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Functions

Name
void plp_conv_i32s_xpulpv2(const int32_t * pSrcA, const uint32_t srcALen, const int32_t * pSrcB, const uint32_t srcBLen, int32_t * pRes)
Convolution of 32-bit integer vectors kernel for XPULPV2 extension.

Functions Documentation

function plp_conv_i32s_xpulpv2

void plp_conv_i32s_xpulpv2(
    const int32_t * pSrcA,
    const uint32_t srcALen,
    const int32_t * pSrcB,
    const uint32_t srcBLen,
    int32_t * pRes
)

Convolution of 32-bit integer vectors kernel for XPULPV2 extension.

Parameters:

  • pSrcA points to the first input vector
  • srcALen Length of the first input vector
  • pSrcB points to the second input vector
  • srcBLen Length of the second input vector
  • pRes output result returned here

Return: none

Source code

/* =====================================================================
 * Project:      PULP DSP Library
 * Title:        plp_conv_i32_xpulpv2.c
 * Description:  32-bit integer singlecore convolution for XPULPV2
 *
 * $Date:        01. July 2019
 * $Revision:    V0
 *
 * Target Processor: PULP cores
 * ===================================================================== */
/*
 * Copyright (C) 2019 ETH Zurich and University of Bologna.
 *
 * Author: Moritz Scherer, ETH Zurich
 *
 * 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 "plp_math.h"

// Pre-condition: psrcALen >= psrcBLen, established by calling function plp_conv_i32
// Pre-condition: pRes has enough allocated memory, i.e. srcALen + srcBLen-1u
// Pre-condition: srcALen >= 2 and srcBLen >= 2, otherwise use vector dot product

void plp_conv_i32s_xpulpv2(const int32_t *pSrcA,
                           const uint32_t srcALen,
                           const int32_t *pSrcB,
                           const uint32_t srcBLen,
                           int32_t *pRes) {

    const int32_t *pIn1 = pSrcA;                 /* InputA pointer */
    const int32_t *pIn2 = pSrcB;                 /* InputB pointer */
    int32_t *pOut = pRes;                        /* Output pointer */
    const int32_t *px;                           /* Intermediate inputA pointer */
    const int32_t *py;                           /* Intermediate inputB pointer */
    const int32_t *pSrc1, *pSrc2;                /* Intermediate pointers */
    int32_t sum;                                 /* Accumulators */
    uint32_t blockSize1, blockSize2, blockSize3; /* Loop counters */
    uint32_t j, k, count, blkCnt;                /* Loop counters */

#if defined(PLP_MATH_LOOPUNROLL)
    int32_t acc0, acc1, acc2, acc3; /* Accumulators */
    int32_t x0, x1, x2, x3, c0;     /* Temporary variables to hold state and coefficient values */
#endif

    int32_t temp1, temp2, temp3, temp4, temp5, temp6, temp7, temp8;

    blockSize1 = srcBLen - 1U;
    blockSize2 = srcALen - (srcBLen - 1U);
    blockSize3 = blockSize1;

    /* --------------------------
     * Initializations of stage1
     * -------------------------*/

    /* sum = x[0] * y[0]
     * sum = x[0] * y[1] + x[1] * y[0]
     * ....
     * sum = x[0] * y[srcBlen - 1] + x[1] * y[srcBlen - 2] +...+ x[srcBLen - 1] * y[0]
     */

    /* In this stage the MAC operations are increased by 1 for every iteration.
       The count variable holds the number of MAC operations performed */
    count = 1U;

    /* Working pointer of inputA */
    px = pIn1;

    /* Working pointer of inputB */
    py = pIn2;

    /* ------------------------
     * Stage1 process
     * ----------------------*/

    /* The first stage starts here */
    while (blockSize1 > 0U) {
        /* Accumulator is made zero for every iteration */
        sum = 0;

        temp1 = *px;
        temp2 = *py;

