lib/main/CMSIS/DSP/Source/BasicMathFunctions/arm_abs_q31.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_abs_q31.c
   4  * Description:  Q31 vector absolute value
   5  *
   6  * $Date:        27. January 2017
   7  * $Revision:    V.1.5.1
   8  *
   9  * Target Processor: Cortex-M cores
  10  * -------------------------------------------------------------------- */
  11 /*
  12  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
  13  *
  14  * SPDX-License-Identifier: Apache-2.0
  15  *
  16  * Licensed under the Apache License, Version 2.0 (the License); you may
  17  * not use this file except in compliance with the License.
  18  * You may obtain a copy of the License at
  19  *
  20  * www.apache.org/licenses/LICENSE-2.0
  21  *
  22  * Unless required by applicable law or agreed to in writing, software
  23  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
  24  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  25  * See the License for the specific language governing permissions and
  26  * limitations under the License.
  27  */
  28
  29 #include "arm_math.h"
  30
  31 /**
  32  * @ingroup groupMath
  33  */
  34
  35 /**
  36  * @addtogroup BasicAbs
  37  * @{
  38  */
  39
  40
  41 /**
  42  * @brief Q31 vector absolute value.
  43  * @param[in]       *pSrc points to the input buffer
  44  * @param[out]      *pDst points to the output buffer
  45  * @param[in]       blockSize number of samples in each vector
  46  * @return none.
  47  *
  48  * <b>Scaling and Overflow Behavior:</b>
  49  * \par
  50  * The function uses saturating arithmetic.
  51  * The Q31 value -1 (0x80000000) will be saturated to the maximum allowable positive value 0x7FFFFFFF.
  52  */
  53
  54 void arm_abs_q31(
  55   q31_t * pSrc,
  56   q31_t * pDst,
  57   uint32_t blockSize)
  58 {
  59   uint32_t blkCnt;                               /* loop counter */
  60   q31_t in;                                      /* Input value */
  61
  62 #if defined (ARM_MATH_DSP)
  63
  64   /* Run the below code for Cortex-M4 and Cortex-M3 */
  65   q31_t in1, in2, in3, in4;
  66
  67   /*loop Unrolling */
  68   blkCnt = blockSize >> 2U;
  69
  70   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  71    ** a second loop below computes the remaining 1 to 3 samples. */
  72   while (blkCnt > 0U)
  73   {
  74     /* C = |A| */
  75     /* Calculate absolute of input (if -1 then saturated to 0x7fffffff) and then store the results in the destination buffer. */
  76     in1 = *pSrc++;
  77     in2 = *pSrc++;
  78     in3 = *pSrc++;
  79     in4 = *pSrc++;
  80
  81     *pDst++ = (in1 > 0) ? in1 : (q31_t)__QSUB(0, in1);
  82     *pDst++ = (in2 > 0) ? in2 : (q31_t)__QSUB(0, in2);
  83     *pDst++ = (in3 > 0) ? in3 : (q31_t)__QSUB(0, in3);
  84     *pDst++ = (in4 > 0) ? in4 : (q31_t)__QSUB(0, in4);
  85
  86     /* Decrement the loop counter */
  87     blkCnt--;
  88   }
  89
  90   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  91    ** No loop unrolling is used. */
  92   blkCnt = blockSize % 0x4U;
  93
  94 #else
  95
  96   /* Run the below code for Cortex-M0 */
  97
  98   /* Initialize blkCnt with number of samples */
  99   blkCnt = blockSize;
 100
 101 #endif /*   #if defined (ARM_MATH_DSP)   */
 102
 103   while (blkCnt > 0U)
 104   {
 105     /* C = |A| */
 106     /* Calculate absolute value of the input (if -1 then saturated to 0x7fffffff) and then store the results in the destination buffer. */
 107     in = *pSrc++;
 108     *pDst++ = (in > 0) ? in : ((in == INT32_MIN) ? INT32_MAX : -in);
 109
 110     /* Decrement the loop counter */
 111     blkCnt--;
 112   }
 113
 114 }
 115
 116 /**
 117  * @} end of BasicAbs group
 118  */