lib/main/CMSIS/DSP/Source/BasicMathFunctions/arm_abs_q7.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_abs_q7.c
   4  * Description:  Q7 vector absolute value
   5  *
   6  * $Date:        27. January 2017
   7  * $Revision:    V.1.5.1
   8  *
   9  * Target Processor: Cortex-M cores
  10  * -------------------------------------------------------------------- */
  11 /*
  12  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
  13  *
  14  * SPDX-License-Identifier: Apache-2.0
  15  *
  16  * Licensed under the Apache License, Version 2.0 (the License); you may
  17  * not use this file except in compliance with the License.
  18  * You may obtain a copy of the License at
  19  *
  20  * www.apache.org/licenses/LICENSE-2.0
  21  *
  22  * Unless required by applicable law or agreed to in writing, software
  23  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
  24  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  25  * See the License for the specific language governing permissions and
  26  * limitations under the License.
  27  */
  28
  29 #include "arm_math.h"
  30
  31 /**
  32  * @ingroup groupMath
  33  */
  34
  35 /**
  36  * @addtogroup BasicAbs
  37  * @{
  38  */
  39
  40 /**
  41  * @brief Q7 vector absolute value.
  42  * @param[in]       *pSrc points to the input buffer
  43  * @param[out]      *pDst points to the output buffer
  44  * @param[in]       blockSize number of samples in each vector
  45  * @return none.
  46  *
  47  * \par Conditions for optimum performance
  48  *  Input and output buffers should be aligned by 32-bit
  49  *
  50  *
  51  * <b>Scaling and Overflow Behavior:</b>
  52  * \par
  53  * The function uses saturating arithmetic.
  54  * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.
  55  */
  56
  57 void arm_abs_q7(
  58   q7_t * pSrc,
  59   q7_t * pDst,
  60   uint32_t blockSize)
  61 {
  62   uint32_t blkCnt;                               /* loop counter */
  63   q7_t in;                                       /* Input value1 */
  64
  65 #if defined (ARM_MATH_DSP)
  66
  67   /* Run the below code for Cortex-M4 and Cortex-M3 */
  68   q31_t in1, in2, in3, in4;                      /* temporary input variables */
  69   q31_t out1, out2, out3, out4;                  /* temporary output variables */
  70
  71   /*loop Unrolling */
  72   blkCnt = blockSize >> 2U;
  73
  74   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  75    ** a second loop below computes the remaining 1 to 3 samples. */
  76   while (blkCnt > 0U)
  77   {
  78     /* C = |A| */
  79     /* Read inputs */
  80     in1 = (q31_t) * pSrc;
  81     in2 = (q31_t) * (pSrc + 1);
  82     in3 = (q31_t) * (pSrc + 2);
  83
  84     /* find absolute value */
  85     out1 = (in1 > 0) ? in1 : (q31_t)__QSUB8(0, in1);
  86
  87     /* read input */
  88     in4 = (q31_t) * (pSrc + 3);
  89
  90     /* find absolute value */
  91     out2 = (in2 > 0) ? in2 : (q31_t)__QSUB8(0, in2);
  92
  93     /* store result to destination */
  94     *pDst = (q7_t) out1;
  95
  96     /* find absolute value */
  97     out3 = (in3 > 0) ? in3 : (q31_t)__QSUB8(0, in3);
  98
  99     /* find absolute value */
 100     out4 = (in4 > 0) ? in4 : (q31_t)__QSUB8(0, in4);
 101
 102     /* store result to destination */
 103     *(pDst + 1) = (q7_t) out2;
 104
 105     /* store result to destination */
 106     *(pDst + 2) = (q7_t) out3;
 107
 108     /* store result to destination */
 109     *(pDst + 3) = (q7_t) out4;
 110
 111     /* update pointers to process next samples */
 112     pSrc += 4U;
 113     pDst += 4U;
 114
 115     /* Decrement the loop counter */
 116     blkCnt--;
 117   }
 118
 119   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 120    ** No loop unrolling is used. */
 121   blkCnt = blockSize % 0x4U;
 122 #else
 123
 124   /* Run the below code for Cortex-M0 */
 125   blkCnt = blockSize;
 126
 127 #endif /* #define ARM_MATH_CM0_FAMILY */
 128
 129   while (blkCnt > 0U)
 130   {
 131     /* C = |A| */
 132     /* Read the input */
 133     in = *pSrc++;
 134
 135     /* Store the Absolute result in the destination buffer */
 136     *pDst++ = (in > 0) ? in : ((in == (q7_t) 0x80) ? 0x7f : -in);
 137
 138     /* Decrement the loop counter */
 139     blkCnt--;
 140   }
 141 }
 142
 143 /**
 144  * @} end of BasicAbs group
 145  */