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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_mat_sub_q31.c
  4.  * Description:  Q31 matrix 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 groupMatrix
  33.  */
  34.  
  35. /**
  36.  * @addtogroup MatrixSub
  37.  * @{
  38.  */
  39.  
  40. /**
  41.  * @brief Q31 matrix subtraction.
  42.  * @param[in]       *pSrcA points to the first input matrix structure
  43.  * @param[in]       *pSrcB points to the second input matrix structure
  44.  * @param[out]      *pDst points to output matrix structure
  45.  * @return              The function returns either
  46.  * <code>ARM_MATH_SIZE_MISMATCH</code> or <code>ARM_MATH_SUCCESS</code> based on the outcome of size checking.
  47.  *
  48.  * <b>Scaling and Overflow Behavior:</b>
  49.  * \par
  50.  * The function uses saturating arithmetic.
  51.  * Results outside of the allowable Q31 range [0x80000000 0x7FFFFFFF] will be saturated.
  52.  */
  53.  
  54.  
  55. arm_status arm_mat_sub_q31(
  56.   const arm_matrix_instance_q31 * pSrcA,
  57.   const arm_matrix_instance_q31 * pSrcB,
  58.   arm_matrix_instance_q31 * pDst)
  59. {
  60.   q31_t *pIn1 = pSrcA->pData;                    /* input data matrix pointer A */
  61.   q31_t *pIn2 = pSrcB->pData;                    /* input data matrix pointer B */
  62.   q31_t *pOut = pDst->pData;                     /* output data matrix pointer */
  63.   q31_t inA1, inB1;                              /* temporary variables */
  64.  
  65. #if defined (ARM_MATH_DSP)
  66.  
  67.   q31_t inA2, inB2;                              /* temporary variables */
  68.   q31_t out1, out2;                              /* temporary variables */
  69.  
  70. #endif //      #if defined (ARM_MATH_DSP)
  71.  
  72.   uint32_t numSamples;                           /* total number of elements in the matrix  */
  73.   uint32_t blkCnt;                               /* loop counters */
  74.   arm_status status;                             /* status of matrix subtraction */
  75.  
  76.  
  77. #ifdef ARM_MATH_MATRIX_CHECK
  78.   /* Check for matrix mismatch condition  */
  79.   if ((pSrcA->numRows != pSrcB->numRows) ||
  80.      (pSrcA->numCols != pSrcB->numCols) ||
  81.      (pSrcA->numRows != pDst->numRows) || (pSrcA->numCols != pDst->numCols))
  82.   {
  83.     /* Set status as ARM_MATH_SIZE_MISMATCH */
  84.     status = ARM_MATH_SIZE_MISMATCH;
  85.   }
  86.   else
  87. #endif
  88.   {
  89.     /* Total number of samples in the input matrix */
  90.     numSamples = (uint32_t) pSrcA->numRows * pSrcA->numCols;
  91.  
  92. #if defined (ARM_MATH_DSP)
  93.  
  94.     /* Run the below code for Cortex-M4 and Cortex-M3 */
  95.  
  96.     /* Loop Unrolling */
  97.     blkCnt = numSamples >> 2U;
  98.  
  99.     /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  100.      ** a second loop below computes the remaining 1 to 3 samples. */
  101.     while (blkCnt > 0U)
  102.     {
  103.       /* C(m,n) = A(m,n) - B(m,n) */
  104.       /* Subtract, saturate and then store the results in the destination buffer. */
  105.       /* Read values from source A */
  106.       inA1 = pIn1[0];
  107.  
  108.       /* Read values from source B */
  109.       inB1 = pIn2[0];
  110.  
  111.       /* Read values from source A */
  112.       inA2 = pIn1[1];
  113.  
  114.       /* Subtract and saturate */
  115.       out1 = __QSUB(inA1, inB1);
  116.  
  117.       /* Read values from source B */
  118.       inB2 = pIn2[1];
  119.  
  120.       /* Read values from source A */
  121.       inA1 = pIn1[2];
  122.  
  123.       /* Subtract and saturate */
  124.       out2 = __QSUB(inA2, inB2);
  125.  
  126.       /* Read values from source B */
  127.       inB1 = pIn2[2];
  128.  
  129.       /* Store result in destination */
  130.       pOut[0] = out1;
  131.       pOut[1] = out2;
  132.  
  133.       /* Read values from source A */
  134.       inA2 = pIn1[3];
  135.  
  136.       /* Read values from source B */
  137.       inB2 = pIn2[3];
  138.  
  139.       /* Subtract and saturate */
  140.       out1 = __QSUB(inA1, inB1);
  141.  
  142.       /* Subtract and saturate */
  143.       out2 = __QSUB(inA2, inB2);
  144.  
  145.       /* Store result in destination */
  146.       pOut[2] = out1;
  147.       pOut[3] = out2;
  148.  
  149.       /* update pointers to process next samples */
  150.       pIn1 += 4U;
  151.       pIn2 += 4U;
  152.       pOut += 4U;
  153.  
  154.       /* Decrement the loop counter */
  155.       blkCnt--;
  156.     }
  157.  
  158.     /* If the numSamples is not a multiple of 4, compute any remaining output samples here.
  159.      ** No loop unrolling is used. */
  160.     blkCnt = numSamples % 0x4U;
  161.  
  162. #else
  163.  
  164.     /* Run the below code for Cortex-M0 */
  165.  
  166.     /* Initialize blkCnt with number of samples */
  167.     blkCnt = numSamples;
  168.  
  169. #endif /* #if defined (ARM_MATH_DSP) */
  170.  
  171.     while (blkCnt > 0U)
  172.     {
  173.       /* C(m,n) = A(m,n) - B(m,n) */
  174.       /* Subtract, saturate and then store the results in the destination buffer. */
  175.       inA1 = *pIn1++;
  176.       inB1 = *pIn2++;
  177.  
  178.       inA1 = __QSUB(inA1, inB1);
  179.  
  180.       *pOut++ = inA1;
  181.  
  182.       /* Decrement the loop counter */
  183.       blkCnt--;
  184.     }
  185.  
  186.     /* Set status as ARM_MATH_SUCCESS */
  187.     status = ARM_MATH_SUCCESS;
  188.   }
  189.  
  190.   /* Return to application */
  191.   return (status);
  192. }
  193.  
  194. /**
  195.  * @} end of MatrixSub group
  196.  */
  197.