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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_float_to_q15.c    
  9. *    
  10. * Description:  Converts the elements of the floating-point vector to Q15 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.  * @addtogroup float_to_x    
  49.  * @{    
  50.  */
  51.  
  52. /**    
  53.  * @brief Converts the elements of the floating-point vector to Q15 vector.    
  54.  * @param[in]       *pSrc points to the floating-point input vector    
  55.  * @param[out]      *pDst points to the Q15 output vector  
  56.  * @param[in]       blockSize length of the input vector    
  57.  * @return none.    
  58.  *    
  59.  * \par Description:    
  60.  * \par  
  61.  * The equation used for the conversion process is:    
  62.  * <pre>    
  63.  *      pDst[n] = (q15_t)(pSrc[n] * 32768);   0 <= n < blockSize.    
  64.  * </pre>    
  65.  * \par Scaling and Overflow Behavior:    
  66.  * \par    
  67.  * The function uses saturating arithmetic.    
  68.  * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.    
  69.  * \note  
  70.  * In order to apply rounding, the library should be rebuilt with the ROUNDING macro    
  71.  * defined in the preprocessor section of project options.    
  72.  *    
  73.  */
  74.  
  75.  
  76. void arm_float_to_q15(
  77.   float32_t * pSrc,
  78.   q15_t * pDst,
  79.   uint32_t blockSize)
  80. {
  81.   float32_t *pIn = pSrc;                         /* Src pointer */
  82.   uint32_t blkCnt;                               /* loop counter */
  83.  
  84. #ifdef ARM_MATH_ROUNDING
  85.  
  86.   float32_t in;
  87.  
  88. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  89.  
  90. #ifndef ARM_MATH_CM0_FAMILY
  91.  
  92.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  93.  
  94.   /*loop Unrolling */
  95.   blkCnt = blockSize >> 2u;
  96.  
  97.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
  98.    ** a second loop below computes the remaining 1 to 3 samples. */
  99.   while(blkCnt > 0u)
  100.   {
  101.  
  102. #ifdef ARM_MATH_ROUNDING
  103.     /* C = A * 32768 */
  104.     /* convert from float to q15 and then store the results in the destination buffer */
  105.     in = *pIn++;
  106.     in = (in * 32768.0f);
  107.     in += in > 0.0f ? 0.5f : -0.5f;
  108.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  109.  
  110.     in = *pIn++;
  111.     in = (in * 32768.0f);
  112.     in += in > 0.0f ? 0.5f : -0.5f;
  113.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  114.  
  115.     in = *pIn++;
  116.     in = (in * 32768.0f);
  117.     in += in > 0.0f ? 0.5f : -0.5f;
  118.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  119.  
  120.     in = *pIn++;
  121.     in = (in * 32768.0f);
  122.     in += in > 0.0f ? 0.5f : -0.5f;
  123.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  124.  
  125. #else
  126.  
  127.     /* C = A * 32768 */
  128.     /* convert from float to q15 and then store the results in the destination buffer */
  129.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  130.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  131.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  132.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  133.  
  134. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  135.  
  136.     /* Decrement the loop counter */
  137.     blkCnt--;
  138.   }
  139.  
  140.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
  141.    ** No loop unrolling is used. */
  142.   blkCnt = blockSize % 0x4u;
  143.  
  144.   while(blkCnt > 0u)
  145.   {
  146.  
  147. #ifdef ARM_MATH_ROUNDING
  148.     /* C = A * 32768 */
  149.     /* convert from float to q15 and then store the results in the destination buffer */
  150.     in = *pIn++;
  151.     in = (in * 32768.0f);
  152.     in += in > 0.0f ? 0.5f : -0.5f;
  153.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  154.  
  155. #else
  156.  
  157.     /* C = A * 32768 */
  158.     /* convert from float to q15 and then store the results in the destination buffer */
  159.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  160.  
  161. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  162.  
  163.     /* Decrement the loop counter */
  164.     blkCnt--;
  165.   }
  166.  
  167.  
  168. #else
  169.  
  170.   /* Run the below code for Cortex-M0 */
  171.  
  172.   /* Loop over blockSize number of values */
  173.   blkCnt = blockSize;
  174.  
  175.   while(blkCnt > 0u)
  176.   {
  177.  
  178. #ifdef ARM_MATH_ROUNDING
  179.     /* C = A * 32768 */
  180.     /* convert from float to q15 and then store the results in the destination buffer */
  181.     in = *pIn++;
  182.     in = (in * 32768.0f);
  183.     in += in > 0 ? 0.5f : -0.5f;
  184.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  185.  
  186. #else
  187.  
  188.     /* C = A * 32768 */
  189.     /* convert from float to q15 and then store the results in the destination buffer */
  190.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  191.  
  192. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  193.  
  194.     /* Decrement the loop counter */
  195.     blkCnt--;
  196.   }
  197.  
  198. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  199.  
  200. }
  201.  
  202. /**    
  203.  * @} end of float_to_x group    
  204.  */
  205.