lib/main/STM32F1/Drivers/CMSIS/DSP_Lib/Source/FastMathFunctions/arm_sin_q15.c

   1 /* ----------------------------------------------------------------------
   2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
   3 *
   4 * $Date:        19. March 2015
   5 * $Revision:    V.1.4.5
   6 *
   7 * Project:          CMSIS DSP Library
   8 * Title:                arm_sin_q15.c
   9 *
  10 * Description:  Fast sine calculation for Q15 values.
  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 #include "arm_common_tables.h"
  43
  44 /**
  45  * @ingroup groupFastMath
  46  */
  47
  48  /**
  49  * @addtogroup sin
  50  * @{
  51  */
  52
  53 /**
  54  * @brief Fast approximation to the trigonometric sine function for Q15 data.
  55  * @param[in] x Scaled input value in radians.
  56  * @return  sin(x).
  57  *
  58  * The Q15 input value is in the range [0 +0.9999] and is mapped to a radian value in the range [0 2*pi).
  59  */
  60
  61 q15_t arm_sin_q15(
  62   q15_t x)
  63 {
  64   q15_t sinVal;                                  /* Temporary variables for input, output */
  65   int32_t index;                                 /* Index variables */
  66   q15_t a, b;                                    /* Four nearest output values */
  67   q15_t fract;                                   /* Temporary values for fractional values */
  68
  69   /* Calculate the nearest index */
  70   index = (uint32_t)x >> FAST_MATH_Q15_SHIFT;
  71
  72   /* Calculation of fractional value */
  73   fract = (x - (index << FAST_MATH_Q15_SHIFT)) << 9;
  74
  75   /* Read two nearest values of input value from the sin table */
  76   a = sinTable_q15[index];
  77   b = sinTable_q15[index+1];
  78
  79   /* Linear interpolation process */
  80   sinVal = (q31_t)(0x8000-fract)*a >> 16;
  81   sinVal = (q15_t)((((q31_t)sinVal << 16) + ((q31_t)fract*b)) >> 16);
  82
  83   return sinVal << 1;
  84 }
  85
  86 /**
  87  * @} end of sin group
  88  */