arm_mat_sub_q15.c

00001 /* ----------------------------------------------------------------------
00002  * Project:      CMSIS DSP Library
00003  * Title:        arm_mat_sub_q15.c
00004  * Description:  Q15 Matrix subtraction
00005  *
00006  * $Date:        27. January 2017
00007  * $Revision:    V.1.5.1
00008  *
00009  * Target Processor: Cortex-M cores
00010  * -------------------------------------------------------------------- */
00011 /*
00012  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
00013  *
00014  * SPDX-License-Identifier: Apache-2.0
00015  *
00016  * Licensed under the Apache License, Version 2.0 (the License); you may
00017  * not use this file except in compliance with the License.
00018  * You may obtain a copy of the License at
00019  *
00020  * www.apache.org/licenses/LICENSE-2.0
00021  *
00022  * Unless required by applicable law or agreed to in writing, software
00023  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
00024  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00025  * See the License for the specific language governing permissions and
00026  * limitations under the License.
00027  */
00028 
00029 #include "arm_math.h"
00030 
00031 /**
00032  * @ingroup groupMatrix
00033  */
00034 
00035 /**
00036  * @addtogroup MatrixSub
00037  * @{
00038  */
00039 
00040 /**
00041  * @brief Q15 matrix subtraction.
00042  * @param[in]       *pSrcA points to the first input matrix structure
00043  * @param[in]       *pSrcB points to the second input matrix structure
00044  * @param[out]      *pDst points to output matrix structure
00045  * @return          The function returns either
00046  * <code>ARM_MATH_SIZE_MISMATCH</code> or <code>ARM_MATH_SUCCESS</code> based on the outcome of size checking.
00047  *
00048  * <b>Scaling and Overflow Behavior:</b>
00049  * \par
00050  * The function uses saturating arithmetic.
00051  * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
00052  */
00053 
00054 arm_status arm_mat_sub_q15(
00055   const arm_matrix_instance_q15 * pSrcA,
00056   const arm_matrix_instance_q15 * pSrcB,
00057   arm_matrix_instance_q15 * pDst)
00058 {
00059   q15_t *pInA = pSrcA->pData;                    /* input data matrix pointer A */
00060   q15_t *pInB = pSrcB->pData;                    /* input data matrix pointer B */
00061   q15_t *pOut = pDst->pData;                     /* output data matrix pointer */
00062   uint32_t numSamples;                           /* total number of elements in the matrix */
00063   uint32_t blkCnt;                               /* loop counters  */
00064   arm_status status;                             /* status of matrix subtraction  */
00065 
00066 
00067 #ifdef ARM_MATH_MATRIX_CHECK
00068 
00069 
00070   /* Check for matrix mismatch condition */
00071   if ((pSrcA->numRows != pSrcB->numRows) ||
00072      (pSrcA->numCols != pSrcB->numCols) ||
00073      (pSrcA->numRows != pDst->numRows) || (pSrcA->numCols != pDst->numCols))
00074   {
00075     /* Set status as ARM_MATH_SIZE_MISMATCH */
00076     status = ARM_MATH_SIZE_MISMATCH;
00077   }
00078   else
00079 #endif /*    #ifdef ARM_MATH_MATRIX_CHECK    */
00080 
00081   {
00082     /* Total number of samples in the input matrix */
00083     numSamples = (uint32_t) pSrcA->numRows * pSrcA->numCols;
00084 
00085 #if defined (ARM_MATH_DSP)
00086 
00087     /* Run the below code for Cortex-M4 and Cortex-M3 */
00088 
00089     /* Apply loop unrolling */
00090     blkCnt = numSamples >> 2U;
00091 
00092     /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
00093      ** a second loop below computes the remaining 1 to 3 samples. */
00094     while (blkCnt > 0U)
00095     {
00096       /* C(m,n) = A(m,n) - B(m,n) */
00097       /* Subtract, Saturate and then store the results in the destination buffer. */
00098       *__SIMD32(pOut)++ = __QSUB16(*__SIMD32(pInA)++, *__SIMD32(pInB)++);
00099       *__SIMD32(pOut)++ = __QSUB16(*__SIMD32(pInA)++, *__SIMD32(pInB)++);
00100 
00101       /* Decrement the loop counter */
00102       blkCnt--;
00103     }
00104 
00105     /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
00106      ** No loop unrolling is used. */
00107     blkCnt = numSamples % 0x4U;
00108 
00109     while (blkCnt > 0U)
00110     {
00111       /* C(m,n) = A(m,n) - B(m,n) */
00112       /* Subtract and then store the results in the destination buffer. */
00113       *pOut++ = (q15_t) __QSUB16(*pInA++, *pInB++);
00114 
00115       /* Decrement the loop counter */
00116       blkCnt--;
00117     }
00118 
00119 #else
00120 
00121     /* Run the below code for Cortex-M0 */
00122 
00123     /* Initialize blkCnt with number of samples */
00124     blkCnt = numSamples;
00125 
00126     while (blkCnt > 0U)
00127     {
00128       /* C(m,n) = A(m,n) - B(m,n) */
00129       /* Subtract and then store the results in the destination buffer. */
00130       *pOut++ = (q15_t) __SSAT(((q31_t) * pInA++ - *pInB++), 16);
00131 
00132       /* Decrement the loop counter */
00133       blkCnt--;
00134     }
00135 
00136 #endif /* #if defined (ARM_MATH_DSP) */
00137 
00138     /* Set status as ARM_MATH_SUCCESS */
00139     status = ARM_MATH_SUCCESS;
00140   }
00141 
00142   /* Return to application */
00143   return (status);
00144 }
00145 
00146 /**
00147  * @} end of MatrixSub group
00148  */
00149