1  /* ----------------------------------------------------------------------
  2   * Project:      CMSIS DSP Library
  3   * Title:        arm_abs_q15.c
  4   * Description:  Q15 vector absolute value
  5   *
  6   * $Date:        23 April 2021
  7   * $Revision:    V1.9.0
  8   *
  9   * Target Processor: Cortex-M and Cortex-A cores
 10   * -------------------------------------------------------------------- */
 11  /*
 12   * Copyright (C) 2010-2021 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 "dsp/basic_math_functions.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 vector
 43    @param[out]    pDst       points to the output vector
 44    @param[in]     blockSize  number of samples in each vector
 45    @return        none
 46  
 47    @par           Scaling and Overflow Behavior
 48                     The function uses saturating arithmetic.
 49                     The Q15 value -1 (0x8000) will be saturated to the maximum allowable positive value 0x7FFF.
 50   */
 51  
 52  #if defined(ARM_MATH_MVEI) && !defined(ARM_MATH_AUTOVECTORIZE)
 53  
 54  #include "arm_helium_utils.h"
 55  
 56  void arm_abs_q15(
 57      const q15_t * pSrc,
 58      q15_t * pDst,
 59      uint32_t blockSize)
 60  {
 61      uint32_t  blkCnt;           /* loop counters */
 62      q15x8_t vecSrc;
 63  
 64      /* Compute 8 outputs at a time */
 65      blkCnt = blockSize >> 3;
 66      while (blkCnt > 0U)
 67      {
 68          /*
 69           * C = |A|
 70           * Calculate absolute and then store the results in the destination buffer.
 71           */
 72          vecSrc = vld1q(pSrc);
 73          vst1q(pDst, vqabsq(vecSrc));
 74          /*
 75           * Decrement the blockSize loop counter
 76           */
 77          blkCnt--;
 78          /*
 79           * advance vector source and destination pointers
 80           */
 81          pSrc += 8;
 82          pDst += 8;
 83      }
 84      /*
 85       * tail
 86       */
 87      blkCnt = blockSize & 7;
 88      if (blkCnt > 0U)
 89      {
 90          mve_pred16_t p0 = vctp16q(blkCnt);
 91          vecSrc = vld1q(pSrc);
 92          vstrhq_p(pDst, vqabsq(vecSrc), p0);
 93      }
 94  }
 95  
 96  #else
 97  void arm_abs_q15(
 98    const q15_t * pSrc,
 99          q15_t * pDst,
100          uint32_t blockSize)
101  {
102          uint32_t blkCnt;                               /* Loop counter */
103          q15_t in;                                      /* Temporary input variable */
104  
105  #if defined (ARM_MATH_LOOPUNROLL)
106  
107    /* Loop unrolling: Compute 4 outputs at a time */
108    blkCnt = blockSize >> 2U;
109  
110    while (blkCnt > 0U)
111    {
112      /* C = |A| */
113  
114      /* Calculate absolute of input (if -1 then saturated to 0x7fff) and store result in destination buffer. */
115      in = *pSrc++;
116  #if defined (ARM_MATH_DSP)
117      *pDst++ = (in > 0) ? in : (q15_t)__QSUB16(0, in);
118  #else
119      *pDst++ = (in > 0) ? in : ((in == (q15_t) 0x8000) ? 0x7fff : -in);
120  #endif
121  
122      in = *pSrc++;
123  #if defined (ARM_MATH_DSP)
124      *pDst++ = (in > 0) ? in : (q15_t)__QSUB16(0, in);
125  #else
126      *pDst++ = (in > 0) ? in : ((in == (q15_t) 0x8000) ? 0x7fff : -in);
127  #endif
128  
129      in = *pSrc++;
130  #if defined (ARM_MATH_DSP)
131      *pDst++ = (in > 0) ? in : (q15_t)__QSUB16(0, in);
132  #else
133      *pDst++ = (in > 0) ? in : ((in == (q15_t) 0x8000) ? 0x7fff : -in);
134  #endif
135  
136      in = *pSrc++;
137  #if defined (ARM_MATH_DSP)
138      *pDst++ = (in > 0) ? in : (q15_t)__QSUB16(0, in);
139  #else
140      *pDst++ = (in > 0) ? in : ((in == (q15_t) 0x8000) ? 0x7fff : -in);
141  #endif
142  
143      /* Decrement loop counter */
144      blkCnt--;
145    }
146  
147    /* Loop unrolling: Compute remaining outputs */
148    blkCnt = blockSize % 0x4U;
149  
150  #else
151  
152    /* Initialize blkCnt with number of samples */
153    blkCnt = blockSize;
154  
155  #endif /* #if defined (ARM_MATH_LOOPUNROLL) */
156  
157    while (blkCnt > 0U)
158    {
159      /* C = |A| */
160  
161      /* Calculate absolute of input (if -1 then saturated to 0x7fff) and store result in destination buffer. */
162      in = *pSrc++;
163  #if defined (ARM_MATH_DSP)
164      *pDst++ = (in > 0) ? in : (q15_t)__QSUB16(0, in);
165  #else
166      *pDst++ = (in > 0) ? in : ((in == (q15_t) 0x8000) ? 0x7fff : -in);
167  #endif
168  
169      /* Decrement loop counter */
170      blkCnt--;
171    }
172  
173  }
174  #endif /* defined(ARM_MATH_MVEI) */
175  
176  /**
177    @} end of BasicAbs group
178   */