tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_mult_q15.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_mult_q15.c
   9 *
  10 * Description:  Q15 vector multiplication.
  11 *
  12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  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 groupMath
  45  */
  46
  47 /**
  48  * @addtogroup BasicMult
  49  * @{
  50  */
  51
  52
  53 /**
  54  * @brief           Q15 vector multiplication
  55  * @param[in]       *pSrcA points to the first input vector
  56  * @param[in]       *pSrcB points to the second input vector
  57  * @param[out]      *pDst points to the output vector
  58  * @param[in]       blockSize number of samples in each vector
  59  * @return none.
  60  *
  61  * <b>Scaling and Overflow Behavior:</b>
  62  * \par
  63  * The function uses saturating arithmetic.
  64  * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
  65  */
  66
  67 void arm_mult_q15(
  68   q15_t * pSrcA,
  69   q15_t * pSrcB,
  70   q15_t * pDst,
  71   uint32_t blockSize)
  72 {
  73   uint32_t blkCnt;                               /* loop counters */
  74
  75 #ifndef ARM_MATH_CM0_FAMILY
  76
  77 /* Run the below code for Cortex-M4 and Cortex-M3 */
  78   q31_t inA1, inA2, inB1, inB2;                  /* temporary input variables */
  79   q15_t out1, out2, out3, out4;                  /* temporary output variables */
  80   q31_t mul1, mul2, mul3, mul4;                  /* temporary variables */
  81
  82   /* loop Unrolling */
  83   blkCnt = blockSize >> 2u;
  84
  85   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  86    ** a second loop below computes the remaining 1 to 3 samples. */
  87   while(blkCnt > 0u)
  88   {
  89     /* read two samples at a time from sourceA */
  90     inA1 = *__SIMD32(pSrcA)++;
  91     /* read two samples at a time from sourceB */
  92     inB1 = *__SIMD32(pSrcB)++;
  93     /* read two samples at a time from sourceA */
  94     inA2 = *__SIMD32(pSrcA)++;
  95     /* read two samples at a time from sourceB */
  96     inB2 = *__SIMD32(pSrcB)++;
  97
  98     /* multiply mul = sourceA * sourceB */
  99     mul1 = (q31_t) ((q15_t) (inA1 >> 16) * (q15_t) (inB1 >> 16));
 100     mul2 = (q31_t) ((q15_t) inA1 * (q15_t) inB1);
 101     mul3 = (q31_t) ((q15_t) (inA2 >> 16) * (q15_t) (inB2 >> 16));
 102     mul4 = (q31_t) ((q15_t) inA2 * (q15_t) inB2);
 103
 104     /* saturate result to 16 bit */
 105     out1 = (q15_t) __SSAT(mul1 >> 15, 16);
 106     out2 = (q15_t) __SSAT(mul2 >> 15, 16);
 107     out3 = (q15_t) __SSAT(mul3 >> 15, 16);
 108     out4 = (q15_t) __SSAT(mul4 >> 15, 16);
 109
 110     /* store the result */
 111 #ifndef ARM_MATH_BIG_ENDIAN
 112
 113     *__SIMD32(pDst)++ = __PKHBT(out2, out1, 16);
 114     *__SIMD32(pDst)++ = __PKHBT(out4, out3, 16);
 115
 116 #else
 117
 118     *__SIMD32(pDst)++ = __PKHBT(out2, out1, 16);
 119     *__SIMD32(pDst)++ = __PKHBT(out4, out3, 16);
 120
 121 #endif //      #ifndef ARM_MATH_BIG_ENDIAN
 122
 123     /* Decrement the blockSize loop counter */
 124     blkCnt--;
 125   }
 126
 127   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 128    ** No loop unrolling is used. */
 129   blkCnt = blockSize % 0x4u;
 130
 131 #else
 132
 133   /* Run the below code for Cortex-M0 */
 134
 135   /* Initialize blkCnt with number of samples */
 136   blkCnt = blockSize;
 137
 138 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 139
 140
 141   while(blkCnt > 0u)
 142   {
 143     /* C = A * B */
 144     /* Multiply the inputs and store the result in the destination buffer */
 145     *pDst++ = (q15_t) __SSAT((((q31_t) (*pSrcA++) * (*pSrcB++)) >> 15), 16);
 146
 147     /* Decrement the blockSize loop counter */
 148     blkCnt--;
 149   }
 150 }
 151
 152 /**
 153  * @} end of BasicMult group
 154  */