tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/MatrixFunctions/arm_mat_mult_fast_q31.c

   1 /* ----------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:            arm_mat_mult_fast_q31.c
   9 *
  10 * Description:   Q31 matrix multiplication (fast variant).
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3
  13 *
  14 * Redistribution and use in source and binary forms, with or without
  15 * modification, are permitted provided that the following conditions
  16 * are met:
  17 *   - Redistributions of source code must retain the above copyright
  18 *     notice, this list of conditions and the following disclaimer.
  19 *   - Redistributions in binary form must reproduce the above copyright
  20 *     notice, this list of conditions and the following disclaimer in
  21 *     the documentation and/or other materials provided with the
  22 *     distribution.
  23 *   - Neither the name of ARM LIMITED nor the names of its contributors
  24 *     may be used to endorse or promote products derived from this
  25 *     software without specific prior written permission.
  26 *
  27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38 * POSSIBILITY OF SUCH DAMAGE.
  39 * -------------------------------------------------------------------- */
  40
  41 #include "arm_math.h"
  42
  43 /**
  44  * @ingroup groupMatrix
  45  */
  46
  47 /**
  48  * @addtogroup MatrixMult
  49  * @{
  50  */
  51
  52 /**
  53  * @brief Q31 matrix multiplication (fast variant) for Cortex-M3 and Cortex-M4
  54  * @param[in]       *pSrcA points to the first input matrix structure
  55  * @param[in]       *pSrcB points to the second input matrix structure
  56  * @param[out]      *pDst points to output matrix structure
  57  * @return              The function returns either
  58  * <code>ARM_MATH_SIZE_MISMATCH</code> or <code>ARM_MATH_SUCCESS</code> based on the outcome of size checking.
  59  *
  60  * @details
  61  * <b>Scaling and Overflow Behavior:</b>
  62  *
  63  * \par
  64  * The difference between the function arm_mat_mult_q31() and this fast variant is that
  65  * the fast variant use a 32-bit rather than a 64-bit accumulator.
  66  * The result of each 1.31 x 1.31 multiplication is truncated to
  67  * 2.30 format. These intermediate results are accumulated in a 32-bit register in 2.30
  68  * format. Finally, the accumulator is saturated and converted to a 1.31 result.
  69  *
  70  * \par
  71  * The fast version has the same overflow behavior as the standard version but provides
  72  * less precision since it discards the low 32 bits of each multiplication result.
  73  * In order to avoid overflows completely the input signals must be scaled down.
  74  * Scale down one of the input matrices by log2(numColsA) bits to
  75  * avoid overflows, as a total of numColsA additions are computed internally for each
  76  * output element.
  77  *
  78  * \par
  79  * See <code>arm_mat_mult_q31()</code> for a slower implementation of this function
  80  * which uses 64-bit accumulation to provide higher precision.
  81  */
  82
  83 arm_status arm_mat_mult_fast_q31(
  84   const arm_matrix_instance_q31 * pSrcA,
  85   const arm_matrix_instance_q31 * pSrcB,
  86   arm_matrix_instance_q31 * pDst)
  87 {
  88   q31_t *pIn1 = pSrcA->pData;                    /* input data matrix pointer A */
  89   q31_t *pIn2 = pSrcB->pData;                    /* input data matrix pointer B */
  90   q31_t *pInA = pSrcA->pData;                    /* input data matrix pointer A */
  91 //  q31_t *pSrcB = pSrcB->pData;                    /* input data matrix pointer B */
  92   q31_t *pOut = pDst->pData;                     /* output data matrix pointer */
  93   q31_t *px;                                     /* Temporary output data matrix pointer */
  94   q31_t sum;                                     /* Accumulator */
  95   uint16_t numRowsA = pSrcA->numRows;            /* number of rows of input matrix A    */
  96   uint16_t numColsB = pSrcB->numCols;            /* number of columns of input matrix B */
  97   uint16_t numColsA = pSrcA->numCols;            /* number of columns of input matrix A */
