arm_float_to_q15.c

/* ----------------------------------------------------------------------------    
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
*    
* $Date:        19. March 2015
* $Revision: 	V.1.4.5  
*    
* Project: 	    CMSIS DSP Library    
* Title:		arm_float_to_q15.c    
*    
* Description:	Converts the elements of the floating-point vector to Q15 vector.    
*    
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*  
* Redistribution and use in source and binary forms, with or without 
* modification, are permitted provided that the following conditions
* are met:
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the 
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.    
* ---------------------------------------------------------------------------- */

#include "arm_math.h"

/**    
 * @ingroup groupSupport    
 */

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

/**    
 * @brief Converts the elements of the floating-point vector to Q15 vector.    
 * @param[in]       *pSrc points to the floating-point input vector    
 * @param[out]      *pDst points to the Q15 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] = (q15_t)(pSrc[n] * 32768);   0 <= n < blockSize.    
 * </pre>    
 * \par Scaling and Overflow Behavior:    
 * \par    
 * The function uses saturating arithmetic.    
 * Results outside of the allowable Q15 range [0x8000 0x7FFF] 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_q15(
  float32_t * pSrc,
  q15_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_FAMILY

  /* 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 q15 and then store the results in the destination buffer */
    in = *pIn++;
    in = (in * 32768.0f);
    in += in > 0.0f ? 0.5f : -0.5f;
    *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));

    in = *pIn++;
    in = (in * 32768.0f);
    in += in > 0.0f ? 0.5f : -0.5f;
    *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));

    in = *pIn++;
    in = (in * 32768.0f);
    in += in > 0.0f ? 0.5f : -0.5f;
    *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));

    in = *pIn++;
    in = (in * 32768.0f);
    in += in > 0.0f ? 0.5f : -0.5f;
    *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));

#else

    /* C = A * 32768 */
    /* convert from float to q15 and then store the results in the destination buffer */
    *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
    *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
    *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
    *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);

#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 * 32768 */
    /* convert from float to q15 and then store the results in the destination buffer */
    in = *pIn++;
    in = (in * 32768.0f);
    in += in > 0.0f ? 0.5f : -0.5f;
    *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));

#else

    /* C = A * 32768 */
    /* convert from float to q15 and then store the results in the destination buffer */
    *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);

#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 * 32768 */
    /* convert from float to q15 and then store the results in the destination buffer */
    in = *pIn++;
    in = (in * 32768.0f);
    in += in > 0 ? 0.5f : -0.5f;
    *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));

#else

    /* C = A * 32768 */
    /* convert from float to q15 and then store the results in the destination buffer */
    *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);

#endif /*      #ifdef ARM_MATH_ROUNDING        */

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

#endif /* #ifndef ARM_MATH_CM0_FAMILY */

}

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