#if defined(PLP_MATH_LOOPUNROLL)
        /* Loop unrolling: Compute 4 outputs at a time */
        k = count >> 1U;
        while (k > 0U) {
            temp3 = *(px + 1);
            temp4 = *(py - 1);

            sum = __MAC(sum, temp1, temp2);
            sum = __MAC(sum, temp3, temp4);

            temp1 = *(px + 2);
            temp2 = *(py - 2);

            px += 2;
            py -= 2;

            /* Decrement loop counter */
            k--;
        }

        /* Loop unrolling: Compute remaining outputs */
        k = count % 0x2U;

        if (k) {
            sum = __MAC(sum, temp1, temp2);
        }

#else
        /* Initialize k with number of samples */
        k = count;

        while (k > 0U) {
            /* Perform the multiply-accumulate */
            sum = __MAC(sum, *px++, *py--);

            /* Decrement loop counter */
            k--;
        }

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

        /* Store the result in the accumulator in the destination buffer. */
        *pOut++ = sum;

        /* Update the inputA and inputB pointers for next MAC calculation */
        py = pIn2 + count;
        px = pIn1;

        /* Increment MAC count */
        count++;

        /* Decrement loop counter */
        blockSize1--;
    }

    /* --------------------------
     * Initializations of stage2
     * ------------------------*/

    /* sum = x[0] * y[srcBLen-1] + x[1] * y[srcBLen-2] +...+ x[srcBLen-1] * y[0]
     * sum = x[1] * y[srcBLen-1] + x[2] * y[srcBLen-2] +...+ x[srcBLen]   * y[0]
     * ....
     * sum = x[srcALen-srcBLen-2] * y[srcBLen-1] + x[srcALen] * y[srcBLen-2] +...+ x[srcALen-1] *
     * y[0]
     */

    /* Working pointer of inputA */
    px = pIn1;

    /* Working pointer of inputB */
    pSrc2 = pIn2 + (srcBLen - 1U);
    py = pSrc2;

    /* count is index by which the pointer pIn1 to be incremented */
    count = 0U;

    /* -------------------
     * Stage2 process
     * ------------------*/

    /* Stage2 depends on srcBLen as in this stage srcBLen number of MACS are performed.
     * So, to loop unroll over blockSize2,
     * srcBLen should be greater than or equal to 4 */
    if (srcBLen >= 4U) {

#if defined(PLP_MATH_LOOPUNROLL)

        /* Loop unrolling: Compute 4 outputs at a time */
        blkCnt = blockSize2 >> 2U;

        while (blkCnt > 0U) {
            /* Set all accumulators to zero */
            acc0 = 0;
            acc1 = 0;
            acc2 = 0;
            acc3 = 0;

            /* Apply loop unrolling and compute 4 MACs simultaneously. */
            k = srcBLen >> 2U;
            /* read x[0], x[1], x[2] samples */
            x0 = *px++;
            x1 = *px++;
            x2 = *px++;

            /* First part of the processing with loop unrolling.  Compute 4 MACs at a time.
            ** a second loop below computes MACs for the remaining 1 to 3 samples. */
            do {
                /* Read y[srcBLen - 1] sample */
                c0 = *py--;
                /* Read x[3] sample */
                x3 = *(px);

                /* acc0 +=  x[0] * y[srcBLen - 1] */
                acc0 += x0 * c0;
                /* acc1 +=  x[1] * y[srcBLen - 1] */
                acc1 += x1 * c0;
                /* acc2 +=  x[2] * y[srcBLen - 1] */
                acc2 += x2 * c0;
                /* acc3 +=  x[3] * y[srcBLen - 1] */
                acc3 += x3 * c0;

                /* Read y[srcBLen - 2] sample */
                c0 = *py--;
                /* Read x[4] sample */
                x0 = *(px + 1U);

                /* acc0 +=  x[1] * y[srcBLen - 2] */
                acc0 += x1 * c0;
                /* acc1 +=  x[2] * y[srcBLen - 2] */
                acc1 += x2 * c0;
                /* acc2 +=  x[3] * y[srcBLen - 2] */
                acc2 += x3 * c0;
                /* acc3 +=  x[4] * y[srcBLen - 2] */
                acc3 += x0 * c0;

