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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_q7_to_float.c
  4.  * Description:  Converts the elements of the Q7 vector to floating-point vector
  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 groupSupport
  33.  */
  34.  
  35. /**
  36.  * @defgroup q7_to_x  Convert 8-bit Integer value
  37.  */
  38.  
  39. /**
  40.  * @addtogroup q7_to_x
  41.  * @{
  42.  */
  43.  
  44. /**
  45.  * @brief Converts the elements of the Q7 vector to floating-point vector.
  46.  * @param[in]       *pSrc points to the Q7 input vector
  47.  * @param[out]      *pDst points to the floating-point output vector
  48.  * @param[in]       blockSize length of the input vector
  49.  * @return none.
  50.  *
  51.  * \par Description:
  52.  *
  53.  * The equation used for the conversion process is:
  54.  *
  55.  * <pre>
  56.  *      pDst[n] = (float32_t) pSrc[n] / 128;   0 <= n < blockSize.
  57.  * </pre>
  58.  *
  59.  */
  60.  
  61.  
  62. void arm_q7_to_float(
  63.   q7_t * pSrc,
  64.   float32_t * pDst,
  65.   uint32_t blockSize)
  66. {
  67.   q7_t *pIn = pSrc;                              /* Src pointer */
  68.   uint32_t blkCnt;                               /* loop counter */
  69.  
  70.  
  71. #if defined (ARM_MATH_DSP)
  72.  
  73.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  74.  
  75.   /*loop Unrolling */
  76.   blkCnt = blockSize >> 2U;
  77.  
  78.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  79.    ** a second loop below computes the remaining 1 to 3 samples. */
  80.   while (blkCnt > 0U)
  81.   {
  82.     /* C = (float32_t) A / 128 */
  83.     /* convert from q7 to float and then store the results in the destination buffer */
  84.     *pDst++ = ((float32_t) * pIn++ / 128.0f);
  85.     *pDst++ = ((float32_t) * pIn++ / 128.0f);
  86.     *pDst++ = ((float32_t) * pIn++ / 128.0f);
  87.     *pDst++ = ((float32_t) * pIn++ / 128.0f);
  88.  
  89.     /* Decrement the loop counter */
  90.     blkCnt--;
  91.   }
  92.  
  93.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  94.    ** No loop unrolling is used. */
  95.   blkCnt = blockSize % 0x4U;
  96.  
  97. #else
  98.  
  99.   /* Run the below code for Cortex-M0 */
  100.  
  101.   /* Loop over blockSize number of values */
  102.   blkCnt = blockSize;
  103.  
  104. #endif /* #if defined (ARM_MATH_DSP) */
  105.  
  106.   while (blkCnt > 0U)
  107.   {
  108.     /* C = (float32_t) A / 128 */
  109.     /* convert from q7 to float and then store the results in the destination buffer */
  110.     *pDst++ = ((float32_t) * pIn++ / 128.0f);
  111.  
  112.     /* Decrement the loop counter */
  113.     blkCnt--;
  114.   }
  115. }
  116.  
  117. /**
  118.  * @} end of q7_to_x group
  119.  */
  120.