/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date: 15. July 2011
* $Revision: V1.0.10
*
* Project: CMSIS DSP Library
* Title: arm_mat_mult_fast_q31.c
*
* Description: Q31 matrix multiplication (fast variant).
*
* Target Processor: Cortex-M4/Cortex-M3
*
* Version 1.0.10 2011/7/15
* Big Endian support added and Merged M0 and M3/M4 Source code.
*
* Version 1.0.3 2010/11/29
* Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.2 2010/11/11
* Documentation updated.
*
* Version 1.0.1 2010/10/05
* Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20
* Production release and review comments incorporated.
* -------------------------------------------------------------------- */
#include "arm_math.h"
/**
* @ingroup groupMatrix
*/
/**
* @addtogroup MatrixMult
* @{
*/
/**
* @brief Q31 matrix multiplication (fast variant) for Cortex-M3 and Cortex-M4
* @param[in] *pSrcA points to the first input matrix structure
* @param[in] *pSrcB points to the second input matrix structure
* @param[out] *pDst points to output matrix structure
* @return The function returns either
* ARM_MATH_SIZE_MISMATCH or ARM_MATH_SUCCESS based on the outcome of size checking.
*
* @details
* Scaling and Overflow Behavior:
*
* \par
* The difference between the function arm_mat_mult_q31() and this fast variant is that
* the fast variant use a 32-bit rather than a 64-bit accumulator.
* The result of each 1.31 x 1.31 multiplication is truncated to
* 2.30 format. These intermediate results are accumulated in a 32-bit register in 2.30
* format. Finally, the accumulator is saturated and converted to a 1.31 result.
*
* \par
* The fast version has the same overflow behavior as the standard version but provides
* less precision since it discards the low 32 bits of each multiplication result.
* In order to avoid overflows completely the input signals must be scaled down.
* Scale down one of the input matrices by log2(numColsA) bits to
* avoid overflows, as a total of numColsA additions are computed internally for each
* output element.
*
* \par
* See arm_mat_mult_q31() for a slower implementation of this function
* which uses 64-bit accumulation to provide higher precision.
*/
arm_status arm_mat_mult_fast_q31(
const arm_matrix_instance_q31 * pSrcA,
const arm_matrix_instance_q31 * pSrcB,
arm_matrix_instance_q31 * pDst)
{
q31_t *pIn1 = pSrcA->pData; /* input data matrix pointer A */
q31_t *pIn2 = pSrcB->pData; /* input data matrix pointer B */
q31_t *pInA = pSrcA->pData; /* input data matrix pointer A */
// q31_t *pSrcB = pSrcB->pData; /* input data matrix pointer B */
q31_t *pOut = pDst->pData; /* output data matrix pointer */
q31_t *px; /* Temporary output data matrix pointer */
q31_t sum; /* Accumulator */
uint16_t numRowsA = pSrcA->numRows; /* number of rows of input matrix A */
uint16_t numColsB = pSrcB->numCols; /* number of columns of input matrix B */
uint16_t numColsA = pSrcA->numCols; /* number of columns of input matrix A */
uint16_t col, i = 0u, j, row = numRowsA, colCnt; /* loop counters */
arm_status status; /* status of matrix multiplication */
#ifdef ARM_MATH_MATRIX_CHECK
/* Check for matrix mismatch condition */
if((pSrcA->numCols != pSrcB->numRows) ||
(pSrcA->numRows != pDst->numRows) || (pSrcB->numCols != pDst->numCols))
{
/* Set status as ARM_MATH_SIZE_MISMATCH */
status = ARM_MATH_SIZE_MISMATCH;
}
else
#endif /* #ifdef ARM_MATH_MATRIX_CHECK */
{
/* The following loop performs the dot-product of each row in pSrcA with each column in pSrcB */
/* row loop */
do
{
/* Output pointer is set to starting address of the row being processed */
px = pOut + i;
/* For every row wise process, the column loop counter is to be initiated */
col = numColsB;
/* For every row wise process, the pIn2 pointer is set
** to the starting address of the pSrcB data */
pIn2 = pSrcB->pData;
j = 0u;
/* column loop */
do
{
/* Set the variable sum, that acts as accumulator, to zero */
sum = 0;
/* Initiate the pointer pIn1 to point to the starting address of pInA */
pIn1 = pInA;
/* Apply loop unrolling and compute 4 MACs simultaneously. */
colCnt = numColsA >> 2;
/* matrix multiplication */
while(colCnt > 0u)
{
/* c(m,n) = a(1,1)*b(1,1) + a(1,2) * b(2,1) + .... + a(m,p)*b(p,n) */
/* Perform the multiply-accumulates */
sum = (q31_t) ((((q63_t) sum << 32) +
((q63_t) * pIn1++ * (*pIn2))) >> 32);
pIn2 += numColsB;
sum = (q31_t) ((((q63_t) sum << 32) +
((q63_t) * pIn1++ * (*pIn2))) >> 32);
pIn2 += numColsB;
sum = (q31_t) ((((q63_t) sum << 32) +
((q63_t) * pIn1++ * (*pIn2))) >> 32);
pIn2 += numColsB;
sum = (q31_t) ((((q63_t) sum << 32) +
((q63_t) * pIn1++ * (*pIn2))) >> 32);
pIn2 += numColsB;
/* Decrement the loop counter */
colCnt--;
}
/* If the columns of pSrcA is not a multiple of 4, compute any remaining output samples here.
** No loop unrolling is used. */
colCnt = numColsA % 0x4u;
while(colCnt > 0u)
{
/* c(m,n) = a(1,1)*b(1,1) + a(1,2) * b(2,1) + .... + a(m,p)*b(p,n) */
/* Perform the multiply-accumulates */
sum = (q31_t) ((((q63_t) sum << 32) +
((q63_t) * pIn1++ * (*pIn2))) >> 32);
pIn2 += numColsB;
/* Decrement the loop counter */
colCnt--;
}
/* Convert the result from 2.30 to 1.31 format and store in destination buffer */
*px++ = sum << 1;
/* Update the pointer pIn2 to point to the starting address of the next column */
j++;
pIn2 = pSrcB->pData + j;
/* Decrement the column loop counter */
col--;
} while(col > 0u);
/* Update the pointer pInA to point to the starting address of the next row */
i = i + numColsB;
pInA = pInA + numColsA;
/* Decrement the row loop counter */
row--;
} while(row > 0u);
/* set status as ARM_MATH_SUCCESS */
status = ARM_MATH_SUCCESS;
}
/* Return to application */
return (status);
}
/**
* @} end of MatrixMult group
*/