tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_scale_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_scale_q31.c
   9 *
  10 * Description:  Multiplies a Q31 vector by a scalar.
  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 scale
  49  * @{
  50  */
  51
  52 /**
  53  * @brief Multiplies a Q31 vector by a scalar.
  54  * @param[in]       *pSrc points to the input vector
  55  * @param[in]       scaleFract fractional portion of the scale value
  56  * @param[in]       shift number of bits to shift the result by
  57  * @param[out]      *pDst points to the output vector
  58  * @param[in]       blockSize number of samples in the vector
  59  * @return none.
  60  *
  61  * <b>Scaling and Overflow Behavior:</b>
  62  * \par
  63  * The input data <code>*pSrc</code> and <code>scaleFract</code> are in 1.31 format.
  64  * These are multiplied to yield a 2.62 intermediate result and this is shifted with saturation to 1.31 format.
  65  */
  66
  67 void arm_scale_q31(
  68   q31_t * pSrc,
  69   q31_t scaleFract,
  70   int8_t shift,
  71   q31_t * pDst,
  72   uint32_t blockSize)
  73 {
  74   int8_t kShift = shift + 1;                     /* Shift to apply after scaling */
  75   int8_t sign = (kShift & 0x80);
  76   uint32_t blkCnt;                               /* loop counter */
  77   q31_t in, out;
  78
  79 #ifndef ARM_MATH_CM0_FAMILY
  80
  81 /* Run the below code for Cortex-M4 and Cortex-M3 */
  82
  83   q31_t in1, in2, in3, in4;                      /* temporary input variables */
  84   q31_t out1, out2, out3, out4;                  /* temporary output variabels */
  85
  86
  87   /*loop Unrolling */
  88   blkCnt = blockSize >> 2u;
  89
  90   if(sign == 0u)
  91   {
  92     /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  93      ** a second loop below computes the remaining 1 to 3 samples. */
  94     while(blkCnt > 0u)
  95     {
  96       /* read four inputs from source */
  97       in1 = *pSrc;
  98       in2 = *(pSrc + 1);
  99       in3 = *(pSrc + 2);
 100       in4 = *(pSrc + 3);
 101
 102       /* multiply input with scaler value */
 103       in1 = ((q63_t) in1 * scaleFract) >> 32;
 104       in2 = ((q63_t) in2 * scaleFract) >> 32;
 105       in3 = ((q63_t) in3 * scaleFract) >> 32;
 106       in4 = ((q63_t) in4 * scaleFract) >> 32;
 107
 108       /* apply shifting */
 109       out1 = in1 << kShift;
 110       out2 = in2 << kShift;
 111
 112       /* saturate the results. */
 113       if(in1 != (out1 >> kShift))
 114         out1 = 0x7FFFFFFF ^ (in1 >> 31);
 115
 116       if(in2 != (out2 >> kShift))
 117         out2 = 0x7FFFFFFF ^ (in2 >> 31);
 118
 119       out3 = in3 << kShift;
 120       out4 = in4 << kShift;
 121
 122       *pDst = out1;
 123       *(pDst + 1) = out2;
 124
 125       if(in3 != (out3 >> kShift))
 126         out3 = 0x7FFFFFFF ^ (in3 >> 31);
 127
 128       if(in4 != (out4 >> kShift))
 129         out4 = 0x7FFFFFFF ^ (in4 >> 31);
 130
 131       /* Store result destination */
 132       *(pDst + 2) = out3;
 133       *(pDst + 3) = out4;
 134
 135       /* Update pointers to process next sampels */
 136       pSrc += 4u;
 137       pDst += 4u;
 138
 139       /* Decrement the loop counter */
 140       blkCnt--;
 141     }
 142
 143   }
 144   else
 145   {
 146     /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
 147      ** a second loop below computes the remaining 1 to 3 samples. */
 148     while(blkCnt > 0u)
 149     {
 150       /* read four inputs from source */
 151       in1 = *pSrc;
 152       in2 = *(pSrc + 1);
 153       in3 = *(pSrc + 2);
 154       in4 = *(pSrc + 3);
 155
 156       /* multiply input with scaler value */
 157       in1 = ((q63_t) in1 * scaleFract) >> 32;
 158       in2 = ((q63_t) in2 * scaleFract) >> 32;
 159       in3 = ((q63_t) in3 * scaleFract) >> 32;
 160       in4 = ((q63_t) in4 * scaleFract) >> 32;
 161
 162       /* apply shifting */
 163       out1 = in1 >> -kShift;
 164       out2 = in2 >> -kShift;
 165
 166       out3 = in3 >> -kShift;
 167       out4 = in4 >> -kShift;
 168
 169       /* Store result destination */
 170       *pDst = out1;
 171       *(pDst + 1) = out2;
 172
 173       *(pDst + 2) = out3;
 174       *(pDst + 3) = out4;
 175
 176       /* Update pointers to process next sampels */
 177       pSrc += 4u;
 178       pDst += 4u;
 179
 180       /* Decrement the loop counter */
 181       blkCnt--;
 182     }
 183   }
 184   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 185    ** No loop unrolling is used. */
 186   blkCnt = blockSize % 0x4u;
 187
 188 #else
 189
 190   /* Run the below code for Cortex-M0 */
 191
 192   /* Initialize blkCnt with number of samples */
 193   blkCnt = blockSize;
 194
 195 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 196
 197   if(sign == 0)
 198   {
 199           while(blkCnt > 0u)
 200           {
 201                 /* C = A * scale */
 202                 /* Scale the input and then store the result in the destination buffer. */
 203                 in = *pSrc++;
 204                 in = ((q63_t) in * scaleFract) >> 32;
 205
 206                 out = in << kShift;
 207
 208                 if(in != (out >> kShift))
 209                         out = 0x7FFFFFFF ^ (in >> 31);
 210
 211                 *pDst++ = out;
 212
 213                 /* Decrement the loop counter */
 214                 blkCnt--;
 215           }
 216   }
 217   else
 218   {
 219           while(blkCnt > 0u)
 220           {
 221                 /* C = A * scale */
 222                 /* Scale the input and then store the result in the destination buffer. */
 223                 in = *pSrc++;
 224                 in = ((q63_t) in * scaleFract) >> 32;
 225
 226                 out = in >> -kShift;
 227
 228                 *pDst++ = out;
 229
 230                 /* Decrement the loop counter */
 231                 blkCnt--;
 232           }
 233
 234   }
 235 }
 236
 237 /**
 238  * @} end of scale group
 239  */