/* ----------------------------------------------------------------------
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* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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*
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* $Date: 19. March 2015
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* $Revision: V.1.4.5
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*
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* Project: CMSIS DSP Library
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* Title: arm_mat_mult_fast_q31.c
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*
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* Description: Q31 matrix multiplication (fast variant).
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*
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* Target Processor: Cortex-M4/Cortex-M3
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* - Neither the name of ARM LIMITED nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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* -------------------------------------------------------------------- */
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#include "arm_math.h"
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/**
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* @ingroup groupMatrix
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*/
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/**
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* @addtogroup MatrixMult
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* @{
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*/
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/**
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* @brief Q31 matrix multiplication (fast variant) for Cortex-M3 and Cortex-M4
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* @param[in] *pSrcA points to the first input matrix structure
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* @param[in] *pSrcB points to the second input matrix structure
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* @param[out] *pDst points to output matrix structure
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* @return The function returns either
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* <code>ARM_MATH_SIZE_MISMATCH</code> or <code>ARM_MATH_SUCCESS</code> based on the outcome of size checking.
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*
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* @details
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* <b>Scaling and Overflow Behavior:</b>
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*
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* \par
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* The difference between the function arm_mat_mult_q31() and this fast variant is that
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* the fast variant use a 32-bit rather than a 64-bit accumulator.
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* The result of each 1.31 x 1.31 multiplication is truncated to
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* 2.30 format. These intermediate results are accumulated in a 32-bit register in 2.30
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* format. Finally, the accumulator is saturated and converted to a 1.31 result.
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*
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* \par
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* The fast version has the same overflow behavior as the standard version but provides
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* less precision since it discards the low 32 bits of each multiplication result.
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* In order to avoid overflows completely the input signals must be scaled down.
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* Scale down one of the input matrices by log2(numColsA) bits to
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* avoid overflows, as a total of numColsA additions are computed internally for each
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* output element.
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*
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* \par
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* See <code>arm_mat_mult_q31()</code> for a slower implementation of this function
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* which uses 64-bit accumulation to provide higher precision.
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*/
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arm_status arm_mat_mult_fast_q31(
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const arm_matrix_instance_q31 * pSrcA,
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const arm_matrix_instance_q31 * pSrcB,
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arm_matrix_instance_q31 * pDst)
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{
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q31_t *pIn1 = pSrcA->pData; /* input data matrix pointer A */
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q31_t *pIn2 = pSrcB->pData; /* input data matrix pointer B */
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q31_t *pInA = pSrcA->pData; /* input data matrix pointer A */
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// q31_t *pSrcB = pSrcB->pData; /* input data matrix pointer B */
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q31_t *pOut = pDst->pData; /* output data matrix pointer */
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q31_t *px; /* Temporary output data matrix pointer */
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q31_t sum; /* Accumulator */
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uint16_t numRowsA = pSrcA->numRows; /* number of rows of input matrix A */
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uint16_t numColsB = pSrcB->numCols; /* number of columns of input matrix B */
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uint16_t numColsA = pSrcA->numCols; /* number of columns of input matrix A */
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uint16_t col, i = 0u, j, row = numRowsA, colCnt; /* loop counters */
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arm_status status; /* status of matrix multiplication */
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q31_t inA1, inA2, inA3, inA4, inB1, inB2, inB3, inB4;
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#ifdef ARM_MATH_MATRIX_CHECK
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/* Check for matrix mismatch condition */
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if((pSrcA->numCols != pSrcB->numRows) ||
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(pSrcA->numRows != pDst->numRows) || (pSrcB->numCols != pDst->numCols))
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{
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/* Set status as ARM_MATH_SIZE_MISMATCH */
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status = ARM_MATH_SIZE_MISMATCH;
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}
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else
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#endif /* #ifdef ARM_MATH_MATRIX_CHECK */
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{
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/* The following loop performs the dot-product of each row in pSrcA with each column in pSrcB */
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/* row loop */
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do
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{
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/* Output pointer is set to starting address of the row being processed */
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px = pOut + i;
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/* For every row wise process, the column loop counter is to be initiated */
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col = numColsB;
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/* For every row wise process, the pIn2 pointer is set
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** to the starting address of the pSrcB data */
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pIn2 = pSrcB->pData;
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j = 0u;
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/* column loop */
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do
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{
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/* Set the variable sum, that acts as accumulator, to zero */
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sum = 0;
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/* Initiate the pointer pIn1 to point to the starting address of pInA */
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pIn1 = pInA;
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/* Apply loop unrolling and compute 4 MACs simultaneously. */
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colCnt = numColsA >> 2;
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/* matrix multiplication */
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while(colCnt > 0u)
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{
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/* c(m,n) = a(1,1)*b(1,1) + a(1,2) * b(2,1) + .... + a(m,p)*b(p,n) */
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/* Perform the multiply-accumulates */
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inB1 = *pIn2;
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pIn2 += numColsB;
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inA1 = pIn1[0];
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inA2 = pIn1[1];
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inB2 = *pIn2;
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pIn2 += numColsB;
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inB3 = *pIn2;
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pIn2 += numColsB;
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sum = (q31_t) ((((q63_t) sum << 32) + ((q63_t) inA1 * inB1)) >> 32);
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sum = (q31_t) ((((q63_t) sum << 32) + ((q63_t) inA2 * inB2)) >> 32);
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inA3 = pIn1[2];
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inA4 = pIn1[3];
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inB4 = *pIn2;
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pIn2 += numColsB;
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sum = (q31_t) ((((q63_t) sum << 32) + ((q63_t) inA3 * inB3)) >> 32);
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sum = (q31_t) ((((q63_t) sum << 32) + ((q63_t) inA4 * inB4)) >> 32);
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pIn1 += 4u;
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/* Decrement the loop counter */
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colCnt--;
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}
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/* If the columns of pSrcA is not a multiple of 4, compute any remaining output samples here.
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** No loop unrolling is used. */
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colCnt = numColsA % 0x4u;
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while(colCnt > 0u)
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{
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/* c(m,n) = a(1,1)*b(1,1) + a(1,2) * b(2,1) + .... + a(m,p)*b(p,n) */
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/* Perform the multiply-accumulates */
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sum = (q31_t) ((((q63_t) sum << 32) +
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((q63_t) * pIn1++ * (*pIn2))) >> 32);
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pIn2 += numColsB;
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/* Decrement the loop counter */
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colCnt--;
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}
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/* Convert the result from 2.30 to 1.31 format and store in destination buffer */
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*px++ = sum << 1;
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/* Update the pointer pIn2 to point to the starting address of the next column */
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j++;
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pIn2 = pSrcB->pData + j;
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/* Decrement the column loop counter */
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col--;
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} while(col > 0u);
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/* Update the pointer pInA to point to the starting address of the next row */
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i = i + numColsB;
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pInA = pInA + numColsA;
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/* Decrement the row loop counter */
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row--;
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} while(row > 0u);
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/* set status as ARM_MATH_SUCCESS */
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status = ARM_MATH_SUCCESS;
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}
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/* Return to application */
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return (status);
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}
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/**
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* @} end of MatrixMult group
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*/
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