lib/main/CMSIS/DSP/Source/BasicMathFunctions/arm_negate_q31.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_negate_q31.c
   4  * Description:  Negates Q31 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  * @addtogroup negate
  37  * @{
  38  */
  39
  40 /**
  41  * @brief  Negates the elements of a Q31 vector.
  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 the vector
  45  * @return none.
  46  *
  47  * <b>Scaling and Overflow Behavior:</b>
  48  * \par
  49  * The function uses saturating arithmetic.
  50  * The Q31 value -1 (0x80000000) will be saturated to the maximum allowable positive value 0x7FFFFFFF.
  51  */
  52
  53 void arm_negate_q31(
  54   q31_t * pSrc,
  55   q31_t * pDst,
  56   uint32_t blockSize)
  57 {
  58   q31_t in;                                      /* Temporary variable */
  59   uint32_t blkCnt;                               /* loop counter */
  60
  61 #if defined (ARM_MATH_DSP)
  62
  63 /* Run the below code for Cortex-M4 and Cortex-M3 */
  64   q31_t in1, in2, in3, in4;
  65
  66   /*loop Unrolling */
  67   blkCnt = blockSize >> 2U;
  68
  69   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  70    ** a second loop below computes the remaining 1 to 3 samples. */
  71   while (blkCnt > 0U)
  72   {
  73     /* C = -A */
  74     /* Negate and then store the results in the destination buffer. */
  75     in1 = *pSrc++;
  76     in2 = *pSrc++;
  77     in3 = *pSrc++;
  78     in4 = *pSrc++;
  79
  80     *pDst++ = __QSUB(0, in1);
  81     *pDst++ = __QSUB(0, in2);
  82     *pDst++ = __QSUB(0, in3);
  83     *pDst++ = __QSUB(0, in4);
  84
  85     /* Decrement the loop counter */
  86     blkCnt--;
  87   }
  88
  89   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  90    ** No loop unrolling is used. */
  91   blkCnt = blockSize % 0x4U;
  92
  93 #else
  94
  95   /* Run the below code for Cortex-M0 */
  96
  97   /* Initialize blkCnt with number of samples */
  98   blkCnt = blockSize;
  99
 100 #endif /* #if defined (ARM_MATH_DSP) */
 101
 102
 103   while (blkCnt > 0U)
 104   {
 105     /* C = -A */
 106     /* Negate and then store the result in the destination buffer. */
 107     in = *pSrc++;
 108     *pDst++ = (in == INT32_MIN) ? INT32_MAX : -in;
 109
 110     /* Decrement the loop counter */
 111     blkCnt--;
 112   }
 113 }
 114
 115 /**
 116  * @} end of negate group
 117  */