lib/main/CMSIS/DSP/Source/BasicMathFunctions/arm_offset_q31.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_offset_q31.c
   4  * Description:  Q31 vector offset
   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 offset
  37  * @{
  38  */
  39
  40 /**
  41  * @brief  Adds a constant offset to a Q31 vector.
  42  * @param[in]  *pSrc points to the input vector
  43  * @param[in]  offset is the offset to be added
  44  * @param[out]  *pDst points to the output vector
  45  * @param[in]  blockSize number of samples in the vector
  46  * @return none.
  47  *
  48  * <b>Scaling and Overflow Behavior:</b>
  49  * \par
  50  * The function uses saturating arithmetic.
  51  * Results outside of the allowable Q31 range [0x80000000 0x7FFFFFFF] are saturated.
  52  */
  53
  54 void arm_offset_q31(
  55   q31_t * pSrc,
  56   q31_t offset,
  57   q31_t * pDst,
  58   uint32_t blockSize)
  59 {
  60   uint32_t blkCnt;                               /* loop counter */
  61
  62 #if defined (ARM_MATH_DSP)
  63
  64 /* Run the below code for Cortex-M4 and Cortex-M3 */
  65   q31_t in1, in2, in3, in4;
  66
  67
  68   /*loop Unrolling */
  69   blkCnt = blockSize >> 2U;
  70
  71   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  72    ** a second loop below computes the remaining 1 to 3 samples. */
  73   while (blkCnt > 0U)
  74   {
  75     /* C = A + offset */
  76     /* Add offset and then store the results in the destination buffer. */
  77     in1 = *pSrc++;
  78     in2 = *pSrc++;
  79     in3 = *pSrc++;
  80     in4 = *pSrc++;
  81
  82     *pDst++ = __QADD(in1, offset);
  83     *pDst++ = __QADD(in2, offset);
  84     *pDst++ = __QADD(in3, offset);
  85     *pDst++ = __QADD(in4, offset);
  86
  87     /* Decrement the loop counter */
  88     blkCnt--;
  89   }
  90
  91   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  92    ** No loop unrolling is used. */
  93   blkCnt = blockSize % 0x4U;
  94
  95   while (blkCnt > 0U)
  96   {
  97     /* C = A + offset */
  98     /* Add offset and then store the result in the destination buffer. */
  99     *pDst++ = __QADD(*pSrc++, offset);
 100
 101     /* Decrement the loop counter */
 102     blkCnt--;
 103   }
 104
 105 #else
 106
 107   /* Run the below code for Cortex-M0 */
 108
 109   /* Initialize blkCnt with number of samples */
 110   blkCnt = blockSize;
 111
 112   while (blkCnt > 0U)
 113   {
 114     /* C = A + offset */
 115     /* Add offset and then store the result in the destination buffer. */
 116     *pDst++ = (q31_t) clip_q63_to_q31((q63_t) * pSrc++ + offset);
 117
 118     /* Decrement the loop counter */
 119     blkCnt--;
 120   }
 121
 122 #endif /* #if defined (ARM_MATH_DSP) */
 123
 124 }
 125
 126 /**
 127  * @} end of offset group
 128  */