k60-keil

来自「K60-Keil版本（下载安装MDK4.23）」· 代码 · 共 201 行

/* ----------------------------------------------------------------------------   
* Copyright (C) 2010 ARM Limited. All rights reserved.   
*   
* $Date:        15. July 2011  
* $Revision: 	V1.0.10  
*   
* Project: 	    CMSIS DSP Library   
* Title:		arm_float_to_q31.c   
*   
* Description:	Converts the elements of the floating-point vector to Q31 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"

/**   
 * @ingroup groupSupport   
 */

/**   
 * @defgroup float_to_x  Convert 32-bit floating point value   
 */

/**   
 * @addtogroup float_to_x   
 * @{   
 */

/**   
 * @brief Converts the elements of the floating-point vector to Q31 vector.   
 * @param[in]       *pSrc points to the floating-point input vector   
 * @param[out]      *pDst points to the Q31 output vector  
 * @param[in]       blockSize length of the input vector   
 * @return none.   
 *   
 *\par Description:   
 * \par  
 * The equation used for the conversion process is:   
 *  
 * <pre>   
 * 	pDst[n] = (q31_t)(pSrc[n] * 2147483648);   0 <= n < blockSize.   
 * </pre>   
 * <b>Scaling and Overflow Behavior:</b>   
 * \par   
 * The function uses saturating arithmetic.   
 * Results outside of the allowable Q31 range[0x80000000 0x7FFFFFFF] will be saturated.   
 *  
 * \note In order to apply rounding, the library should be rebuilt with the ROUNDING macro    
 * defined in the preprocessor section of project options.    
 */


void arm_float_to_q31(
  float32_t * pSrc,
  q31_t * pDst,
  uint32_t blockSize)
{
  float32_t *pIn = pSrc;                         /* Src pointer */
  uint32_t blkCnt;                               /* loop counter */

#ifdef ARM_MATH_ROUNDING

  float32_t in;

#endif /*      #ifdef ARM_MATH_ROUNDING        */

#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)
  {

#ifdef ARM_MATH_ROUNDING

    /* C = A * 32768 */
    /* convert from float to Q31 and then store the results in the destination buffer */
    in = *pIn++;
    in = (in * 2147483648.0f);
    in += in > 0 ? 0.5 : -0.5;
    *pDst++ = clip_q63_to_q31((q63_t) (in));

    in = *pIn++;
    in = (in * 2147483648.0f);
    in += in > 0 ? 0.5 : -0.5;
    *pDst++ = clip_q63_to_q31((q63_t) (in));

    in = *pIn++;
    in = (in * 2147483648.0f);
    in += in > 0 ? 0.5 : -0.5;
    *pDst++ = clip_q63_to_q31((q63_t) (in));

    in = *pIn++;
    in = (in * 2147483648.0f);
    in += in > 0 ? 0.5 : -0.5;
    *pDst++ = clip_q63_to_q31((q63_t) (in));

#else

    /* C = A * 2147483648 */
    /* convert from float to Q31 and then store the results in the destination buffer */
    *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
    *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
    *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
    *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));

#endif /*      #ifdef ARM_MATH_ROUNDING        */

    /* 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;

  while(blkCnt > 0u)
  {

#ifdef ARM_MATH_ROUNDING

    /* C = A * 2147483648 */
    /* convert from float to Q31 and then store the results in the destination buffer */
    in = *pIn++;
    in = (in * 2147483648.0f);
    in += in > 0 ? 0.5 : -0.5;
    *pDst++ = clip_q63_to_q31((q63_t) (in));

#else

    /* C = A * 2147483648 */
    /* convert from float to Q31 and then store the results in the destination buffer */
    *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));

#endif /*      #ifdef ARM_MATH_ROUNDING        */

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


#else

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

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

  while(blkCnt > 0u)
  {

#ifdef ARM_MATH_ROUNDING

    /* C = A * 2147483648 */
    /* convert from float to Q31 and then store the results in the destination buffer */
    in = *pIn++;
    in = (in * 2147483648.0f);
    in += in > 0 ? 0.5f : -0.5f;
    *pDst++ = clip_q63_to_q31((q63_t) (in));

#else

    /* C = A * 2147483648 */
    /* convert from float to Q31 and then store the results in the destination buffer */
    *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));

#endif /*      #ifdef ARM_MATH_ROUNDING        */

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

#endif /* #ifndef ARM_MATH_CM0 */

}

/**   
 * @} end of float_to_x group   
 */