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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_offset_q7.c
  4.  * Description:  Q7 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 Q7 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 Q7 range [0x80 0x7F] are saturated.
  52.  */
  53.  
  54. void arm_offset_q7(
  55.   q7_t * pSrc,
  56.   q7_t offset,
  57.   q7_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 offset_packed;                           /* Offset packed to 32 bit */
  66.  
  67.  
  68.   /*loop Unrolling */
  69.   blkCnt = blockSize >> 2U;
  70.  
  71.   /* Offset is packed to 32 bit in order to use SIMD32 for addition */
  72.   offset_packed = __PACKq7(offset, offset, offset, offset);
  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 + offset */
  79.     /* Add offset and then store the results in the destination bufferfor 4 samples at a time. */
  80.     *__SIMD32(pDst)++ = __QADD8(*__SIMD32(pSrc)++, offset_packed);
  81.  
  82.     /* Decrement the loop counter */
  83.     blkCnt--;
  84.   }
  85.  
  86.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  87.    ** No loop unrolling is used. */
  88.   blkCnt = blockSize % 0x4U;
  89.  
  90.   while (blkCnt > 0U)
  91.   {
  92.     /* C = A + offset */
  93.     /* Add offset and then store the result in the destination buffer. */
  94.     *pDst++ = (q7_t) __SSAT(*pSrc++ + offset, 8);
  95.  
  96.     /* Decrement the loop counter */
  97.     blkCnt--;
  98.   }
  99.  
  100. #else
  101.  
  102.   /* Run the below code for Cortex-M0 */
  103.  
  104.   /* Initialize blkCnt with number of samples */
  105.   blkCnt = blockSize;
  106.  
  107.   while (blkCnt > 0U)
  108.   {
  109.     /* C = A + offset */
  110.     /* Add offset and then store the result in the destination buffer. */
  111.     *pDst++ = (q7_t) __SSAT((q15_t) * pSrc++ + offset, 8);
  112.  
  113.     /* Decrement the loop counter */
  114.     blkCnt--;
  115.   }
  116.  
  117. #endif /* #if defined (ARM_MATH_DSP) */
  118.  
  119. }
  120.  
  121. /**
  122.  * @} end of offset group
  123.  */
  124.