lib/main/CMSIS/DSP/Source/BasicMathFunctions/arm_negate_f32.c

   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  */