  98   uint16_t col, i = 0u, j, row = numRowsA, colCnt;      /* loop counters */
  99   arm_status status;                             /* status of matrix multiplication */
 100   q31_t inA1, inA2, inA3, inA4, inB1, inB2, inB3, inB4;
 101
 102 #ifdef ARM_MATH_MATRIX_CHECK
 103
 104
 105   /* Check for matrix mismatch condition */
 106   if((pSrcA->numCols != pSrcB->numRows) ||
 107      (pSrcA->numRows != pDst->numRows) || (pSrcB->numCols != pDst->numCols))
 108   {
 109     /* Set status as ARM_MATH_SIZE_MISMATCH */
 110     status = ARM_MATH_SIZE_MISMATCH;
 111   }
 112   else
 113 #endif /*      #ifdef ARM_MATH_MATRIX_CHECK    */
 114
 115   {
 116     /* The following loop performs the dot-product of each row in pSrcA with each column in pSrcB */
 117     /* row loop */
 118     do
 119     {
 120       /* Output pointer is set to starting address of the row being processed */
 121       px = pOut + i;
 122
 123       /* For every row wise process, the column loop counter is to be initiated */
 124       col = numColsB;
 125
 126       /* For every row wise process, the pIn2 pointer is set
 127        ** to the starting address of the pSrcB data */
 128       pIn2 = pSrcB->pData;
 129
 130       j = 0u;
 131
 132       /* column loop */
 133       do
 134       {
 135         /* Set the variable sum, that acts as accumulator, to zero */
 136         sum = 0;
 137
 138         /* Initiate the pointer pIn1 to point to the starting address of pInA */
 139         pIn1 = pInA;
 140
 141         /* Apply loop unrolling and compute 4 MACs simultaneously. */
 142         colCnt = numColsA >> 2;
 143
 144
 145         /* matrix multiplication */
 146         while(colCnt > 0u)
 147         {
 148           /* c(m,n) = a(1,1)*b(1,1) + a(1,2) * b(2,1) + .... + a(m,p)*b(p,n) */
 149           /* Perform the multiply-accumulates */
 150           inB1 = *pIn2;
 151           pIn2 += numColsB;
 152
 153           inA1 = pIn1[0];
 154           inA2 = pIn1[1];
 155
 156           inB2 = *pIn2;
 157           pIn2 += numColsB;
 158
 159           inB3 = *pIn2;
 160           pIn2 += numColsB;
 161
 162           sum = (q31_t) ((((q63_t) sum << 32) + ((q63_t) inA1 * inB1)) >> 32);
 163           sum = (q31_t) ((((q63_t) sum << 32) + ((q63_t) inA2 * inB2)) >> 32);
 164
 165           inA3 = pIn1[2];
 166           inA4 = pIn1[3];
 167
 168           inB4 = *pIn2;
 169           pIn2 += numColsB;
 170
 171           sum = (q31_t) ((((q63_t) sum << 32) + ((q63_t) inA3 * inB3)) >> 32);
 172           sum = (q31_t) ((((q63_t) sum << 32) + ((q63_t) inA4 * inB4)) >> 32);
 173
 174           pIn1 += 4u;
 175
 176           /* Decrement the loop counter */
 177           colCnt--;
 178         }
 179
 180         /* If the columns of pSrcA is not a multiple of 4, compute any remaining output samples here.
 181          ** No loop unrolling is used. */
 182         colCnt = numColsA % 0x4u;
 183
 184         while(colCnt > 0u)
 185         {
 186           /* c(m,n) = a(1,1)*b(1,1) + a(1,2) * b(2,1) + .... + a(m,p)*b(p,n) */
 187           /* Perform the multiply-accumulates */
 188           sum = (q31_t) ((((q63_t) sum << 32) +
 189                           ((q63_t) * pIn1++ * (*pIn2))) >> 32);
 190           pIn2 += numColsB;
 191
 192           /* Decrement the loop counter */
 193           colCnt--;
 194         }
 195
 196         /* Convert the result from 2.30 to 1.31 format and store in destination buffer */
 197         *px++ = sum << 1;
 198
 199         /* Update the pointer pIn2 to point to the  starting address of the next column */
 200         j++;
 201         pIn2 = pSrcB->pData + j;
 202
 203         /* Decrement the column loop counter */
 204         col--;
 205
 206       } while(col > 0u);
 207
 208       /* Update the pointer pInA to point to the  starting address of the next row */
 209       i = i + numColsB;
 210       pInA = pInA + numColsA;
 211
 212       /* Decrement the row loop counter */
 213       row--;
 214
 215     } while(row > 0u);
 216
 217     /* set status as ARM_MATH_SUCCESS */
 218     status = ARM_MATH_SUCCESS;
 219   }
 220   /* Return to application */
 221   return (status);
 222 }
 223
 224 /**
 225  * @} end of MatrixMult group
 226  */