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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_float_to_q31.c
  4.  * Description:  Converts the elements of the floating-point vector to Q31 vector
  5.  *
  6.  * $Date:        27. January 2017
  7.  * $Revision:    V.1.5.1
  8.  *
  9.  * Target Processor: Cortex-M cores
  10.  * -------------------------------------------------------------------- */
  11. /*
  12.  * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
  13.  *
  14.  * SPDX-License-Identifier: Apache-2.0
  15.  *
  16.  * Licensed under the Apache License, Version 2.0 (the License); you may
  17.  * not use this file except in compliance with the License.
  18.  * You may obtain a copy of the License at
  19.  *
  20.  * www.apache.org/licenses/LICENSE-2.0
  21.  *
  22.  * Unless required by applicable law or agreed to in writing, software
  23.  * distributed under the License is distributed on an AS IS BASIS, WITHOUT
  24.  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  25.  * See the License for the specific language governing permissions and
  26.  * limitations under the License.
  27.  */
  28.  
  29. #include "arm_math.h"
  30.  
  31. /**
  32.  * @ingroup groupSupport
  33.  */
  34.  
  35. /**
  36.  * @defgroup float_to_x  Convert 32-bit floating point value
  37.  */
  38.  
  39. /**
  40.  * @addtogroup float_to_x
  41.  * @{
  42.  */
  43.  
  44. /**
  45.  * @brief Converts the elements of the floating-point vector to Q31 vector.
  46.  * @param[in]       *pSrc points to the floating-point input vector
  47.  * @param[out]      *pDst points to the Q31 output vector
  48.  * @param[in]       blockSize length of the input vector
  49.  * @return none.
  50.  *
  51.  *\par Description:
  52.  * \par
  53.  * The equation used for the conversion process is:
  54.  *
  55.  * <pre>
  56.  *      pDst[n] = (q31_t)(pSrc[n] * 2147483648);   0 <= n < blockSize.
  57.  * </pre>
  58.  * <b>Scaling and Overflow Behavior:</b>
  59.  * \par
  60.  * The function uses saturating arithmetic.
  61.  * Results outside of the allowable Q31 range[0x80000000 0x7FFFFFFF] will be saturated.
  62.  *
  63.  * \note In order to apply rounding, the library should be rebuilt with the ROUNDING macro
  64.  * defined in the preprocessor section of project options.
  65.  */
  66.  
  67.  
  68. void arm_float_to_q31(
  69.   float32_t * pSrc,
  70.   q31_t * pDst,
  71.   uint32_t blockSize)
  72. {
  73.   float32_t *pIn = pSrc;                         /* Src pointer */
  74.   uint32_t blkCnt;                               /* loop counter */
  75.  
  76. #ifdef ARM_MATH_ROUNDING
  77.  
  78.   float32_t in;
  79.  
  80. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  81.  
  82. #if defined (ARM_MATH_DSP)
  83.  
  84.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  85.  
  86.   /*loop Unrolling */
  87.   blkCnt = blockSize >> 2U;
  88.  
  89.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  90.    ** a second loop below computes the remaining 1 to 3 samples. */
  91.   while (blkCnt > 0U)
  92.   {
  93.  
  94. #ifdef ARM_MATH_ROUNDING
  95.  
  96.     /* C = A * 32768 */
  97.     /* convert from float to Q31 and then store the results in the destination buffer */
  98.     in = *pIn++;
  99.     in = (in * 2147483648.0f);
  100.     in += in > 0.0f ? 0.5f : -0.5f;
  101.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  102.  
  103.     in = *pIn++;
  104.     in = (in * 2147483648.0f);
  105.     in += in > 0.0f ? 0.5f : -0.5f;
  106.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  107.  
  108.     in = *pIn++;
  109.     in = (in * 2147483648.0f);
  110.     in += in > 0.0f ? 0.5f : -0.5f;
  111.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  112.  
  113.     in = *pIn++;
  114.     in = (in * 2147483648.0f);
  115.     in += in > 0.0f ? 0.5f : -0.5f;
  116.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  117.  
  118. #else
  119.  
  120.     /* C = A * 2147483648 */
  121.     /* convert from float to Q31 and then store the results in the destination buffer */
  122.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  123.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  124.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  125.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  126.  
  127. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  128.  
  129.     /* Decrement the loop counter */
  130.     blkCnt--;
  131.   }
  132.  
  133.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  134.    ** No loop unrolling is used. */
  135.   blkCnt = blockSize % 0x4U;
  136.  
  137.   while (blkCnt > 0U)
  138.   {
  139.  
  140. #ifdef ARM_MATH_ROUNDING
  141.  
  142.     /* C = A * 2147483648 */
  143.     /* convert from float to Q31 and then store the results in the destination buffer */
  144.     in = *pIn++;
  145.     in = (in * 2147483648.0f);
  146.     in += in > 0.0f ? 0.5f : -0.5f;
  147.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  148.  
  149. #else
  150.  
  151.     /* C = A * 2147483648 */
  152.     /* convert from float to Q31 and then store the results in the destination buffer */
  153.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  154.  
  155. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  156.  
  157.     /* Decrement the loop counter */
  158.     blkCnt--;
  159.   }
  160.  
  161.  
  162. #else
  163.  
  164.   /* Run the below code for Cortex-M0 */
  165.  
  166.   /* Loop over blockSize number of values */
  167.   blkCnt = blockSize;
  168.  
  169.   while (blkCnt > 0U)
  170.   {
  171.  
  172. #ifdef ARM_MATH_ROUNDING
  173.  
  174.     /* C = A * 2147483648 */
  175.     /* convert from float to Q31 and then store the results in the destination buffer */
  176.     in = *pIn++;
  177.     in = (in * 2147483648.0f);
  178.     in += in > 0 ? 0.5f : -0.5f;
  179.     *pDst++ = clip_q63_to_q31((q63_t) (in));
  180.  
  181. #else
  182.  
  183.     /* C = A * 2147483648 */
  184.     /* convert from float to Q31 and then store the results in the destination buffer */
  185.     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
  186.  
  187. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  188.  
  189.     /* Decrement the loop counter */
  190.     blkCnt--;
  191.   }
  192.  
  193. #endif /* #if defined (ARM_MATH_DSP) */
  194.  
  195. }
  196.  
  197. /**
  198.  * @} end of float_to_x group
  199.  */
  200.