tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_negate_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_negate_q15.c
   9 *
  10 * Description:  Negates Q15 vectors.
  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 #include "arm_math.h"
  41
  42 /**
  43  * @ingroup groupMath
  44  */
  45
  46 /**
  47  * @addtogroup negate
  48  * @{
  49  */
  50
  51 /**
  52  * @brief  Negates the elements of a Q15 vector.
  53  * @param[in]  *pSrc points to the input vector
  54  * @param[out]  *pDst points to the output vector
  55  * @param[in]  blockSize number of samples in the vector
  56  * @return none.
  57  *
  58  * \par Conditions for optimum performance
  59  *  Input and output buffers should be aligned by 32-bit
  60  *
  61  *
  62  * <b>Scaling and Overflow Behavior:</b>
  63  * \par
  64  * The function uses saturating arithmetic.
  65  * The Q15 value -1 (0x8000) will be saturated to the maximum allowable positive value 0x7FFF.
  66  */
  67
  68 void arm_negate_q15(
  69   q15_t * pSrc,
  70   q15_t * pDst,
  71   uint32_t blockSize)
  72 {
  73   uint32_t blkCnt;                               /* loop counter */
  74   q15_t in;
  75
  76 #ifndef ARM_MATH_CM0_FAMILY
  77
  78 /* Run the below code for Cortex-M4 and Cortex-M3 */
  79
  80   q31_t in1, in2;                                /* Temporary variables */
  81
  82
  83   /*loop Unrolling */
  84   blkCnt = blockSize >> 2u;
  85
  86   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  87    ** a second loop below computes the remaining 1 to 3 samples. */
  88   while(blkCnt > 0u)
  89   {
  90     /* C = -A */
  91     /* Read two inputs at a time */
  92     in1 = _SIMD32_OFFSET(pSrc);
  93     in2 = _SIMD32_OFFSET(pSrc + 2);
  94
  95     /* negate two samples at a time */
  96     in1 = __QSUB16(0, in1);
  97
  98     /* negate two samples at a time */
  99     in2 = __QSUB16(0, in2);
 100
 101     /* store the result to destination 2 samples at a time */
 102     _SIMD32_OFFSET(pDst) = in1;
 103     /* store the result to destination 2 samples at a time */
 104     _SIMD32_OFFSET(pDst + 2) = in2;
 105
 106
 107     /* update pointers to process next samples */
 108     pSrc += 4u;
 109     pDst += 4u;
 110
 111     /* Decrement the loop counter */
 112     blkCnt--;
 113   }
 114
 115   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 116    ** No loop unrolling is used. */
 117   blkCnt = blockSize % 0x4u;
 118
 119 #else
 120
 121   /* Run the below code for Cortex-M0 */
 122
 123   /* Initialize blkCnt with number of samples */
 124   blkCnt = blockSize;
 125
 126 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 127
 128   while(blkCnt > 0u)
 129   {
 130     /* C = -A */
 131     /* Negate and then store the result in the destination buffer. */
 132     in = *pSrc++;
 133     *pDst++ = (in == (q15_t) 0x8000) ? 0x7fff : -in;
 134
 135     /* Decrement the loop counter */
 136     blkCnt--;
 137   }
 138 }
 139
 140 /**
 141  * @} end of negate group
 142  */