Subversion Repositories DashDisplay

/* ----------------------------------------------------------------------------    

* 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_q7.c    

*    

* Description:  Converts the elements of the floating-point vector to Q7 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;

* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

* 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 Q7 vector.    

 * @param[in]       *pSrc points to the floating-point input vector    

 * @param[out]      *pDst points to the Q7 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] = (q7_t)(pSrc[n] * 128);   0 <= n < blockSize.    

 * </pre>    

 * \par Scaling and Overflow Behavior:    

 * \par    

 * The function uses saturating arithmetic.    

 * Results outside of the allowable Q7 range [0x80 0x7F] 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_q7(

  float32_t * pSrc,

  q7_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 * 128 */

    /* convert from float to q7 and then store the results in the destination buffer */

    in = *pIn++;

    in = (in * 128);

    in += in > 0.0f ? 0.5f : -0.5f;

    *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));

    in = *pIn++;

    in = (in * 128);

    in += in > 0.0f ? 0.5f : -0.5f;

    *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));

    in = *pIn++;

    in = (in * 128);

    in += in > 0.0f ? 0.5f : -0.5f;

    *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));

    in = *pIn++;

    in = (in * 128);

    in += in > 0.0f ? 0.5f : -0.5f;

    *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));

#else

    /* C = A * 128 */

    /* convert from float to q7 and then store the results in the destination buffer */

    *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);

    *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);

    *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);

    *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);

#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 * 128 */

    /* convert from float to q7 and then store the results in the destination buffer */

    in = *pIn++;

    in = (in * 128);

    in += in > 0.0f ? 0.5f : -0.5f;

    *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));

#else

    /* C = A * 128 */

    /* convert from float to q7 and then store the results in the destination buffer */

    *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);

#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 * 128 */

    /* convert from float to q7 and then store the results in the destination buffer */

    in = *pIn++;

    in = (in * 128.0f);

    in += in > 0 ? 0.5f : -0.5f;

    *pDst++ = (q7_t) (__SSAT((q31_t) (in), 8));

#else

    /* C = A * 128 */

    /* convert from float to q7 and then store the results in the destination buffer */

    *pDst++ = (q7_t) __SSAT((q31_t) (*pIn++ * 128.0f), 8);

#endif /*      #ifdef ARM_MATH_ROUNDING        */

    /* Decrement the loop counter */

    blkCnt--;

  }

#endif /* #ifndef ARM_MATH_CM0_FAMILY */

}

/**    

 * @} end of float_to_x group    

 */