tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/BasicMathFunctions/arm_abs_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_abs_q7.c
   9 *
  10 * Description:  Q7 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 Q7 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  * \par Conditions for optimum performance
  60  *  Input and output buffers should be aligned by 32-bit
  61  *
  62  *
  63  * <b>Scaling and Overflow Behavior:</b>
  64  * \par
  65  * The function uses saturating arithmetic.
  66  * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.
  67  */
  68
  69 void arm_abs_q7(
  70   q7_t * pSrc,
  71   q7_t * pDst,
  72   uint32_t blockSize)
  73 {
  74   uint32_t blkCnt;                               /* loop counter */
  75   q7_t in;                                       /* Input value1 */
  76
  77 #ifndef ARM_MATH_CM0_FAMILY
  78
  79   /* Run the below code for Cortex-M4 and Cortex-M3 */
  80   q31_t in1, in2, in3, in4;                      /* temporary input variables */
  81   q31_t out1, out2, out3, out4;                  /* temporary output variables */
  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 inputs */
  92     in1 = (q31_t) * pSrc;
  93     in2 = (q31_t) * (pSrc + 1);
  94     in3 = (q31_t) * (pSrc + 2);
  95
  96     /* find absolute value */
  97     out1 = (in1 > 0) ? in1 : (q31_t)__QSUB8(0, in1);
  98
  99     /* read input */
 100     in4 = (q31_t) * (pSrc + 3);
 101
 102     /* find absolute value */
 103     out2 = (in2 > 0) ? in2 : (q31_t)__QSUB8(0, in2);
 104
 105     /* store result to destination */
 106     *pDst = (q7_t) out1;
 107
 108     /* find absolute value */
 109     out3 = (in3 > 0) ? in3 : (q31_t)__QSUB8(0, in3);
 110
 111     /* find absolute value */
 112     out4 = (in4 > 0) ? in4 : (q31_t)__QSUB8(0, in4);
 113
 114     /* store result to destination */
 115     *(pDst + 1) = (q7_t) out2;
 116
 117     /* store result to destination */
 118     *(pDst + 2) = (q7_t) out3;
 119
 120     /* store result to destination */
 121     *(pDst + 3) = (q7_t) out4;
 122
 123     /* update pointers to process next samples */
 124     pSrc += 4u;
 125     pDst += 4u;
 126
 127     /* Decrement the loop counter */
 128     blkCnt--;
 129   }
 130
 131   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 132    ** No loop unrolling is used. */
 133   blkCnt = blockSize % 0x4u;
 134 #else
 135
 136   /* Run the below code for Cortex-M0 */
 137   blkCnt = blockSize;
 138
 139 #endif //      #define ARM_MATH_CM0_FAMILY
 140
 141   while(blkCnt > 0u)
 142   {
 143     /* C = |A| */
 144     /* Read the input */
 145     in = *pSrc++;
 146
 147     /* Store the Absolute result in the destination buffer */
 148     *pDst++ = (in > 0) ? in : ((in == (q7_t) 0x80) ? 0x7f : -in);
 149
 150     /* Decrement the loop counter */
 151     blkCnt--;
 152   }
 153 }
 154
 155 /**
 156  * @} end of BasicAbs group
 157  */