lib/main/CMSIS/DSP/Source/SupportFunctions/arm_float_to_q15.c

   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  */