lib/main/CMSIS/DSP/Source/BasicMathFunctions/arm_abs_q15.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_abs_q15.c
   4  * Description:  Q15 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  * @brief Q15 vector absolute value.
  42  * @param[in]       *pSrc points to the input buffer
  43  * @param[out]      *pDst points to the output buffer
  44  * @param[in]       blockSize number of samples in each vector
  45  * @return none.
  46  *
  47  * <b>Scaling and Overflow Behavior:</b>
  48  * \par
  49  * The function uses saturating arithmetic.
  50  * The Q15 value -1 (0x8000) will be saturated to the maximum allowable positive value 0x7FFF.
  51  */
  52
  53 void arm_abs_q15(
  54   q15_t * pSrc,
  55   q15_t * pDst,
  56   uint32_t blockSize)
  57 {
  58   uint32_t blkCnt;                               /* loop counter */
  59
  60 #if defined (ARM_MATH_DSP)
  61   __SIMD32_TYPE *simd;
  62
  63 /* Run the below code for Cortex-M4 and Cortex-M3 */
  64
  65   q15_t in1;                                     /* Input value1 */
  66   q15_t in2;                                     /* Input value2 */
  67
  68
  69   /*loop Unrolling */
  70   blkCnt = blockSize >> 2U;
  71
  72   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  73    ** a second loop below computes the remaining 1 to 3 samples. */
  74   simd = __SIMD32_CONST(pDst);
  75   while (blkCnt > 0U)
  76   {
  77     /* C = |A| */
  78     /* Read two inputs */
  79     in1 = *pSrc++;
  80     in2 = *pSrc++;
  81
  82
  83     /* Store the Absolute result in the destination buffer by packing the two values, in a single cycle */
  84 #ifndef  ARM_MATH_BIG_ENDIAN
  85     *simd++ =
  86       __PKHBT(((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)),
  87               ((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)), 16);
  88
  89 #else
  90
  91
  92     *simd++ =
  93       __PKHBT(((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)),
  94               ((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)), 16);
  95
  96 #endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */
  97
  98     in1 = *pSrc++;
  99     in2 = *pSrc++;
 100
 101
 102 #ifndef  ARM_MATH_BIG_ENDIAN
 103
 104     *simd++ =
 105       __PKHBT(((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)),
 106               ((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)), 16);
 107
 108 #else
 109
 110
 111     *simd++ =
 112       __PKHBT(((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)),
 113               ((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)), 16);
 114
 115 #endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */
 116
 117     /* Decrement the loop counter */
 118     blkCnt--;
 119   }
 120   pDst = (q15_t *)simd;
 121
 122   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 123    ** No loop unrolling is used. */
 124   blkCnt = blockSize % 0x4U;
 125
 126   while (blkCnt > 0U)
 127   {
 128     /* C = |A| */
 129     /* Read the input */
 130     in1 = *pSrc++;
 131
 132     /* Calculate absolute value of input and then store the result in the destination buffer. */
 133     *pDst++ = (in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1);
 134
 135     /* Decrement the loop counter */
 136     blkCnt--;
 137   }
 138
 139 #else
 140
 141   /* Run the below code for Cortex-M0 */
 142
 143   q15_t in;                                      /* Temporary input variable */
 144
 145   /* Initialize blkCnt with number of samples */
 146   blkCnt = blockSize;
 147
 148   while (blkCnt > 0U)
 149   {
 150     /* C = |A| */
 151     /* Read the input */
 152     in = *pSrc++;
 153
 154     /* Calculate absolute value of input and then store the result in the destination buffer. */
 155     *pDst++ = (in > 0) ? in : ((in == (q15_t) 0x8000) ? 0x7fff : -in);
 156
 157     /* Decrement the loop counter */
 158     blkCnt--;
 159   }
 160
 161 #endif /* #if defined (ARM_MATH_DSP) */
 162
 163 }
 164
 165 /**
 166  * @} end of BasicAbs group
 167  */