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  1. /* ----------------------------------------------------------------------
  2.  * Project:      CMSIS DSP Library
  3.  * Title:        arm_float_to_q15.c
  4.  * Description:  Converts the elements of the floating-point vector to Q15 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.  * @addtogroup float_to_x
  37.  * @{
  38.  */
  39.  
  40. /**
  41.  * @brief Converts the elements of the floating-point vector to Q15 vector.
  42.  * @param[in]       *pSrc points to the floating-point input vector
  43.  * @param[out]      *pDst points to the Q15 output vector
  44.  * @param[in]       blockSize length of the input vector
  45.  * @return none.
  46.  *
  47.  * \par Description:
  48.  * \par
  49.  * The equation used for the conversion process is:
  50.  * <pre>
  51.  *      pDst[n] = (q15_t)(pSrc[n] * 32768);   0 <= n < blockSize.
  52.  * </pre>
  53.  * \par Scaling and Overflow Behavior:
  54.  * \par
  55.  * The function uses saturating arithmetic.
  56.  * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
  57.  * \note
  58.  * In order to apply rounding, the library should be rebuilt with the ROUNDING macro
  59.  * defined in the preprocessor section of project options.
  60.  *
  61.  */
  62.  
  63.  
  64. void arm_float_to_q15(
  65.   float32_t * pSrc,
  66.   q15_t * pDst,
  67.   uint32_t blockSize)
  68. {
  69.   float32_t *pIn = pSrc;                         /* Src pointer */
  70.   uint32_t blkCnt;                               /* loop counter */
  71.  
  72. #ifdef ARM_MATH_ROUNDING
  73.  
  74.   float32_t in;
  75.  
  76. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  77.  
  78. #if defined (ARM_MATH_DSP)
  79.  
  80.   /* Run the below code for Cortex-M4 and Cortex-M3 */
  81.  
  82.   /*loop Unrolling */
  83.   blkCnt = blockSize >> 2U;
  84.  
  85.   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  86.    ** a second loop below computes the remaining 1 to 3 samples. */
  87.   while (blkCnt > 0U)
  88.   {
  89.  
  90. #ifdef ARM_MATH_ROUNDING
  91.     /* C = A * 32768 */
  92.     /* convert from float to q15 and then store the results in the destination buffer */
  93.     in = *pIn++;
  94.     in = (in * 32768.0f);
  95.     in += in > 0.0f ? 0.5f : -0.5f;
  96.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  97.  
  98.     in = *pIn++;
  99.     in = (in * 32768.0f);
  100.     in += in > 0.0f ? 0.5f : -0.5f;
  101.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  102.  
  103.     in = *pIn++;
  104.     in = (in * 32768.0f);
  105.     in += in > 0.0f ? 0.5f : -0.5f;
  106.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  107.  
  108.     in = *pIn++;
  109.     in = (in * 32768.0f);
  110.     in += in > 0.0f ? 0.5f : -0.5f;
  111.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  112.  
  113. #else
  114.  
  115.     /* C = A * 32768 */
  116.     /* convert from float to q15 and then store the results in the destination buffer */
  117.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  118.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  119.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  120.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  121.  
  122. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  123.  
  124.     /* Decrement the loop counter */
  125.     blkCnt--;
  126.   }
  127.  
  128.   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  129.    ** No loop unrolling is used. */
  130.   blkCnt = blockSize % 0x4U;
  131.  
  132.   while (blkCnt > 0U)
  133.   {
  134.  
  135. #ifdef ARM_MATH_ROUNDING
  136.     /* C = A * 32768 */
  137.     /* convert from float to q15 and then store the results in the destination buffer */
  138.     in = *pIn++;
  139.     in = (in * 32768.0f);
  140.     in += in > 0.0f ? 0.5f : -0.5f;
  141.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  142.  
  143. #else
  144.  
  145.     /* C = A * 32768 */
  146.     /* convert from float to q15 and then store the results in the destination buffer */
  147.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  148.  
  149. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  150.  
  151.     /* Decrement the loop counter */
  152.     blkCnt--;
  153.   }
  154.  
  155.  
  156. #else
  157.  
  158.   /* Run the below code for Cortex-M0 */
  159.  
  160.   /* Loop over blockSize number of values */
  161.   blkCnt = blockSize;
  162.  
  163.   while (blkCnt > 0U)
  164.   {
  165.  
  166. #ifdef ARM_MATH_ROUNDING
  167.     /* C = A * 32768 */
  168.     /* convert from float to q15 and then store the results in the destination buffer */
  169.     in = *pIn++;
  170.     in = (in * 32768.0f);
  171.     in += in > 0 ? 0.5f : -0.5f;
  172.     *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  173.  
  174. #else
  175.  
  176.     /* C = A * 32768 */
  177.     /* convert from float to q15 and then store the results in the destination buffer */
  178.     *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  179.  
  180. #endif /*      #ifdef ARM_MATH_ROUNDING        */
  181.  
  182.     /* Decrement the loop counter */
  183.     blkCnt--;
  184.   }
  185.  
  186. #endif /* #if defined (ARM_MATH_DSP) */
  187.  
  188. }
  189.  
  190. /**
  191.  * @} end of float_to_x group
  192.  */
  193.