tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/SupportFunctions/arm_float_to_q31.c

   1 /* ----------------------------------------------------------------------------
   2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        17. January 2013
   5 * $Revision:    V1.4.1
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:                arm_float_to_q31.c
   9 *
  10 * Description:  Converts the elements of the floating-point vector to Q31 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  * @defgroup float_to_x  Convert 32-bit floating point value
  49  */
  50
  51 /**
  52  * @addtogroup float_to_x
  53  * @{
  54  */
  55
  56 /**
  57  * @brief Converts the elements of the floating-point vector to Q31 vector.
  58  * @param[in]       *pSrc points to the floating-point input vector
  59  * @param[out]      *pDst points to the Q31 output vector
  60  * @param[in]       blockSize length of the input vector
  61  * @return none.
  62  *
  63  *\par Description:
  64  * \par
  65  * The equation used for the conversion process is:
  66  *
  67  * <pre>
  68  *      pDst[n] = (q31_t)(pSrc[n] * 2147483648);   0 <= n < blockSize.
  69  * </pre>
  70  * <b>Scaling and Overflow Behavior:</b>
  71  * \par
  72  * The function uses saturating arithmetic.
  73  * Results outside of the allowable Q31 range[0x80000000 0x7FFFFFFF] will be saturated.
  74  *
  75  * \note In order to apply rounding, the library should be rebuilt with the ROUNDING macro
  76  * defined in the preprocessor section of project options.
  77  */
  78
  79
  80 void arm_float_to_q31(
  81   float32_t * pSrc,
  82   q31_t * pDst,
  83   uint32_t blockSize)
  84 {
  85   float32_t *pIn = pSrc;                         /* Src pointer */
  86   uint32_t blkCnt;                               /* loop counter */
  87
  88 #ifdef ARM_MATH_ROUNDING
  89
  90   float32_t in;
  91
  92 #endif /*      #ifdef ARM_MATH_ROUNDING        */
  93
  94 #ifndef ARM_MATH_CM0_FAMILY
  95
  96   /* Run the below code for Cortex-M4 and Cortex-M3 */
  97
  98   /*loop Unrolling */
  99   blkCnt = blockSize >> 2u;
 100
 101   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
 102    ** a second loop below computes the remaining 1 to 3 samples. */
 103   while(blkCnt > 0u)
 104   {
 105
 106 #ifdef ARM_MATH_ROUNDING
 107
 108     /* C = A * 32768 */
 109     /* convert from float to Q31 and then store the results in the destination buffer */
 110     in = *pIn++;
 111     in = (in * 2147483648.0f);
 112     in += in > 0 ? 0.5 : -0.5;
 113     *pDst++ = clip_q63_to_q31((q63_t) (in));
 114
 115     in = *pIn++;
 116     in = (in * 2147483648.0f);
 117     in += in > 0 ? 0.5 : -0.5;
 118     *pDst++ = clip_q63_to_q31((q63_t) (in));
 119
 120     in = *pIn++;
 121     in = (in * 2147483648.0f);
 122     in += in > 0 ? 0.5 : -0.5;
 123     *pDst++ = clip_q63_to_q31((q63_t) (in));
 124
 125     in = *pIn++;
 126     in = (in * 2147483648.0f);
 127     in += in > 0 ? 0.5 : -0.5;
 128     *pDst++ = clip_q63_to_q31((q63_t) (in));
 129
 130 #else
 131
 132     /* C = A * 2147483648 */
 133     /* convert from float to Q31 and then store the results in the destination buffer */
 134     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
 135     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
 136     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
 137     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
 138
 139 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 140
 141     /* Decrement the loop counter */
 142     blkCnt--;
 143   }
 144
 145   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 146    ** No loop unrolling is used. */
 147   blkCnt = blockSize % 0x4u;
 148
 149   while(blkCnt > 0u)
 150   {
 151
 152 #ifdef ARM_MATH_ROUNDING
 153
 154     /* C = A * 2147483648 */
 155     /* convert from float to Q31 and then store the results in the destination buffer */
 156     in = *pIn++;
 157     in = (in * 2147483648.0f);
 158     in += in > 0 ? 0.5 : -0.5;
 159     *pDst++ = clip_q63_to_q31((q63_t) (in));
 160
 161 #else
 162
 163     /* C = A * 2147483648 */
 164     /* convert from float to Q31 and then store the results in the destination buffer */
 165     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
 166
 167 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 168
 169     /* Decrement the loop counter */
 170     blkCnt--;
 171   }
 172
 173
 174 #else
 175
 176   /* Run the below code for Cortex-M0 */
 177
 178   /* Loop over blockSize number of values */
 179   blkCnt = blockSize;
 180
 181   while(blkCnt > 0u)
 182   {
 183
 184 #ifdef ARM_MATH_ROUNDING
 185
 186     /* C = A * 2147483648 */
 187     /* convert from float to Q31 and then store the results in the destination buffer */
 188     in = *pIn++;
 189     in = (in * 2147483648.0f);
 190     in += in > 0 ? 0.5f : -0.5f;
 191     *pDst++ = clip_q63_to_q31((q63_t) (in));
 192
 193 #else
 194
 195     /* C = A * 2147483648 */
 196     /* convert from float to Q31 and then store the results in the destination buffer */
 197     *pDst++ = clip_q63_to_q31((q63_t) (*pIn++ * 2147483648.0f));
 198
 199 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 200
 201     /* Decrement the loop counter */
 202     blkCnt--;
 203   }
 204
 205 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 206
 207 }
 208
 209 /**
 210  * @} end of float_to_x group
 211  */