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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_mat_sub_q15.c
  4.  * Description:  Q15 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 Q15 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 Q15 range [0x8000 0x7FFF] will be saturated.
  52.  */
  53.  
  54. arm_status arm_mat_sub_q15(
  55.   const arm_matrix_instance_q15 * pSrcA,
  56.   const arm_matrix_instance_q15 * pSrcB,
  57.   arm_matrix_instance_q15 * pDst)
  58. {
  59.   q15_t *pInA = pSrcA->pData;                    /* input data matrix pointer A */
  60.   q15_t *pInB = pSrcB->pData;                    /* input data matrix pointer B */
  61.   q15_t *pOut = pDst->pData;                     /* output data matrix pointer */
  62.   uint32_t numSamples;                           /* total number of elements in the matrix */
  63.   uint32_t blkCnt;                               /* loop counters  */
  64.   arm_status status;                             /* status of matrix subtraction  */
  65.  
  66.  
  67. #ifdef ARM_MATH_MATRIX_CHECK
  68.  
  69.  
  70.   /* Check for matrix mismatch condition */
  71.   if ((pSrcA->numRows != pSrcB->numRows) ||
  72.      (pSrcA->numCols != pSrcB->numCols) ||
  73.      (pSrcA->numRows != pDst->numRows) || (pSrcA->numCols != pDst->numCols))
  74.   {
  75.     /* Set status as ARM_MATH_SIZE_MISMATCH */
  76.     status = ARM_MATH_SIZE_MISMATCH;
  77.   }
  78.   else
  79. #endif /*    #ifdef ARM_MATH_MATRIX_CHECK    */
  80.  
  81.   {
  82.     /* Total number of samples in the input matrix */
  83.     numSamples = (uint32_t) pSrcA->numRows * pSrcA->numCols;
  84.  
  85. #if defined (ARM_MATH_DSP)
  86.  
  87.     /* Run the below code for Cortex-M4 and Cortex-M3 */
  88.  
  89.     /* Apply loop unrolling */
  90.     blkCnt = numSamples >> 2U;
  91.  
  92.     /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  93.      ** a second loop below computes the remaining 1 to 3 samples. */
  94.     while (blkCnt > 0U)
  95.     {
  96.       /* C(m,n) = A(m,n) - B(m,n) */
  97.       /* Subtract, Saturate and then store the results in the destination buffer. */
  98.       *__SIMD32(pOut)++ = __QSUB16(*__SIMD32(pInA)++, *__SIMD32(pInB)++);
  99.       *__SIMD32(pOut)++ = __QSUB16(*__SIMD32(pInA)++, *__SIMD32(pInB)++);
  100.  
  101.       /* Decrement the loop counter */
  102.       blkCnt--;
  103.     }
  104.  
  105.     /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  106.      ** No loop unrolling is used. */
  107.     blkCnt = numSamples % 0x4U;
  108.  
  109.     while (blkCnt > 0U)
  110.     {
  111.       /* C(m,n) = A(m,n) - B(m,n) */
  112.       /* Subtract and then store the results in the destination buffer. */
  113.       *pOut++ = (q15_t) __QSUB16(*pInA++, *pInB++);
  114.  
  115.       /* Decrement the loop counter */
  116.       blkCnt--;
  117.     }
  118.  
  119. #else
  120.  
  121.     /* Run the below code for Cortex-M0 */
  122.  
  123.     /* Initialize blkCnt with number of samples */
  124.     blkCnt = numSamples;
  125.  
  126.     while (blkCnt > 0U)
  127.     {
  128.       /* C(m,n) = A(m,n) - B(m,n) */
  129.       /* Subtract and then store the results in the destination buffer. */
  130.       *pOut++ = (q15_t) __SSAT(((q31_t) * pInA++ - *pInB++), 16);
  131.  
  132.       /* Decrement the loop counter */
  133.       blkCnt--;
  134.     }
  135.  
  136. #endif /* #if defined (ARM_MATH_DSP) */
  137.  
  138.     /* Set status as ARM_MATH_SUCCESS */
  139.     status = ARM_MATH_SUCCESS;
  140.   }
  141.  
  142.   /* Return to application */
  143.   return (status);
  144. }
  145.  
  146. /**
  147.  * @} end of MatrixSub group
  148.  */
  149.