tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_scale_f32.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_f32.c
   9 *
  10 * Description:  Multiplies a floating-point 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  * @defgroup scale Vector Scale
  49  *
  50  * Multiply a vector by a scalar value.  For floating-point data, the algorithm used is:
  51  *
  52  * <pre>
  53  *     pDst[n] = pSrc[n] * scale,   0 <= n < blockSize.
  54  * </pre>
  55  *
  56  * In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is represented by
  57  * a fractional multiplication <code>scaleFract</code> and an arithmetic shift <code>shift</code>.
  58  * The shift allows the gain of the scaling operation to exceed 1.0.
  59  * The algorithm used with fixed-point data is:
  60  *
  61  * <pre>
  62  *     pDst[n] = (pSrc[n] * scaleFract) << shift,   0 <= n < blockSize.
  63  * </pre>
  64  *
  65  * The overall scale factor applied to the fixed-point data is
  66  * <pre>
  67  *     scale = scaleFract * 2^shift.
  68  * </pre>
  69  *
  70  * The functions support in-place computation allowing the source and destination
  71  * pointers to reference the same memory buffer.
  72  */
  73
  74 /**
  75  * @addtogroup scale
  76  * @{
  77  */
  78
  79 /**
  80  * @brief Multiplies a floating-point vector by a scalar.
  81  * @param[in]       *pSrc points to the input vector
  82  * @param[in]       scale scale factor to be applied
  83  * @param[out]      *pDst points to the output vector
  84  * @param[in]       blockSize number of samples in the vector
  85  * @return none.
  86  */
  87
  88
  89 void arm_scale_f32(
  90   float32_t * pSrc,
  91   float32_t scale,
  92   float32_t * pDst,
  93   uint32_t blockSize)
  94 {
  95   uint32_t blkCnt;                               /* loop counter */
  96 #ifndef ARM_MATH_CM0_FAMILY
  97
  98 /* Run the below code for Cortex-M4 and Cortex-M3 */
  99   float32_t in1, in2, in3, in4;                  /* temporary variabels */
 100
 101   /*loop Unrolling */
 102   blkCnt = blockSize >> 2u;
 103
 104   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
 105    ** a second loop below computes the remaining 1 to 3 samples. */
 106   while(blkCnt > 0u)
 107   {
 108     /* C = A * scale */
 109     /* Scale the input and then store the results in the destination buffer. */
 110     /* read input samples from source */
 111     in1 = *pSrc;
 112     in2 = *(pSrc + 1);
 113
 114     /* multiply with scaling factor */
 115     in1 = in1 * scale;
 116
 117     /* read input sample from source */
 118     in3 = *(pSrc + 2);
 119
 120     /* multiply with scaling factor */
 121     in2 = in2 * scale;
 122
 123     /* read input sample from source */
 124     in4 = *(pSrc + 3);
 125
 126     /* multiply with scaling factor */
 127     in3 = in3 * scale;
 128     in4 = in4 * scale;
 129     /* store the result to destination */
 130     *pDst = in1;
 131     *(pDst + 1) = in2;
 132     *(pDst + 2) = in3;
 133     *(pDst + 3) = in4;
 134
 135     /* update pointers to process next samples */
 136     pSrc += 4u;
 137     pDst += 4u;
 138
 139     /* Decrement the loop counter */
 140     blkCnt--;
 141   }
 142
 143   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 144    ** No loop unrolling is used. */
 145   blkCnt = blockSize % 0x4u;
 146
 147 #else
 148
 149   /* Run the below code for Cortex-M0 */
 150
 151   /* Initialize blkCnt with number of samples */
 152   blkCnt = blockSize;
 153
 154 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 155
 156   while(blkCnt > 0u)
 157   {
 158     /* C = A * scale */
 159     /* Scale the input and then store the result in the destination buffer. */
 160     *pDst++ = (*pSrc++) * scale;
 161
 162     /* Decrement the loop counter */
 163     blkCnt--;
 164   }
 165 }
 166
 167 /**
 168  * @} end of scale group
 169  */