                /* Read y[srcBLen - 3] sample */
                c0 = *py--;
                /* Read x[5] sample */
                x1 = *(px + 2U);

                /* acc0 +=  x[2] * y[srcBLen - 3] */
                acc0 += x2 * c0;
                /* acc1 +=  x[3] * y[srcBLen - 2] */
                acc1 += x3 * c0;
                /* acc2 +=  x[4] * y[srcBLen - 2] */
                acc2 += x0 * c0;
                /* acc3 +=  x[5] * y[srcBLen - 2] */
                acc3 += x1 * c0;

                /* Read y[srcBLen - 4] sample */
                c0 = *py--;
                /* Read x[6] sample */
                x2 = *(px + 3U);
                px += 4U;

                /* acc0 +=  x[3] * y[srcBLen - 4] */
                acc0 += x3 * c0;
                /* acc1 +=  x[4] * y[srcBLen - 4] */
                acc1 += x0 * c0;
                /* acc2 +=  x[5] * y[srcBLen - 4] */
                acc2 += x1 * c0;
                /* acc3 +=  x[6] * y[srcBLen - 4] */
                acc3 += x2 * c0;

            } while (--k);

            /* If the srcBLen is not a multiple of 4, compute any remaining MACs here.
            ** No loop unrolling is used. */
            k = srcBLen % 0x4U;

            while (k > 0U) {
                /* Read y[srcBLen - 5] sample */
                c0 = *py--;
                /* Read x[7] sample */
                x3 = *px++;

                /* Perform the multiply-accumulate */
                /* acc0 +=  x[4] * y[srcBLen - 5] */
                acc0 += x0 * c0;
                /* acc1 +=  x[5] * y[srcBLen - 5] */
                acc1 += x1 * c0;
                /* acc2 +=  x[6] * y[srcBLen - 5] */
                acc2 += x2 * c0;
                /* acc3 +=  x[7] * y[srcBLen - 5] */
                acc3 += x3 * c0;

                /* Reuse the present samples for the next MAC */
                x0 = x1;
                x1 = x2;
                x2 = x3;

                /* Decrement the loop counter */
                k--;
            }

            /* Store the result in the accumulator in the destination buffer. */
            *pOut++ = acc0;
            *pOut++ = acc1;
            *pOut++ = acc2;
            *pOut++ = acc3;

            /* Increment the pointer pIn1 index, count by 4 */
            count += 4U;

            /* Update the inputA and inputB pointers for next MAC calculation */
            px = pIn1 + count;
            py = pSrc2;

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

        /* If the blockSize2 is not a multiple of 4, compute any remaining output samples here.
        ** No loop unrolling is used. */
        blkCnt = blockSize2 % 0x4U;

#else

        /* Initialize blkCnt with number of samples */
        blkCnt = blockSize2;

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

        while (blkCnt > 0U) {
            /* Accumulator is made zero for every iteration */
            sum = 0;

            temp1 = *px;
            temp2 = *py;

#if defined(PLP_MATH_LOOPUNROLL)
            /* Loop unrolling: Compute 4 outputs at a time */
            k = srcBLen >> 1U;
            while (k > 0U) {
                temp3 = *(px + 1);
                temp4 = *(py - 1);

                sum = __MAC(sum, temp1, temp2);
                sum = __MAC(sum, temp3, temp4);

                temp1 = *(px + 2);
                temp2 = *(py - 2);

                px += 2;
                py -= 2;

                /* Decrement loop counter */
                k--;
            }

            /* Loop unrolling: Compute remaining outputs */
            k = srcBLen % 0x2U;

            if (k) {
                sum = __MAC(sum, temp1, temp2);
            }

#else
            /* Initialize blkCnt with number of samples */
            k = srcBLen;

            while (k > 0U) {
                /* Perform the multiply-accumulate */
                sum = __MAC(sum, *px++, *py--);

