lib/main/CMSIS/DSP/Source/SupportFunctions/arm_q31_to_float.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_q31_to_float.c
   4  * Description:  Converts the elements of the Q31 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 q31_to_x  Convert 32-bit Integer value
  37  */
  38
  39 /**
  40  * @addtogroup q31_to_x
  41  * @{
  42  */
  43
  44 /**
  45  * @brief Converts the elements of the Q31 vector to floating-point vector.
  46  * @param[in]       *pSrc points to the Q31 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] / 2147483648;   0 <= n < blockSize.
  57  * </pre>
  58  *
  59  */
  60
  61
  62 void arm_q31_to_float(
  63   q31_t * pSrc,
  64   float32_t * pDst,
  65   uint32_t blockSize)
  66 {
  67   q31_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 / 2147483648 */
  83     /* convert from q31 to float and then store the results in the destination buffer */
  84     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  85     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  86     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  87     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  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 / 2147483648 */
 109     /* convert from q31 to float and then store the results in the destination buffer */
 110     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
 111
 112     /* Decrement the loop counter */
 113     blkCnt--;
 114   }
 115 }
 116
 117 /**
 118  * @} end of q31_to_x group
 119  */