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/* ----------------------------------------------------------------------

 * Project:      CMSIS DSP Library

 * Title:        arm_mat_mult_fast_q31.c

 * Description:  Q31 matrix multiplication (fast variant)

 *

 * $Date:        27. January 2017

 * $Revision:    V.1.5.1

 *

 * Target Processor: Cortex-M cores

 * -------------------------------------------------------------------- */

/*

 * Copyright (C) 2010-2017 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 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

 * <code>ARM_MATH_SIZE_MISMATCH</code> or <code>ARM_MATH_SUCCESS</code> based on the outcome of size checking.

 *

 * @details

 * <b>Scaling and Overflow Behavior:</b>

 *

 * \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 <code>arm_mat_mult_q31()</code> 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 *pInA = pSrcA->pData;                    /* input data matrix pointer A */

  q31_t *pInB = pSrcB->pData;                    /* input data matrix pointer B */

  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 */

  uint32_t col, i = 0U, j, row = numRowsA, colCnt;  /* loop counters */

  arm_status status;                             /* status of matrix multiplication */

  q31_t inA1, inB1;

#if defined (ARM_MATH_DSP)

  q31_t sum2, sum3, sum4;

  q31_t inA2, inB2;

  q31_t *pInA2;

  q31_t *px2;

#endif

#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    */

  {

    px = pDst->pData;

#if defined (ARM_MATH_DSP)

    row = row >> 1;

    px2 = px + numColsB;

#endif

    /* The following loop performs the dot-product of each row in pSrcA with each column in pSrcB */

    /* row loop */

    while (row > 0U)

    {

      /* 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 */

      pInB = pSrcB->pData;

      j = 0U;

#if defined (ARM_MATH_DSP)

      col = col >> 1;

#endif

      /* column loop */

      while (col > 0U)

      {

        /* Set the variable sum, that acts as accumulator, to zero */

        sum = 0;

        /* Initiate data pointers */

        pInA = pSrcA->pData + i;

        pInB  = pSrcB->pData + j;

#if defined (ARM_MATH_DSP)

        sum2 = 0;

        sum3 = 0;

        sum4 = 0;

        pInA2 = pInA + numColsA;

        colCnt = numColsA;

#else

        colCnt = numColsA >> 2;

#endif

        /* matrix multiplication */

        while (colCnt > 0U)

        {

#if defined (ARM_MATH_DSP)

          inA1 = *pInA++;

          inB1 = pInB[0];

          inA2 = *pInA2++;

          inB2 = pInB[1];

          pInB += numColsB;

          sum  = __SMMLA(inA1, inB1, sum);

          sum2 = __SMMLA(inA1, inB2, sum2);

          sum3 = __SMMLA(inA2, inB1, sum3);

          sum4 = __SMMLA(inA2, inB2, sum4);

#else

          /* 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 */

          inB1 = *pInB;

          pInB += numColsB;

          inA1 = pInA[0];

          sum = __SMMLA(inA1, inB1, sum);

          inB1 = *pInB;

          pInB += numColsB;

          inA1 = pInA[1];

          sum = __SMMLA(inA1, inB1, sum);

          inB1 = *pInB;

          pInB += numColsB;

          inA1 = pInA[2];

          sum = __SMMLA(inA1, inB1, sum);

          inB1 = *pInB;

          pInB += numColsB;

          inA1 = pInA[3];

          sum = __SMMLA(inA1, inB1, sum);

          pInA += 4U;

#endif

          /* Decrement the loop counter */

          colCnt--;

        }

#ifdef ARM_MATH_CM0_FAMILY

        /* If the columns of pSrcA is not a multiple of 4, compute any remaining output samples here. */

        colCnt = numColsA % 0x4U;

        while (colCnt > 0U)

        {

          sum = __SMMLA(*pInA++, *pInB, sum);

          pInB += numColsB;

          colCnt--;

        }

        j++;

#endif

        /* Convert the result from 2.30 to 1.31 format and store in destination buffer */

        *px++  = sum << 1;

#if defined (ARM_MATH_DSP)

        *px++  = sum2 << 1;

