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  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.  */
  129.