arm_q31_to_float.c

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/* ----------------------------------------------------------------------------   
* Copyright (C) 2010 ARM Limited. All rights reserved.   
*   
* $Date:        15. July 2011  
* $Revision:    V1.0.10  
*   
* Project:      CMSIS DSP Library   
* Title:        arm_q31_to_float.c   
*   
* Description:  Converts the elements of the Q31 vector to floating-point vector.     
*   
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*  
* Version 1.0.10 2011/7/15 
*    Big Endian support added and Merged M0 and M3/M4 Source code.  
*   
* Version 1.0.3 2010/11/29  
*    Re-organized the CMSIS folders and updated documentation.   
*    
* Version 1.0.2 2010/11/11   
*    Documentation updated.    
*   
* Version 1.0.1 2010/10/05    
*    Production release and review comments incorporated.   
*   
* Version 1.0.0 2010/09/20    
*    Production release and review comments incorporated.   
* ---------------------------------------------------------------------------- */

#include "arm_math.h"

void arm_q31_to_float(
  q31_t * pSrc,
  float32_t * pDst,
  uint32_t blockSize)
{
  q31_t *pIn = pSrc;                             /* Src pointer */
  uint32_t blkCnt;                               /* loop counter */


#ifndef ARM_MATH_CM0

  /* Run the below code for Cortex-M4 and Cortex-M3 */

  /*loop Unrolling */
  blkCnt = blockSize >> 2u;

  /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.   
   ** a second loop below computes the remaining 1 to 3 samples. */
  while(blkCnt > 0u)
  {
    /* C = (float32_t) A / 2147483648 */
    /* convert from q31 to float and then store the results in the destination buffer */
    *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
    *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
    *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
    *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);

    /* Decrement the loop counter */
    blkCnt--;
  }

  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.   
   ** No loop unrolling is used. */
  blkCnt = blockSize % 0x4u;

#else

  /* Run the below code for Cortex-M0 */

  /* Loop over blockSize number of values */
  blkCnt = blockSize;

#endif /* #ifndef ARM_MATH_CM0 */

  while(blkCnt > 0u)
  {
    /* C = (float32_t) A / 2147483648 */
    /* convert from q31 to float and then store the results in the destination buffer */
    *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);

    /* Decrement the loop counter */
    blkCnt--;
  }
}