text: /* ----------------------------------------------------------------------    
  * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
  *    
  * $Date:        19. March 2015
  * $Revision: 	V.1.4.5
  *    
  * Project: 	    CMSIS DSP Library    
  * Title:	    arm_mat_mult_fast_q15.c    
  *    
  * Description:	 Q15 matrix multiplication (fast variant)    
  *    
  * Target Processor: Cortex-M4/Cortex-M3
  *  
  * Redistribution and use in source and binary forms, with or without 
  * modification, are permitted provided that the following conditions
  * are met:
  *   - Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  *   - Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in
  *     the documentation and/or other materials provided with the 
  *     distribution.
  *   - Neither the name of ARM LIMITED nor the names of its contributors
  *     may be used to endorse or promote products derived from this
  *     software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.    
  * -------------------------------------------------------------------- */
  
  #include "../../../../../drivers/CMSIS/Include/arm_math.h"
  
  /**    
   * @ingroup groupMatrix    
   */
  
  /**    
   * @addtogroup MatrixMult    
   * @{    
   */
  
  
  /**    
   * @brief Q15 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    
   * @param[in]		*pState points to the array for storing intermediate results    
   * @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_q15() and this fast variant is that    
   * the fast variant use a 32-bit rather than a 64-bit accumulator.    
   * The result of each 1.15 x 1.15 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 1.15 result.        
   *        
   * \par        
   * The fast version has the same overflow behavior as the standard version but provides        
   * less precision since it discards the low 16 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_q15()</code> for a slower implementation of this function    
   * which uses 64-bit accumulation to provide higher precision.    
   */
  
  arm_status arm_mat_mult_fast_q15(
    const arm_matrix_instance_q15 * pSrcA,
    const arm_matrix_instance_q15 * pSrcB,
    arm_matrix_instance_q15 * pDst,
    q15_t * pState)
  {
    q31_t sum;                                     /* accumulator */
    q15_t *pSrcBT = pState;                        /* input data matrix pointer for transpose */
    q15_t *pInA = pSrcA->pData;                    /* input data matrix pointer A of Q15 type */
    q15_t *pInB = pSrcB->pData;                    /* input data matrix pointer B of Q15 type */
    q15_t *px;                                     /* Temporary output data matrix pointer */
    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 */
    uint16_t numRowsB = pSrcB->numRows;            /* number of rows of input matrix A    */
    uint16_t col, i = 0u, row = numRowsB, colCnt;  /* loop counters */
    arm_status status;                             /* status of matrix multiplication */
  
  #ifndef UNALIGNED_SUPPORT_DISABLE
  
    q31_t in;                                      /* Temporary variable to hold the input value */
    q31_t inA1, inA2, inB1, inB2;
  
  #else
  
    q15_t in;                                      /* Temporary variable to hold the input value */
    q15_t inA1, inA2, inB1, inB2;
  
  #endif	/*	#ifndef UNALIGNED_SUPPORT_DISABLE	*/
  
  #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
    {
      /* Matrix transpose */
      do
      {
        /* Apply loop unrolling and exchange the columns with row elements */
        col = numColsB >> 2;
  
        /* The pointer px is set to starting address of the column being processed */
        px = pSrcBT + i;
  
        /* 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(col > 0u)
        {
  #ifndef UNALIGNED_SUPPORT_DISABLE
          /* Read two elements from the row */
          in = *__SIMD32(pInB)++;
  
          /* Unpack and store one element in the destination */
  #ifndef ARM_MATH_BIG_ENDIAN
  
          *px = (q15_t) in;
  
  #else
  
          *px = (q15_t) ((in & (q31_t) 0xffff0000) >> 16);
  
  #endif /*    #ifndef ARM_MATH_BIG_ENDIAN    */
  
          /* Update the pointer px to point to the next row of the transposed matrix */
          px += numRowsB;
  
          /* Unpack and store the second element in the destination */
  #ifndef ARM_MATH_BIG_ENDIAN
  
          *px = (q15_t) ((in & (q31_t) 0xffff0000) >> 16);
  
  #else
  
          *px = (q15_t) in;
  
  #endif /*    #ifndef ARM_MATH_BIG_ENDIAN    */
  
          /* Update the pointer px to point to the next row of the transposed matrix */
          px += numRowsB;
  
          /* Read two elements from the row */
          in = *__SIMD32(pInB)++;
  
          /* Unpack and store one element in the destination */
  #ifndef ARM_MATH_BIG_ENDIAN
  
          *px = (q15_t) in;
  
