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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_q7.c    
  9. *    
  10. * Description:  Converts the elements of the floating-point vector to Q7 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 Q7 vector.    
  54.  * @param[in]       *pSrc points to the floating-point input vector    
  55.  * @param[out]      *pDst points to the Q7 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] = (q7_t)(pSrc[n] * 128);   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 Q7 range [0x80 0x7F] 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. void arm_float_to_q7(
  76.   float32_t * pSrc,
  77.   q7_t * pDst,
  78.   uint32_t blockSize)
  79. {
  80.   float32_t *pIn = pSrc;                         /* Src pointer */
  81.   uint32_t blkCnt;                               /* loop counter */
  82.  
  83. #ifdef ARM_MATH_ROUNDING
  84.  
  85.   float32_t in;
  86.  
  87. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  88.  
  89. #ifndef ARM_MATH_CM0_FAMILY
  90.  
  91.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  92.  
  93.   /*loop Unrolling */
  94.   blkCnt = blockSize >> 2u;
  95.  
  96.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.    
  97.    ** a second loop below computes the remaining 1 to 3 samples. */
  98.   while(blkCnt > 0u)
  99.   {
  100.  
  101. #ifdef ARM_MATH_ROUNDING
  102.     /* C = A * 128 */
  103.     /* convert from float to q7 and then store the results in the destination buffer */
  104.     in = *pIn++;
  105.     in = (in * 128);
  106.     in += in > 0.0f ? 0.5f : -0.5f;
  107.     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
  108.  
  109.     in = *pIn++;
  110.     in = (in * 128);
  111.     in += in > 0.0f ? 0.5f : -0.5f;
  112.     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
  113.  
  114.     in = *pIn++;
  115.     in = (in * 128);
  116.     in += in > 0.0f ? 0.5f : -0.5f;
  117.     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
  118.  
  119.     in = *pIn++;
  120.     in = (in * 128);
  121.     in += in > 0.0f ? 0.5f : -0.5f;
  122.     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
  123.  
  124. #else
  125.  
  126.     /* C = A * 128 */
  127.     /* convert from float to q7 and then store the results in the destination buffer */
  128.     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
  129.     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
  130.     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
  131.     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
  132.  
  133. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  134.  
  135.     /* Decrement the loop counter */
  136.     blkCnt--;
  137.   }
  138.  
  139.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.    
  140.    ** No loop unrolling is used. */
  141.   blkCnt = blockSize % 0x4u;
  142.  
  143.   while(blkCnt > 0u)
  144.   {
  145.  
  146. #ifdef ARM_MATH_ROUNDING
  147.     /* C = A * 128 */
  148.     /* convert from float to q7 and then store the results in the destination buffer */
  149.     in = *pIn++;
  150.     in = (in * 128);
  151.     in += in > 0.0f ? 0.5f : -0.5f;
  152.     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
  153.  
  154. #else
  155.  
  156.     /* C = A * 128 */
  157.     /* convert from float to q7 and then store the results in the destination buffer */
  158.     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
  159.  
  160. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  161.  
  162.     /* Decrement the loop counter */
  163.     blkCnt--;
  164.   }
  165.  
  166.  
  167. #else
  168.  
  169.   /* Run the below code for Cortex-M0 */
  170.  
  171.  
  172.   /* Loop over blockSize number of values */
  173.   blkCnt = blockSize;
  174.  
  175.   while(blkCnt > 0u)
  176.   {
  177. #ifdef ARM_MATH_ROUNDING
  178.     /* C = A * 128 */
  179.     /* convert from float to q7 and then store the results in the destination buffer */
  180.     in = *pIn++;
  181.     in = (in * 128.0f);
  182.     in += in > 0 ? 0.5f : -0.5f;
  183.     *pDst++ = (q7_t) (__SSAT((q31_t) (in), 8));
  184.  
  185. #else
  186.  
  187.     /* C = A * 128 */
  188.     /* convert from float to q7 and then store the results in the destination buffer */
  189.     *pDst++ = (q7_t) __SSAT((q31_t) (*pIn++ * 128.0f), 8);
  190.  
  191. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  192.  
  193.     /* Decrement the loop counter */
  194.     blkCnt--;
  195.   }
  196.  
  197. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  198.  
  199. }
  200.  
  201. /**    
  202.  * @} end of float_to_x group    
  203.  */
  204.