tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_negate_q7.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_q7.c
   9 *
  10 * Description:  Negates Q7 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
  41 #include "arm_math.h"
  42
  43 /**
  44  * @ingroup groupMath
  45  */
  46
  47 /**
  48  * @addtogroup negate
  49  * @{
  50  */
  51
  52 /**
  53  * @brief  Negates the elements of a Q7 vector.
  54  * @param[in]  *pSrc points to the input vector
  55  * @param[out]  *pDst points to the output vector
  56  * @param[in]  blockSize number of samples in the vector
  57  * @return none.
  58  *
  59  * <b>Scaling and Overflow Behavior:</b>
  60  * \par
  61  * The function uses saturating arithmetic.
  62  * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.
  63  */
  64
  65 void arm_negate_q7(
  66   q7_t * pSrc,
  67   q7_t * pDst,
  68   uint32_t blockSize)
  69 {
  70   uint32_t blkCnt;                               /* loop counter */
  71   q7_t in;
  72
  73 #ifndef ARM_MATH_CM0_FAMILY
  74
  75 /* Run the below code for Cortex-M4 and Cortex-M3 */
  76   q31_t input;                                   /* Input values1-4 */
  77   q31_t zero = 0x00000000;
  78
  79
  80   /*loop Unrolling */
  81   blkCnt = blockSize >> 2u;
  82
  83   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  84    ** a second loop below computes the remaining 1 to 3 samples. */
  85   while(blkCnt > 0u)
  86   {
  87     /* C = -A */
  88     /* Read four inputs */
  89     input = *__SIMD32(pSrc)++;
  90
  91     /* Store the Negated results in the destination buffer in a single cycle by packing the results */
  92     *__SIMD32(pDst)++ = __QSUB8(zero, input);
  93
  94     /* Decrement the loop counter */
  95     blkCnt--;
  96   }
  97
  98   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  99    ** No loop unrolling is used. */
 100   blkCnt = blockSize % 0x4u;
 101
 102 #else
 103
 104   /* Run the below code for Cortex-M0 */
 105
 106   /* Initialize blkCnt with number of samples */
 107   blkCnt = blockSize;
 108
 109 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 110
 111   while(blkCnt > 0u)
 112   {
 113     /* C = -A */
 114     /* Negate and then store the results in the destination buffer. */ \
 115       in = *pSrc++;
 116     *pDst++ = (in == (q7_t) 0x80) ? 0x7f : -in;
 117
 118     /* Decrement the loop counter */
 119     blkCnt--;
 120   }
 121 }
 122
 123 /**
 124  * @} end of negate group
 125  */