lib/main/CMSIS/DSP/Source/SupportFunctions/arm_q15_to_float.c

   1 /* ----------------------------------------------------------------------
   2  * Project:      CMSIS DSP Library
   3  * Title:        arm_q15_to_float.c
   4  * Description:  Converts the elements of the Q15 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 q15_to_x  Convert 16-bit Integer value
  37  */
  38
  39 /**
  40  * @addtogroup q15_to_x
  41  * @{
  42  */
  43
  44
  45
  46
  47 /**
  48  * @brief  Converts the elements of the Q15 vector to floating-point vector.
  49  * @param[in]       *pSrc points to the Q15 input vector
  50  * @param[out]      *pDst points to the floating-point output vector
  51  * @param[in]       blockSize length of the input vector
  52  * @return none.
  53  *
  54  * \par Description:
  55  *
  56  * The equation used for the conversion process is:
  57  *
  58  * <pre>
  59  *      pDst[n] = (float32_t) pSrc[n] / 32768;   0 <= n < blockSize.
  60  * </pre>
  61  *
  62  */
  63
  64
  65 void arm_q15_to_float(
  66   q15_t * pSrc,
  67   float32_t * pDst,
  68   uint32_t blockSize)
  69 {
  70   q15_t *pIn = pSrc;                             /* Src pointer */
  71   uint32_t blkCnt;                               /* loop counter */
  72
  73
  74 #if defined (ARM_MATH_DSP)
  75
  76   /* Run the below code for Cortex-M4 and Cortex-M3 */
  77
  78   /*loop Unrolling */
  79   blkCnt = blockSize >> 2U;
  80
  81   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  82    ** a second loop below computes the remaining 1 to 3 samples. */
  83   while (blkCnt > 0U)
  84   {
  85     /* C = (float32_t) A / 32768 */
  86     /* convert from q15 to float and then store the results in the destination buffer */
  87     *pDst++ = ((float32_t) * pIn++ / 32768.0f);
  88     *pDst++ = ((float32_t) * pIn++ / 32768.0f);
  89     *pDst++ = ((float32_t) * pIn++ / 32768.0f);
  90     *pDst++ = ((float32_t) * pIn++ / 32768.0f);
  91
  92     /* Decrement the loop counter */
  93     blkCnt--;
  94   }
  95
  96   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  97    ** No loop unrolling is used. */
  98   blkCnt = blockSize % 0x4U;
  99
 100 #else
 101
 102   /* Run the below code for Cortex-M0 */
 103
 104   /* Loop over blockSize number of values */
 105   blkCnt = blockSize;
 106
 107 #endif /* #if defined (ARM_MATH_DSP) */
 108
 109   while (blkCnt > 0U)
 110   {
 111     /* C = (float32_t) A / 32768 */
 112     /* convert from q15 to float and then store the results in the destination buffer */
 113     *pDst++ = ((float32_t) * pIn++ / 32768.0f);
 114
 115     /* Decrement the loop counter */
 116     blkCnt--;
 117   }
 118 }
 119
 120 /**
 121  * @} end of q15_to_x group
 122  */