tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_abs_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_abs_q15.c
   9 *
  10 * Description:  Q15 vector absolute value.
  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 BasicAbs
  49  * @{
  50  */
  51
  52 /**
  53  * @brief Q15 vector absolute value.
  54  * @param[in]       *pSrc points to the input buffer
  55  * @param[out]      *pDst points to the output buffer
  56  * @param[in]       blockSize number of samples in each vector
  57  * @return none.
  58  *
  59  * <b>Scaling and Overflow Behavior:</b>
  60  * \par
  61  * The function uses saturating arithmetic.
  62  * The Q15 value -1 (0x8000) will be saturated to the maximum allowable positive value 0x7FFF.
  63  */
  64
  65 void arm_abs_q15(
  66   q15_t * pSrc,
  67   q15_t * pDst,
  68   uint32_t blockSize)
  69 {
  70   uint32_t blkCnt;                               /* loop counter */
  71
  72 #ifndef ARM_MATH_CM0_FAMILY
  73   __SIMD32_TYPE *simd;
  74
  75 /* Run the below code for Cortex-M4 and Cortex-M3 */
  76
  77   q15_t in1;                                     /* Input value1 */
  78   q15_t in2;                                     /* Input value2 */
  79
  80
  81   /*loop Unrolling */
  82   blkCnt = blockSize >> 2u;
  83
  84   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  85    ** a second loop below computes the remaining 1 to 3 samples. */
  86   simd = __SIMD32_CONST(pDst);
  87   while(blkCnt > 0u)
  88   {
  89     /* C = |A| */
  90     /* Read two inputs */
  91     in1 = *pSrc++;
  92     in2 = *pSrc++;
  93
  94
  95     /* Store the Absolute result in the destination buffer by packing the two values, in a single cycle */
  96 #ifndef  ARM_MATH_BIG_ENDIAN
  97     *simd++ =
  98       __PKHBT(((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)),
  99               ((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)), 16);
 100
 101 #else
 102
 103
 104     *simd++ =
 105       __PKHBT(((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)),
 106               ((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)), 16);
 107
 108 #endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */
 109
 110     in1 = *pSrc++;
 111     in2 = *pSrc++;
 112
 113
 114 #ifndef  ARM_MATH_BIG_ENDIAN
 115
 116     *simd++ =
 117       __PKHBT(((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)),
 118               ((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)), 16);
 119
 120 #else
 121
 122
 123     *simd++ =
 124       __PKHBT(((in2 > 0) ? in2 : (q15_t)__QSUB16(0, in2)),
 125               ((in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1)), 16);
 126
 127 #endif /* #ifndef  ARM_MATH_BIG_ENDIAN    */
 128
 129     /* Decrement the loop counter */
 130     blkCnt--;
 131   }
 132   pDst = (q15_t *)simd;
 133
 134   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 135    ** No loop unrolling is used. */
 136   blkCnt = blockSize % 0x4u;
 137
 138   while(blkCnt > 0u)
 139   {
 140     /* C = |A| */
 141     /* Read the input */
 142     in1 = *pSrc++;
 143
 144     /* Calculate absolute value of input and then store the result in the destination buffer. */
 145     *pDst++ = (in1 > 0) ? in1 : (q15_t)__QSUB16(0, in1);
 146
 147     /* Decrement the loop counter */
 148     blkCnt--;
 149   }
 150
 151 #else
 152
 153   /* Run the below code for Cortex-M0 */
 154
 155   q15_t in;                                      /* Temporary input variable */
 156
 157   /* Initialize blkCnt with number of samples */
 158   blkCnt = blockSize;
 159
 160   while(blkCnt > 0u)
 161   {
 162     /* C = |A| */
 163     /* Read the input */
 164     in = *pSrc++;
 165
 166     /* Calculate absolute value of input and then store the result in the destination buffer. */
 167     *pDst++ = (in > 0) ? in : ((in == (q15_t) 0x8000) ? 0x7fff : -in);
 168
 169     /* Decrement the loop counter */
 170     blkCnt--;
 171   }
 172
 173 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 174
 175 }
 176
 177 /**
 178  * @} end of BasicAbs group
 179  */