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  1. /* ----------------------------------------------------------------------------    
  2. * Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
  3. *    
  4. * $Date:        19. March 2015
  5. * $Revision:    V.1.4.5  
  6. *    
  7. * Project:          CMSIS DSP Library    
  8. * Title:                arm_q31_to_float.c    
  9. *    
  10. * Description:  Converts the elements of the Q31 vector to floating-point vector.      
  11. *    
  12. * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13. *  
  14. * Redistribution and use in source and binary forms, with or without
  15. * modification, are permitted provided that the following conditions
  16. * are met:
  17. *   - Redistributions of source code must retain the above copyright
  18. *     notice, this list of conditions and the following disclaimer.
  19. *   - Redistributions in binary form must reproduce the above copyright
  20. *     notice, this list of conditions and the following disclaimer in
  21. *     the documentation and/or other materials provided with the
  22. *     distribution.
  23. *   - Neither the name of ARM LIMITED nor the names of its contributors
  24. *     may be used to endorse or promote products derived from this
  25. *     software without specific prior written permission.
  26. *
  27. * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28. * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29. * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30. * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31. * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32. * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33. * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34. * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35. * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37. * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38. * POSSIBILITY OF SUCH DAMAGE.  
  39. * ---------------------------------------------------------------------------- */
  40.  
  41. #include "arm_math.h"
  42.  
  43. /**    
  44.  * @ingroup groupSupport    
  45.  */
  46.  
  47. /**    
  48.  * @defgroup q31_to_x  Convert 32-bit Integer value    
  49.  */
  50.  
  51. /**    
  52.  * @addtogroup q31_to_x    
  53.  * @{    
  54.  */
  55.  
  56. /**    
  57.  * @brief Converts the elements of the Q31 vector to floating-point vector.    
  58.  * @param[in]       *pSrc points to the Q31 input vector    
  59.  * @param[out]      *pDst points to the floating-point output vector  
  60.  * @param[in]       blockSize length of the input vector    
  61.  * @return none.    
  62.  *    
  63.  * \par Description:    
  64.  *    
  65.  * The equation used for the conversion process is:    
  66.  *  
  67.  * <pre>    
  68.  *      pDst[n] = (float32_t) pSrc[n] / 2147483648;   0 <= n < blockSize.    
  69.  * </pre>    
  70.  *  
  71.  */
  72.  
  73.  
  74. void arm_q31_to_float(
  75.   q31_t * pSrc,
  76.   float32_t * pDst,
  77.   uint32_t blockSize)
  78. {
  79.   q31_t *pIn = pSrc;                             /* Src pointer */
  80.   uint32_t blkCnt;                               /* loop counter */
  81.  
  82.  
  83. #ifndef ARM_MATH_CM0_FAMILY
  84.  
  85.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  86.  
  87.   /*loop Unrolling */
  88.   blkCnt = blockSize >> 2u;
  89.  
  90.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
  91.    ** a second loop below computes the remaining 1 to 3 samples. */
  92.   while(blkCnt > 0u)
  93.   {
  94.     /* C = (float32_t) A / 2147483648 */
  95.     /* convert from q31 to float and then store the results in the destination buffer */
  96.     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  97.     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  98.     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  99.     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  100.  
  101.     /* Decrement the loop counter */
  102.     blkCnt--;
  103.   }
  104.  
  105.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
  106.    ** No loop unrolling is used. */
  107.   blkCnt = blockSize % 0x4u;
  108.  
  109. #else
  110.  
  111.   /* Run the below code for Cortex-M0 */
  112.  
  113.   /* Loop over blockSize number of values */
  114.   blkCnt = blockSize;
  115.  
  116. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  117.  
  118.   while(blkCnt > 0u)
  119.   {
  120.     /* C = (float32_t) A / 2147483648 */
  121.     /* convert from q31 to float and then store the results in the destination buffer */
  122.     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  123.  
  124.     /* Decrement the loop counter */
  125.     blkCnt--;
  126.   }
  127. }
  128.  
  129. /**    
  130.  * @} end of q31_to_x group    
  131.  */
  132.