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  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.  */
  168.