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  1. /* ----------------------------------------------------------------------
  2. * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
  3. *
  4. * $Date:        21. September 2015
  5. * $Revision:    V.1.4.5 a
  6. *
  7. * Project:      CMSIS DSP Library
  8. * Title:        arm_sin_f32.c
  9. *
  10. * Description:  Fast sine calculation for floating-point 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. #include <math.h>
  44.  
  45. /**
  46.  * @ingroup groupFastMath
  47.  */
  48.  
  49. /**
  50.  * @defgroup sin Sine
  51.  *
  52.  * Computes the trigonometric sine function using a combination of table lookup
  53.  * and linear interpolation.  There are separate functions for
  54.  * Q15, Q31, and floating-point data types.
  55.  * The input to the floating-point version is in radians while the
  56.  * fixed-point Q15 and Q31 have a scaled input with the range
  57.  * [0 +0.9999] mapping to [0 2*pi).  The fixed-point range is chosen so that a
  58.  * value of 2*pi wraps around to 0.
  59.  *
  60.  * The implementation is based on table lookup using 256 values together with linear interpolation.
  61.  * The steps used are:
  62.  *  -# Calculation of the nearest integer table index
  63.  *  -# Compute the fractional portion (fract) of the table index.
  64.  *  -# The final result equals <code>(1.0f-fract)*a + fract*b;</code>
  65.  *
  66.  * where
  67.  * <pre>
  68.  *    b=Table[index+0];
  69.  *    c=Table[index+1];
  70.  * </pre>
  71.  */
  72.  
  73. /**
  74.  * @addtogroup sin
  75.  * @{
  76.  */
  77.  
  78. /**
  79.  * @brief  Fast approximation to the trigonometric sine function for floating-point data.
  80.  * @param[in] x input value in radians.
  81.  * @return  sin(x).
  82.  */
  83.  
  84. float32_t arm_sin_f32(
  85.   float32_t x)
  86. {
  87.   float32_t sinVal, fract, in;                           /* Temporary variables for input, output */
  88.   uint16_t index;                                        /* Index variable */
  89.   float32_t a, b;                                        /* Two nearest output values */
  90.   int32_t n;
  91.   float32_t findex;
  92.  
  93.   /* input x is in radians */
  94.   /* Scale the input to [0 1] range from [0 2*PI] , divide input by 2*pi */
  95.   in = x * 0.159154943092f;
  96.  
  97.   /* Calculation of floor value of input */
  98.   n = (int32_t) in;
  99.  
  100.   /* Make negative values towards -infinity */
  101.   if(x < 0.0f)
  102.   {
  103.     n--;
  104.   }
  105.  
  106.   /* Map input value to [0 1] */
  107.   in = in - (float32_t) n;
  108.  
  109.   /* Calculation of index of the table */
  110.   findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
  111.   if (findex >= 512.0f) {
  112.     findex -= 512.0f;
  113.   }
  114.  
  115.   index = ((uint16_t)findex) & 0x1ff;
  116.  
  117.   /* fractional value calculation */
  118.   fract = findex - (float32_t) index;
  119.  
  120.   /* Read two nearest values of input value from the sin table */
  121.   a = sinTable_f32[index];
  122.   b = sinTable_f32[index+1];
  123.  
  124.   /* Linear interpolation process */
  125.   sinVal = (1.0f-fract)*a + fract*b;
  126.  
  127.   /* Return the output value */
  128.   return (sinVal);
  129. }
  130.  
  131. /**
  132.  * @} end of sin group
  133.  */
  134.