lib/main/CMSIS/DSP/Source/BasicMathFunctions/arm_sub_f32.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_sub_f32.c
   4  * Description:  Floating-point vector subtraction.
   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 BasicSub Vector Subtraction
  37  *
  38  * Element-by-element subtraction of two vectors.
  39  *
  40  * <pre>
  41  *     pDst[n] = pSrcA[n] - pSrcB[n],   0 <= n < blockSize.
  42  * </pre>
  43  *
  44  * There are separate functions for floating-point, Q7, Q15, and Q31 data types.
  45  */
  46
  47 /**
  48  * @addtogroup BasicSub
  49  * @{
  50  */
  51
  52
  53 /**
  54  * @brief Floating-point vector subtraction.
  55  * @param[in]       *pSrcA points to the first input vector
  56  * @param[in]       *pSrcB points to the second input vector
  57  * @param[out]      *pDst points to the output vector
  58  * @param[in]       blockSize number of samples in each vector
  59  * @return none.
  60  */
  61
  62 void arm_sub_f32(
  63   float32_t * pSrcA,
  64   float32_t * pSrcB,
  65   float32_t * pDst,
  66   uint32_t blockSize)
  67 {
  68   uint32_t blkCnt;                               /* loop counter */
  69
  70 #if defined (ARM_MATH_DSP)
  71
  72 /* Run the below code for Cortex-M4 and Cortex-M3 */
  73   float32_t inA1, inA2, inA3, inA4;              /* temporary variables */
  74   float32_t inB1, inB2, inB3, inB4;              /* temporary variables */
  75
  76   /*loop Unrolling */
  77   blkCnt = blockSize >> 2U;
  78
  79   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  80    ** a second loop below computes the remaining 1 to 3 samples. */
  81   while (blkCnt > 0U)
  82   {
  83     /* C = A - B */
  84     /* Subtract and then store the results in the destination buffer. */
  85     /* Read 4 input samples from sourceA and sourceB */
  86     inA1 = *pSrcA;
  87     inB1 = *pSrcB;
  88     inA2 = *(pSrcA + 1);
  89     inB2 = *(pSrcB + 1);
  90     inA3 = *(pSrcA + 2);
  91     inB3 = *(pSrcB + 2);
  92     inA4 = *(pSrcA + 3);
  93     inB4 = *(pSrcB + 3);
  94
  95     /* dst = srcA - srcB */
  96     /* subtract and store the result */
  97     *pDst = inA1 - inB1;
  98     *(pDst + 1) = inA2 - inB2;
  99     *(pDst + 2) = inA3 - inB3;
 100     *(pDst + 3) = inA4 - inB4;
 101
 102
 103     /* Update pointers to process next sampels */
 104     pSrcA += 4U;
 105     pSrcB += 4U;
 106     pDst += 4U;
 107
 108     /* Decrement the loop counter */
 109     blkCnt--;
 110   }
 111
 112   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 113    ** No loop unrolling is used. */
 114   blkCnt = blockSize % 0x4U;
 115
 116 #else
 117
 118   /* Run the below code for Cortex-M0 */
 119
 120   /* Initialize blkCnt with number of samples */
 121   blkCnt = blockSize;
 122
 123 #endif /* #if defined (ARM_MATH_DSP) */
 124
 125   while (blkCnt > 0U)
 126   {
 127     /* C = A - B */
 128     /* Subtract and then store the results in the destination buffer. */
 129     *pDst++ = (*pSrcA++) - (*pSrcB++);
 130
 131     /* Decrement the loop counter */
 132     blkCnt--;
 133   }
 134 }
 135
 136 /**
 137  * @} end of BasicSub group
 138  */