tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/SupportFunctions/arm_q31_to_float.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_q31_to_float.c
   9 *
  10 * Description:  Converts the elements of the Q31 vector to floating-point 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 q31_to_x  Convert 32-bit Integer value
  49  */
  50
  51 /**
  52  * @addtogroup q31_to_x
  53  * @{
  54  */
  55
  56 /**
  57  * @brief Converts the elements of the Q31 vector to floating-point vector.
  58  * @param[in]       *pSrc points to the Q31 input vector
  59  * @param[out]      *pDst points to the floating-point output vector
  60  * @param[in]       blockSize length of the input vector
  61  * @return none.
  62  *
  63  * \par Description:
  64  *
  65  * The equation used for the conversion process is:
  66  *
  67  * <pre>
  68  *      pDst[n] = (float32_t) pSrc[n] / 2147483648;   0 <= n < blockSize.
  69  * </pre>
  70  *
  71  */
  72
  73
  74 void arm_q31_to_float(
  75   q31_t * pSrc,
  76   float32_t * pDst,
  77   uint32_t blockSize)
  78 {
  79   q31_t *pIn = pSrc;                             /* Src pointer */
  80   uint32_t blkCnt;                               /* loop counter */
  81
  82
  83 #ifndef ARM_MATH_CM0_FAMILY
  84
  85   /* Run the below code for Cortex-M4 and Cortex-M3 */
  86
  87   /*loop Unrolling */
  88   blkCnt = blockSize >> 2u;
  89
  90   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  91    ** a second loop below computes the remaining 1 to 3 samples. */
  92   while(blkCnt > 0u)
  93   {
  94     /* C = (float32_t) A / 2147483648 */
  95     /* convert from q31 to float and then store the results in the destination buffer */
  96     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  97     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  98     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
  99     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
 100
 101     /* Decrement the loop counter */
 102     blkCnt--;
 103   }
 104
 105   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 106    ** No loop unrolling is used. */
 107   blkCnt = blockSize % 0x4u;
 108
 109 #else
 110
 111   /* Run the below code for Cortex-M0 */
 112
 113   /* Loop over blockSize number of values */
 114   blkCnt = blockSize;
 115
 116 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 117
 118   while(blkCnt > 0u)
 119   {
 120     /* C = (float32_t) A / 2147483648 */
 121     /* convert from q31 to float and then store the results in the destination buffer */
 122     *pDst++ = ((float32_t) * pIn++ / 2147483648.0f);
 123
 124     /* Decrement the loop counter */
 125     blkCnt--;
 126   }
 127 }
 128
 129 /**
 130  * @} end of q31_to_x group
 131  */