  #else
  
          *px = (q15_t) ((in & (q31_t) 0xffff0000) >> 16);
  
  #endif /*    #ifndef ARM_MATH_BIG_ENDIAN    */
  
          /* Update the pointer px to point to the next row of the transposed matrix */
          px += numRowsB;
  
          /* Unpack and store the second element in the destination */
  
  #ifndef ARM_MATH_BIG_ENDIAN
  
          *px = (q15_t) ((in & (q31_t) 0xffff0000) >> 16);
  
  #else
  
          *px = (q15_t) in;
  
  #endif /*    #ifndef ARM_MATH_BIG_ENDIAN    */
  
  #else
  
          /* Read one element from the row */
          in = *pInB++;
  
          /* Store one element in the destination */
          *px = in;
   
          /* Update the pointer px to point to the next row of the transposed matrix */
          px += numRowsB;
  
          /* Read one element from the row */
          in = *pInB++;
  
          /* Store one element in the destination */
          *px = in;
   
          /* Update the pointer px to point to the next row of the transposed matrix */
          px += numRowsB;
  
          /* Read one element from the row */
          in = *pInB++;
  
          /* Store one element in the destination */
          *px = in;
   
          /* Update the pointer px to point to the next row of the transposed matrix */
          px += numRowsB;
  
          /* Read one element from the row */
          in = *pInB++;
  
          /* Store one element in the destination */
          *px = in;
  
  #endif	/*	#ifndef UNALIGNED_SUPPORT_DISABLE	*/
          
  		/* Update the pointer px to point to the next row of the transposed matrix */
          px += numRowsB;
  
          /* Decrement the column loop counter */
          col--;
        }
  
        /* If the columns of pSrcB is not a multiple of 4, compute any remaining output samples here.        
         ** No loop unrolling is used. */
        col = numColsB % 0x4u;
  
        while(col > 0u)
        {
          /* Read and store the input element in the destination */
          *px = *pInB++;
  
          /* Update the pointer px to point to the next row of the transposed matrix */
          px += numRowsB;
  
          /* Decrement the column loop counter */
          col--;
        }
  
        i++;
  
        /* Decrement the row loop counter */
        row--;
  
      } while(row > 0u);
  
      /* Reset the variables for the usage in the following multiplication process */
      row = numRowsA;
      i = 0u;
      px = pDst->pData;
  
      /* The following loop performs the dot-product of each row in pSrcA with each column in pSrcB */
      /* row loop */
      do
      {
        /* 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 transposed pSrcB data */
        pInB = pSrcBT;
  
        /* column loop */
        do
        {
          /* Set the variable sum, that acts as accumulator, to zero */
          sum = 0;
  
          /* Apply loop unrolling and compute 2 MACs simultaneously. */
          colCnt = numColsA >> 2;
  
          /* Initiate the pointer pIn1 to point to the starting address of the column being processed */
          pInA = pSrcA->pData + i;
  
          /* 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) */
  #ifndef UNALIGNED_SUPPORT_DISABLE
  
            inA1 = *__SIMD32(pInA)++;
            inB1 = *__SIMD32(pInB)++;
            inA2 = *__SIMD32(pInA)++;
            inB2 = *__SIMD32(pInB)++;
  
            sum = __SMLAD(inA1, inB1, sum);
            sum = __SMLAD(inA2, inB2, sum);
  
  #else
  
            inA1 = *pInA++;
            inB1 = *pInB++;
            inA2 = *pInA++;
            sum += inA1 * inB1;
            inB2 = *pInB++;
  
            inA1 = *pInA++;
            inB1 = *pInB++;
            sum += inA2 * inB2;
            inA2 = *pInA++;
            inB2 = *pInB++;
  
            sum += inA1 * inB1;
            sum += inA2 * inB2;
  
  #endif	/*	#ifndef UNALIGNED_SUPPORT_DISABLE	*/
  
            /* Decrement the loop counter */
            colCnt--;
          }
  
          /* process odd column samples */
          colCnt = numColsA % 0x4u;
  
          while(colCnt > 0u)
          {
            /* c(m,n) = a(1,1)*b(1,1) + a(1,2) * b(2,1) + .... + a(m,p)*b(p,n) */
            sum += (q31_t) (*pInA++) * (*pInB++);
  
            colCnt--;
          }
  
          /* Saturate and store the result in the destination buffer */
          *px = (q15_t) (sum >> 15);
          px++;
  
          /* Decrement the column loop counter */
          col--;
  
        } while(col > 0u);
  
        i = i + numColsA;
  
        /* Decrement the 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        
   */
  