/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_mult_q15.c
* Description: Q15 vector multiplication
*
* $Date: 18. March 2019
* $Revision: V1.6.0
*
* Target Processor: Cortex-M cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "arm_math.h"
/**
@ingroup groupMath
*/
/**
@addtogroup BasicMult
@{
*/
/**
@brief Q15 vector multiplication
@param[in] pSrcA points to first input vector
@param[in] pSrcB points to second input vector
@param[out] pDst points to output vector
@param[in] blockSize number of samples in each vector
@return none
@par Scaling and Overflow Behavior
The function uses saturating arithmetic.
Results outside of the allowable Q15 range [0x8000 0x7FFF] are saturated.
*/
void arm_mult_q15(
const q15_t * pSrcA,
const q15_t * pSrcB,
q15_t * pDst,
uint32_t blockSize)
{
uint32_t blkCnt; /* Loop counter */
#if defined (ARM_MATH_LOOPUNROLL)
#if defined (ARM_MATH_DSP)
q31_t inA1, inA2, inB1, inB2; /* Temporary input variables */
q15_t out1, out2, out3, out4; /* Temporary output variables */
q31_t mul1, mul2, mul3, mul4; /* Temporary variables */
#endif
/* Loop unrolling: Compute 4 outputs at a time */
blkCnt = blockSize >> 2U;
while (blkCnt > 0U)
{
/* C = A * B */
#if defined (ARM_MATH_DSP)
/* read 2 samples at a time from sourceA */
inA1 = read_q15x2_ia ((q15_t **) &pSrcA);
/* read 2 samples at a time from sourceB */
inB1 = read_q15x2_ia ((q15_t **) &pSrcB);
/* read 2 samples at a time from sourceA */
inA2 = read_q15x2_ia ((q15_t **) &pSrcA);
/* read 2 samples at a time from sourceB */
inB2 = read_q15x2_ia ((q15_t **) &pSrcB);
/* multiply mul = sourceA * sourceB */
mul1 = (q31_t) ((q15_t) (inA1 >> 16) * (q15_t) (inB1 >> 16));
mul2 = (q31_t) ((q15_t) (inA1 ) * (q15_t) (inB1 ));
mul3 = (q31_t) ((q15_t) (inA2 >> 16) * (q15_t) (inB2 >> 16));
mul4 = (q31_t) ((q15_t) (inA2 ) * (q15_t) (inB2 ));
/* saturate result to 16 bit */
out1 = (q15_t) __SSAT(mul1 >> 15, 16);
out2 = (q15_t) __SSAT(mul2 >> 15, 16);
out3 = (q15_t) __SSAT(mul3 >> 15, 16);
out4 = (q15_t) __SSAT(mul4 >> 15, 16);
/* store result to destination */
#ifndef ARM_MATH_BIG_ENDIAN
write_q15x2_ia (&pDst, __PKHBT(out2, out1, 16));
write_q15x2_ia (&pDst, __PKHBT(out4, out3, 16));
#else
write_q15x2_ia (&pDst, __PKHBT(out1, out2, 16));
write_q15x2_ia (&pDst, __PKHBT(out3, out4, 16));
#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
#else
*pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
*pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
*pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
*pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
#endif
/* Decrement loop counter */
blkCnt--;
}
/* Loop unrolling: Compute remaining outputs */
blkCnt = blockSize % 0x4U;
#else
/* Initialize blkCnt with number of samples */
blkCnt = blockSize;
#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
while (blkCnt > 0U)
{
/* C = A * B */
/* Multiply inputs and store result in destination buffer. */
*pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
/* Decrement loop counter */
blkCnt--;
}
}
/**
@} end of BasicMult group
*/
