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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_negate_f32.c
  4.  * Description:  Negates floating-point vectors
  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.  * @defgroup negate Vector Negate
  37.  *
  38.  * Negates the elements of a vector.
  39.  *
  40.  * <pre>
  41.  *     pDst[n] = -pSrc[n],   0 <= n < blockSize.
  42.  * </pre>
  43.  *
  44.  * The functions support in-place computation allowing the source and
  45.  * destination pointers to reference the same memory buffer.
  46.  * There are separate functions for floating-point, Q7, Q15, and Q31 data types.
  47.  */
  48.  
  49. /**
  50.  * @addtogroup negate
  51.  * @{
  52.  */
  53.  
  54. /**
  55.  * @brief  Negates the elements of a floating-point vector.
  56.  * @param[in]  *pSrc points to the input vector
  57.  * @param[out]  *pDst points to the output vector
  58.  * @param[in]  blockSize number of samples in the vector
  59.  * @return none.
  60.  */
  61.  
  62. void arm_negate_f32(
  63.   float32_t * pSrc,
  64.   float32_t * pDst,
  65.   uint32_t blockSize)
  66. {
  67.   uint32_t blkCnt;                               /* loop counter */
  68.  
  69.  
  70. #if defined (ARM_MATH_DSP)
  71.  
  72. /* Run the below code for Cortex-M4 and Cortex-M3 */
  73.   float32_t in1, in2, in3, in4;                  /* temporary variables */
  74.  
  75.   /*loop Unrolling */
  76.   blkCnt = blockSize >> 2U;
  77.  
  78.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  79.    ** a second loop below computes the remaining 1 to 3 samples. */
  80.   while (blkCnt > 0U)
  81.   {
  82.     /* read inputs from source */
  83.     in1 = *pSrc;
  84.     in2 = *(pSrc + 1);
  85.     in3 = *(pSrc + 2);
  86.     in4 = *(pSrc + 3);
  87.  
  88.     /* negate the input */
  89.     in1 = -in1;
  90.     in2 = -in2;
  91.     in3 = -in3;
  92.     in4 = -in4;
  93.  
  94.     /* store the result to destination */
  95.     *pDst = in1;
  96.     *(pDst + 1) = in2;
  97.     *(pDst + 2) = in3;
  98.     *(pDst + 3) = in4;
  99.  
  100.     /* update pointers to process next samples */
  101.     pSrc += 4U;
  102.     pDst += 4U;
  103.  
  104.     /* Decrement the loop counter */
  105.     blkCnt--;
  106.   }
  107.  
  108.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  109.    ** No loop unrolling is used. */
  110.   blkCnt = blockSize % 0x4U;
  111.  
  112. #else
  113.  
  114.   /* Run the below code for Cortex-M0 */
  115.  
  116.   /* Initialize blkCnt with number of samples */
  117.   blkCnt = blockSize;
  118.  
  119. #endif /* #if defined (ARM_MATH_DSP) */
  120.  
  121.   while (blkCnt > 0U)
  122.   {
  123.     /* C = -A */
  124.     /* Negate and then store the results in the destination buffer. */
  125.     *pDst++ = -*pSrc++;
  126.  
  127.     /* Decrement the loop counter */
  128.     blkCnt--;
  129.   }
  130. }
  131.  
  132. /**
  133.  * @} end of negate group
  134.  */
  135.