tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_negate_f32.c

   1 /* ----------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:                arm_negate_f32.c
   9 *
  10 * Description:  Negates floating-point vectors.
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13 *
  14 * Redistribution and use in source and binary forms, with or without
  15 * modification, are permitted provided that the following conditions
  16 * are met:
  17 *   - Redistributions of source code must retain the above copyright
  18 *     notice, this list of conditions and the following disclaimer.
  19 *   - Redistributions in binary form must reproduce the above copyright
  20 *     notice, this list of conditions and the following disclaimer in
  21 *     the documentation and/or other materials provided with the
  22 *     distribution.
  23 *   - Neither the name of ARM LIMITED nor the names of its contributors
  24 *     may be used to endorse or promote products derived from this
  25 *     software without specific prior written permission.
  26 *
  27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38 * POSSIBILITY OF SUCH DAMAGE.
  39 * ---------------------------------------------------------------------------- */
  40
  41 #include "arm_math.h"
  42
  43 /**
  44  * @ingroup groupMath
  45  */
  46
  47 /**
  48  * @defgroup negate Vector Negate
  49  *
  50  * Negates the elements of a vector.
  51  *
  52  * <pre>
  53  *     pDst[n] = -pSrc[n],   0 <= n < blockSize.
  54  * </pre>
  55  *
  56  * The functions support in-place computation allowing the source and
  57  * destination pointers to reference the same memory buffer.
  58  * There are separate functions for floating-point, Q7, Q15, and Q31 data types.
  59  */
  60
  61 /**
  62  * @addtogroup negate
  63  * @{
  64  */
  65
  66 /**
  67  * @brief  Negates the elements of a floating-point vector.
  68  * @param[in]  *pSrc points to the input vector
  69  * @param[out]  *pDst points to the output vector
  70  * @param[in]  blockSize number of samples in the vector
  71  * @return none.
  72  */
  73
  74 void arm_negate_f32(
  75   float32_t * pSrc,
  76   float32_t * pDst,
  77   uint32_t blockSize)
  78 {
  79   uint32_t blkCnt;                               /* loop counter */
  80
  81
  82 #ifndef ARM_MATH_CM0_FAMILY
  83
  84 /* Run the below code for Cortex-M4 and Cortex-M3 */
  85   float32_t in1, in2, in3, in4;                  /* temporary variables */
  86
  87   /*loop Unrolling */
  88   blkCnt = blockSize >> 2u;
  89
  90   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  91    ** a second loop below computes the remaining 1 to 3 samples. */
  92   while(blkCnt > 0u)
  93   {
  94     /* read inputs from source */
  95     in1 = *pSrc;
  96     in2 = *(pSrc + 1);
  97     in3 = *(pSrc + 2);
  98     in4 = *(pSrc + 3);
  99
 100     /* negate the input */
 101     in1 = -in1;
 102     in2 = -in2;
 103     in3 = -in3;
 104     in4 = -in4;
 105
 106     /* store the result to destination */
 107     *pDst = in1;
 108     *(pDst + 1) = in2;
 109     *(pDst + 2) = in3;
 110     *(pDst + 3) = in4;
 111
 112     /* update pointers to process next samples */
 113     pSrc += 4u;
 114     pDst += 4u;
 115
 116     /* Decrement the loop counter */
 117     blkCnt--;
 118   }
 119
 120   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 121    ** No loop unrolling is used. */
 122   blkCnt = blockSize % 0x4u;
 123
 124 #else
 125
 126   /* Run the below code for Cortex-M0 */
 127
 128   /* Initialize blkCnt with number of samples */
 129   blkCnt = blockSize;
 130
 131 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 132
 133   while(blkCnt > 0u)
 134   {
 135     /* C = -A */
 136     /* Negate and then store the results in the destination buffer. */
 137     *pDst++ = -*pSrc++;
 138
 139     /* Decrement the loop counter */
 140     blkCnt--;
 141   }
 142 }
 143
 144 /**
 145  * @} end of negate group
 146  */