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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_q31.c    
  9. *    
  10. * Description:  Converts the elements of the floating-point vector to Q31 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 float_to_x  Convert 32-bit floating point value    
  49.  */
  50.  
  51. /**    
  52.  * @addtogroup float_to_x    
  53.  * @{    
  54.  */
  55.  
  56. /**    
  57.  * @brief Converts the elements of the floating-point vector to Q31 vector.    
  58.  * @param[in]       *pSrc points to the floating-point input vector    
  59.  * @param[out]      *pDst points to the Q31 output vector  
  60.  * @param[in]       blockSize length of the input vector    
  61.  * @return none.    
  62.  *    
  63.  *\par Description:    
  64.  * \par  
  65.  * The equation used for the conversion process is:    
  66.  *  
  67.  * <pre>    
  68.  *      pDst[n] = (q31_t)(pSrc[n] * 2147483648);   0 <= n < blockSize.    
  69.  * </pre>    
  70.  * <b>Scaling and Overflow Behavior:</b>    
  71.  * \par    
  72.  * The function uses saturating arithmetic.    
  73.  * Results outside of the allowable Q31 range[0x80000000 0x7FFFFFFF] will be saturated.    
  74.  *  
  75.  * \note In order to apply rounding, the library should be rebuilt with the ROUNDING macro    
  76.  * defined in the preprocessor section of project options.    
  77.  */
  78.  
  79.  
  80. void arm_float_to_q31(
  81.   float32_t * pSrc,
  82.   q31_t * pDst,
  83.   uint32_t blockSize)
  84. {
  85.   float32_t *pIn = pSrc;                         /* Src pointer */
  86.   uint32_t blkCnt;                               /* loop counter */
  87.  
  88. #ifdef ARM_MATH_ROUNDING
  89.  
  90.   float32_t in;
  91.  
  92. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  93.  
  94. #ifndef ARM_MATH_CM0_FAMILY
  95.  
  96.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  97.  
  98.   /*loop Unrolling */
  99.   blkCnt = blockSize >> 2u;
  100.  
  101.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
  102.    ** a second loop below computes the remaining 1 to 3 samples. */
  103.   while(blkCnt > 0u)
  104.   {
  105.  
  106. #ifdef ARM_MATH_ROUNDING
  107.  
  108.     /* C = A * 32768 */
  109.     /* convert from float to Q31 and then store the results in the destination buffer */
  110.     in = *pIn++;
  111.     in = (in * 2147483648.0f);
  112.     in += in > 0.0f ? 0.5f : -0.5f;
  113.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  114.  
  115.     in = *pIn++;
  116.     in = (in * 2147483648.0f);
  117.     in += in > 0.0f ? 0.5f : -0.5f;
  118.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  119.  
  120.     in = *pIn++;
  121.     in = (in * 2147483648.0f);
  122.     in += in > 0.0f ? 0.5f : -0.5f;
  123.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  124.  
  125.     in = *pIn++;
  126.     in = (in * 2147483648.0f);
  127.     in += in > 0.0f ? 0.5f : -0.5f;
  128.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  129.  
  130. #else
  131.  
  132.     /* C = A * 2147483648 */
  133.     /* convert from float to Q31 and then store the results in the destination buffer */
  134.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  135.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  136.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  137.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  138.  
  139. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  140.  
  141.     /* Decrement the loop counter */
  142.     blkCnt--;
  143.   }
  144.  
  145.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
  146.    ** No loop unrolling is used. */
  147.   blkCnt = blockSize % 0x4u;
  148.  
  149.   while(blkCnt > 0u)
  150.   {
  151.  
  152. #ifdef ARM_MATH_ROUNDING
  153.  
  154.     /* C = A * 2147483648 */
  155.     /* convert from float to Q31 and then store the results in the destination buffer */
  156.     in = *pIn++;
  157.     in = (in * 2147483648.0f);
  158.     in += in > 0.0f ? 0.5f : -0.5f;
  159.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  160.  
  161. #else
  162.  
  163.     /* C = A * 2147483648 */
  164.     /* convert from float to Q31 and then store the results in the destination buffer */
  165.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  166.  
  167. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  168.  
  169.     /* Decrement the loop counter */
  170.     blkCnt--;
  171.   }
  172.  
  173.  
  174. #else
  175.  
  176.   /* Run the below code for Cortex-M0 */
  177.  
  178.   /* Loop over blockSize number of values */
  179.   blkCnt = blockSize;
  180.  
  181.   while(blkCnt > 0u)
  182.   {
  183.  
  184. #ifdef ARM_MATH_ROUNDING
  185.  
  186.     /* C = A * 2147483648 */
  187.     /* convert from float to Q31 and then store the results in the destination buffer */
  188.     in = *pIn++;
  189.     in = (in * 2147483648.0f);
  190.     in += in > 0 ? 0.5f : -0.5f;
  191.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  192.  
  193. #else
  194.  
  195.     /* C = A * 2147483648 */
  196.     /* convert from float to Q31 and then store the results in the destination buffer */
  197.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  198.  
  199. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  200.  
  201.     /* Decrement the loop counter */
  202.     blkCnt--;
  203.   }
  204.  
  205. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  206.  
  207. }
  208.  
  209. /**    
  210.  * @} end of float_to_x group    
  211.  */
  212.