the destination buffer. */
 119     in = *pSrc++;
 120     *pDst++ = (in > 0) ? in : ((in == INT32_MIN) ? INT32_MAX : -in);
 121
 122     /* Decrement the loop counter */
 123     blkCnt--;
 124   }
 125
 126 }
 127
 128 /**
 129  * @} end of BasicAbs group
 130  */