                /* Decrement the loop counter */
                k--;
            }

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

            /* Store the result in the accumulator in the destination buffer. */
            *pOut++ = sum;

            /* Increment the MAC count */
            count++;

            /* Update the inputA and inputB pointers for next MAC calculation */
            px = pIn1 + count;
            py = pSrc2;

            /* Decrement the loop counter */
            blkCnt--;
        }
    } else {
        /* If the srcBLen is not a multiple of 4,
         * the blockSize2 loop cannot be unrolled by 4 */
        blkCnt = blockSize2;

        while (blkCnt > 0U) {
            /* Accumulator is made zero for every iteration */
            sum = 0;

            /* srcBLen number of MACS should be performed */
            k = srcBLen;

            while (k > 0U) {
                /* Perform the multiply-accumulate */
                sum = __MAC(sum, *px++, *py--);
                /* Decrement the loop counter */
                k--;
            }

            /* Store the result in the accumulator in the destination buffer. */
            *pOut++ = sum;

            /* Increment the MAC count */
            count++;

            /* Update the inputA and inputB pointers for next MAC calculation */
            px = pIn1 + count;
            py = pSrc2;

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

    /* --------------------------
     * Initializations of stage3
     * -------------------------*/

    /* sum += x[srcALen-srcBLen+1] * y[srcBLen-1] + x[srcALen-srcBLen+2] * y[srcBLen-2] +...+
     * x[srcALen-1] * y[1] sum += x[srcALen-srcBLen+2] * y[srcBLen-1] + x[srcALen-srcBLen+3] *
     * y[srcBLen-2] +...+ x[srcALen-1] * y[2]
     * ....
     * sum +=  x[srcALen-2] * y[srcBLen-1] + x[srcALen-1] * y[srcBLen-2]
     * sum +=  x[srcALen-1] * y[srcBLen-1]
     */

    /* In this stage the MAC operations are decreased by 1 for every iteration.
       The blockSize3 variable holds the number of MAC operations performed */

    /* Working pointer of inputA */
    pSrc1 = pIn1 + (srcALen - (srcBLen - 1U));
    px = pSrc1;

    /* Working pointer of inputB */
    pSrc2 = pIn2 + (srcBLen - 1U);
    py = pSrc2;

    /* -------------------
     * Stage3 process
     * ------------------*/
    while (blockSize3 > 0U) {
        /* Accumulator is made zero for every iteration */
        sum = 0;

#if defined(PLP_MATH_LOOPUNROLL)
        /* Loop unrolling: Compute 4 outputs at a time */
        k = blockSize3 >> 1U;

        temp1 = *px;
        temp2 = *py;

        while (k > 0U) {
            temp3 = *(px + 1);
            temp4 = *(py - 1);

            sum = __MAC(sum, temp1, temp2);
            sum = __MAC(sum, temp3, temp4);

            temp1 = *(px + 2);
            temp2 = *(py - 2);

            px += 2;
            py -= 2;

            /* Decrement loop counter */
            k--;
        }

        /* Loop unrolling: Compute remaining outputs */
        k = blockSize3 % 0x2U;

        if (k) {
            sum = __MAC(sum, temp1, temp2);
        }

#else

        /* Initialize blkCnt with number of samples */
        k = blockSize3;

        while (k > 0U) {
            /* Perform the multiply-accumulate */
            /* sum +=  x[srcALen-1] * y[srcBLen-1] */
            sum = __MAC(sum, *px++, *py--);
            /* Decrement loop counter */
            k--;
        }

#endif /* defined (PLP_MATH_LOOPUNROLL)*/

        /* Store the result in the accumulator in the destination buffer. */
        *pOut++ = sum;

        /* Update the inputA and inputB pointers for next MAC calculation */
        px = ++pSrc1;
        py = pSrc2;

        /* Decrement the loop counter */
        blockSize3--;
    }
}

Updated on 2023-03-01 at 16:16:32 +0000