CMSIS-DSP/Source/MatrixFunctions/arm_mat_mult_f32.c

/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_mat_mult_f32.c
 * Description:  Floating-point matrix 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 groupMatrix
 */

/**
  @defgroup MatrixMult Matrix Multiplication

  Multiplies two matrices.

  \image html MatrixMultiplication.gif "Multiplication of two 3 x 3 matrices"

  Matrix multiplication is only defined if the number of columns of the
  first matrix equals the number of rows of the second matrix.
  Multiplying an <code>M x N</code> matrix with an <code>N x P</code> matrix results
  in an <code>M x P</code> matrix.
  When matrix size checking is enabled, the functions check:
   - that the inner dimensions of <code>pSrcA</code> and <code>pSrcB</code> are equal;
   - that the size of the output matrix equals the outer dimensions of <code>pSrcA</code> and <code>pSrcB</code>.
 */

/**
  @addtogroup MatrixMult
  @{
 */

/**
  @brief         Floating-point matrix multiplication.
  @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        execution status
                   - \ref ARM_MATH_SUCCESS       : Operation successful
                   - \ref ARM_MATH_SIZE_MISMATCH : Matrix size check failed
 */

arm_status arm_mat_mult_f32(
  const arm_matrix_instance_f32 * pSrcA,
  const arm_matrix_instance_f32 * pSrcB,
        arm_matrix_instance_f32 * pDst)
{
  float32_t *pIn1 = pSrcA->pData;                /* Input data matrix pointer A */
  float32_t *pIn2 = pSrcB->pData;                /* Input data matrix pointer B */
  float32_t *pInA = pSrcA->pData;                /* Input data matrix pointer A */
  float32_t *pInB = pSrcB->pData;                /* Input data matrix pointer B */
  float32_t *pOut = pDst->pData;                 /* Output data matrix pointer */
  float32_t *px;                                 /* Temporary output data matrix pointer */
  float32_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, 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 row being processed */
      px = pOut + i;

      /* For every row wise process, column loop counter is to be initiated */
      col = numColsB;

      /* For every row wise process, pIn2 pointer is set to starting address of pSrcB data */
      pIn2 = pSrcB->pData;

      /* column loop */
      do
      {
        /* Set the variable sum, that acts as accumulator, to zero */
        sum = 0.0f;

        /* Initialize pointer pIn1 to point to starting address of column being processed */
        pIn1 = pInA;

#if defined (ARM_MATH_LOOPUNROLL)

        /* Loop unrolling: Compute 4 MACs at a time. */
        colCnt = numColsA >> 2U;

        /* 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 += *pIn1++ * *pIn2;
          pIn2 += numColsB;

          sum += *pIn1++ * *pIn2;
          pIn2 += numColsB;

          sum += *pIn1++ * *pIn2;
          pIn2 += numColsB;

          sum += *pIn1++ * *pIn2;
          pIn2 += numColsB;

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

        /* Loop unrolling: Compute remaining MACs */
        colCnt = numColsA % 0x4U;

#else

        /* Initialize cntCnt with number of columns */
        colCnt = numColsA;

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

        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 += *pIn1++ * *pIn2;
          pIn2 += numColsB;

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

        /* Store result in destination buffer */
        *px++ = sum;

        /* Decrement column loop counter */
        col--;

        /* Update pointer pIn2 to point to starting address of next column */
        pIn2 = pInB + (numColsB - col);

      } while (col > 0U);

      /* Update pointer pInA to point to starting address of next row */
      i = i + numColsB;
      pInA = pInA + numColsA;

      /* Decrement 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
 */