tmk_core/tool/mbed/mbed-sdk/libraries/dsp/cmsis_dsp/SupportFunctions/arm_float_to_q7.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_q7.c
   9 *
  10 * Description:  Converts the elements of the floating-point vector to Q7 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  * @addtogroup float_to_x
  49  * @{
  50  */
  51
  52 /**
  53  * @brief Converts the elements of the floating-point vector to Q7 vector.
  54  * @param[in]       *pSrc points to the floating-point input vector
  55  * @param[out]      *pDst points to the Q7 output vector
  56  * @param[in]       blockSize length of the input vector
  57  * @return none.
  58  *
  59  *\par Description:
  60  * \par
  61  * The equation used for the conversion process is:
  62  * <pre>
  63  *      pDst[n] = (q7_t)(pSrc[n] * 128);   0 <= n < blockSize.
  64  * </pre>
  65  * \par Scaling and Overflow Behavior:
  66  * \par
  67  * The function uses saturating arithmetic.
  68  * Results outside of the allowable Q7 range [0x80 0x7F] will be saturated.
  69  * \note
  70  * In order to apply rounding, the library should be rebuilt with the ROUNDING macro
  71  * defined in the preprocessor section of project options.
  72  */
  73
  74
  75 void arm_float_to_q7(
  76   float32_t * pSrc,
  77   q7_t * pDst,
  78   uint32_t blockSize)
  79 {
  80   float32_t *pIn = pSrc;                         /* Src pointer */
  81   uint32_t blkCnt;                               /* loop counter */
  82
  83 #ifdef ARM_MATH_ROUNDING
  84
  85   float32_t in;
  86
  87 #endif /*      #ifdef ARM_MATH_ROUNDING        */
  88
  89 #ifndef ARM_MATH_CM0_FAMILY
  90
  91   /* Run the below code for Cortex-M4 and Cortex-M3 */
  92
  93   /*loop Unrolling */
  94   blkCnt = blockSize >> 2u;
  95
  96   /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
  97    ** a second loop below computes the remaining 1 to 3 samples. */
  98   while(blkCnt > 0u)
  99   {
 100
 101 #ifdef ARM_MATH_ROUNDING
 102     /* C = A * 128 */
 103     /* convert from float to q7 and then store the results in the destination buffer */
 104     in = *pIn++;
 105     in = (in * 128);
 106     in += in > 0 ? 0.5 : -0.5;
 107     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
 108
 109     in = *pIn++;
 110     in = (in * 128);
 111     in += in > 0 ? 0.5 : -0.5;
 112     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
 113
 114     in = *pIn++;
 115     in = (in * 128);
 116     in += in > 0 ? 0.5 : -0.5;
 117     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
 118
 119     in = *pIn++;
 120     in = (in * 128);
 121     in += in > 0 ? 0.5 : -0.5;
 122     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
 123
 124 #else
 125
 126     /* C = A * 128 */
 127     /* convert from float to q7 and then store the results in the destination buffer */
 128     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 129     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 130     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 131     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 132
 133 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 134
 135     /* Decrement the loop counter */
 136     blkCnt--;
 137   }
 138
 139   /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
 140    ** No loop unrolling is used. */
 141   blkCnt = blockSize % 0x4u;
 142
 143   while(blkCnt > 0u)
 144   {
 145
 146 #ifdef ARM_MATH_ROUNDING
 147     /* C = A * 128 */
 148     /* convert from float to q7 and then store the results in the destination buffer */
 149     in = *pIn++;
 150     in = (in * 128);
 151     in += in > 0 ? 0.5 : -0.5;
 152     *pDst++ = (q7_t) (__SSAT((q15_t) (in), 8));
 153
 154 #else
 155
 156     /* C = A * 128 */
 157     /* convert from float to q7 and then store the results in the destination buffer */
 158     *pDst++ = __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 159
 160 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 161
 162     /* Decrement the loop counter */
 163     blkCnt--;
 164   }
 165
 166
 167 #else
 168
 169   /* Run the below code for Cortex-M0 */
 170
 171
 172   /* Loop over blockSize number of values */
 173   blkCnt = blockSize;
 174
 175   while(blkCnt > 0u)
 176   {
 177 #ifdef ARM_MATH_ROUNDING
 178     /* C = A * 128 */
 179     /* convert from float to q7 and then store the results in the destination buffer */
 180     in = *pIn++;
 181     in = (in * 128.0f);
 182     in += in > 0 ? 0.5f : -0.5f;
 183     *pDst++ = (q7_t) (__SSAT((q31_t) (in), 8));
 184
 185 #else
 186
 187     /* C = A * 128 */
 188     /* convert from float to q7 and then store the results in the destination buffer */
 189     *pDst++ = (q7_t) __SSAT((q31_t) (*pIn++ * 128.0f), 8);
 190
 191 #endif /*      #ifdef ARM_MATH_ROUNDING        */
 192
 193     /* Decrement the loop counter */
 194     blkCnt--;
 195   }
 196
 197 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
 198
 199 }
 200
 201 /**
 202  * @} end of float_to_x group
 203  */