        *px2++ = sum3 << 1;

        *px2++ = sum4 << 1;

        j += 2;

#endif

        /* Decrement the column loop counter */

        col--;

      }

      i = i + numColsA;

#if defined (ARM_MATH_DSP)

      i = i + numColsA;

      px = px2 + (numColsB & 1U);

      px2 = px + numColsB;

#endif

      /* Decrement the row loop counter */

      row--;

    }

    /* Compute any remaining odd row/column below */

#if defined (ARM_MATH_DSP)

    /* Compute remaining output column */

    if (numColsB & 1U) {

      /* Avoid redundant computation of last element */

      row = numRowsA & (~0x1);

      /* Point to remaining unfilled column in output matrix */

      px = pDst->pData+numColsB-1;

      pInA = pSrcA->pData;

      /* row loop */

      while (row > 0)

      {

        /* point to last column in matrix B */

        pInB  = pSrcB->pData + numColsB-1;

        /* Set the variable sum, that acts as accumulator, to zero */

        sum  = 0;

        /* Compute 4 columns at once */

        colCnt = numColsA >> 2;

        /* matrix multiplication */

        while (colCnt > 0U)

        {

          inA1 = *pInA++;

          inA2 = *pInA++;

          inB1 = *pInB;

          pInB += numColsB;

          inB2 = *pInB;

          pInB += numColsB;

          sum = __SMMLA(inA1, inB1, sum);

          sum = __SMMLA(inA2, inB2, sum);

          inA1 = *pInA++;

          inA2 = *pInA++;

          inB1 = *pInB;

          pInB += numColsB;

          inB2 = *pInB;

          pInB += numColsB;

          sum = __SMMLA(inA1, inB1, sum);

          sum = __SMMLA(inA2, inB2, sum);

          /* Decrement the loop counter */

          colCnt--;

        }

        colCnt = numColsA & 3U;

        while (colCnt > 0U) {

          sum = __SMMLA(*pInA++, *pInB, sum);

          pInB += numColsB;

          colCnt--;

        }

        /* Convert the result from 2.30 to 1.31 format and store in destination buffer */

        *px = sum << 1;

        px += numColsB;

        /* Decrement the row loop counter */

        row--;

      }

    }

    /* Compute remaining output row */

    if (numRowsA & 1U) {

      /* point to last row in output matrix */

      px = pDst->pData+(numColsB)*(numRowsA-1);

      col = numColsB;

      i = 0U;

      /* col loop */

      while (col > 0)

      {

        /* point to last row in matrix A */

        pInA = pSrcA->pData + (numRowsA-1)*numColsA;

        pInB  = pSrcB->pData + i;

        /* Set the variable sum, that acts as accumulator, to zero */

        sum  = 0;

        /* Compute 4 columns at once */

        colCnt = numColsA >> 2;

        /* matrix multiplication */

        while (colCnt > 0U)

        {

          inA1 = *pInA++;

          inA2 = *pInA++;

          inB1 = *pInB;

          pInB += numColsB;

          inB2 = *pInB;

          pInB += numColsB;

          sum = __SMMLA(inA1, inB1, sum);

          sum = __SMMLA(inA2, inB2, sum);

          inA1 = *pInA++;

          inA2 = *pInA++;

          inB1 = *pInB;

          pInB += numColsB;

          inB2 = *pInB;

          pInB += numColsB;

          sum = __SMMLA(inA1, inB1, sum);

          sum = __SMMLA(inA2, inB2, sum);

          /* Decrement the loop counter */

          colCnt--;

        }

        colCnt = numColsA & 3U;

        while (colCnt > 0U) {

          sum = __SMMLA(*pInA++, *pInB, sum);

          pInB += numColsB;

          colCnt--;

        }

        /* Saturate and store the result in the destination buffer */

        *px++ = sum << 1;

        i++;

        /* Decrement the col loop counter */

        col--;

      }

    }

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

    /* set status as ARM_MATH_SUCCESS */

    status = ARM_MATH_SUCCESS;

  }

  /* Return to application */

  return (status);

}

/**

 * @} end of MatrixMult group

 */