lib/main/CMSIS/DSP/Source/SupportFunctions/arm_float_to_q31.c

   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  */