CMSIS_5/CMSIS/NN/Source/NNSupportFunctions/arm_nn_mult_q15.c

/*
 * Copyright (C) 2010-2018 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.
 */

/* ----------------------------------------------------------------------
 * Project:      CMSIS NN Library
 * Title:        arm_nn_mult_q15.c
 * Description:  Q15 vector multiplication with variable output shifts
 *
 * $Date:        09. October 2020
 * $Revision:    V.1.0.2
 *
 * Target Processor:  Cortex-M cores
 *
 * -------------------------------------------------------------------- */

#include "arm_nnsupportfunctions.h"

/**
 * @ingroup groupSupport
 */

/**
 * @addtogroup NNBasicMath
 * @{
 */

/**
 * @brief           Q7 vector multiplication with variable output shifts
 * @param[in]       *pSrcA        pointer to the first input vector
 * @param[in]       *pSrcB        pointer to the second input vector
 * @param[out]      *pDst         pointer to the output vector
 * @param[in]       out_shift     amount of right-shift for output
 * @param[in]       blockSize     number of samples in each vector
 *
 * <b>Scaling and Overflow Behavior:</b>
 * \par
 * The function uses saturating arithmetic.
 * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
 */

void arm_nn_mult_q15(q15_t *pSrcA, q15_t *pSrcB, q15_t *pDst, const uint16_t out_shift, uint32_t blockSize)
{
    uint32_t blkCnt; /* loop counters */

#if defined(ARM_MATH_DSP)

    /* Run the below code for Cortex-M4 and Cortex-M3 */
    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 */

    /* loop Unrolling */
    blkCnt = blockSize >> 2U;

    /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
     ** a second loop below computes the remaining 1 to 3 samples. */
    while (blkCnt > 0U)
    {
        /* read two samples at a time from sourceA */
        inA1 = arm_nn_read_q15x2_ia((const q15_t **)&pSrcA);
        /* read two samples at a time from sourceB */
        inB1 = arm_nn_read_q15x2_ia((const q15_t **)&pSrcB);
        /* read two samples at a time from sourceA */
        inA2 = arm_nn_read_q15x2_ia((const q15_t **)&pSrcA);
        /* read two samples at a time from sourceB */
        inB2 = arm_nn_read_q15x2_ia((const 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((q31_t)(mul1 + NN_ROUND(out_shift)) >> out_shift, 16);
        out2 = (q15_t)__SSAT((q31_t)(mul2 + NN_ROUND(out_shift)) >> out_shift, 16);
        out3 = (q15_t)__SSAT((q31_t)(mul3 + NN_ROUND(out_shift)) >> out_shift, 16);
        out4 = (q15_t)__SSAT((q31_t)(mul4 + NN_ROUND(out_shift)) >> out_shift, 16);

        /* store the result */
#ifndef ARM_MATH_BIG_ENDIAN

        *__SIMD32(pDst)++ = __PKHBT(out2, out1, 16);
        *__SIMD32(pDst)++ = __PKHBT(out4, out3, 16);

#else

        *__SIMD32(pDst)++ = __PKHBT(out2, out1, 16);
        *__SIMD32(pDst)++ = __PKHBT(out4, out3, 16);

#endif /* #ifndef ARM_MATH_BIG_ENDIAN */

        /* Decrement the blockSize loop counter */
        blkCnt--;
    }

    /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
     ** No loop unrolling is used. */
    blkCnt = blockSize % 0x4U;

#else

    /* Run the below code for Cortex-M0 */

    /* Initialize blkCnt with number of samples */
    blkCnt = blockSize;

#endif /* #if defined (ARM_MATH_DSP) */

    while (blkCnt > 0U)
    {
        /* C = A * B */
        /* Multiply the inputs and store the result in the destination buffer */
        *pDst++ = (q15_t)__SSAT(((q31_t)((q31_t)(*pSrcA++) * (*pSrcB++) + NN_ROUND(out_shift)) >> out_shift), 16);

        /* Decrement the blockSize loop counter */
        blkCnt--;
    }
}

/**
 * @} end of NNBasicMath group
 */