arm_sin_f32.c

00001 /* ----------------------------------------------------------------------
00002 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
00003 *
00004 * $Date:        21. September 2015
00005 * $Revision:    V.1.4.5 a
00006 *
00007 * Project:      CMSIS DSP Library
00008 * Title:        arm_sin_f32.c
00009 *
00010 * Description:  Fast sine calculation for floating-point values.
00011 *
00012 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
00013 *
00014 * Redistribution and use in source and binary forms, with or without
00015 * modification, are permitted provided that the following conditions
00016 * are met:
00017 *   - Redistributions of source code must retain the above copyright
00018 *     notice, this list of conditions and the following disclaimer.
00019 *   - Redistributions in binary form must reproduce the above copyright
00020 *     notice, this list of conditions and the following disclaimer in
00021 *     the documentation and/or other materials provided with the
00022 *     distribution.
00023 *   - Neither the name of ARM LIMITED nor the names of its contributors
00024 *     may be used to endorse or promote products derived from this
00025 *     software without specific prior written permission.
00026 *
00027 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00028 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00029 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00030 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
00031 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00032 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00033 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
00034 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
00035 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
00036 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
00037 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00038 * POSSIBILITY OF SUCH DAMAGE.
00039 * -------------------------------------------------------------------- */
00040 
00041 #include "arm_math.h"
00042 #include "arm_common_tables.h"
00043 #include <math.h>
00044 
00045 /**
00046  * @ingroup groupFastMath
00047  */
00048 
00049 /**
00050  * @defgroup sin Sine
00051  *
00052  * Computes the trigonometric sine function using a combination of table lookup
00053  * and linear interpolation.  There are separate functions for
00054  * Q15, Q31, and floating-point data types.
00055  * The input to the floating-point version is in radians while the
00056  * fixed-point Q15 and Q31 have a scaled input with the range
00057  * [0 +0.9999] mapping to [0 2*pi).  The fixed-point range is chosen so that a
00058  * value of 2*pi wraps around to 0.
00059  *
00060  * The implementation is based on table lookup using 256 values together with linear interpolation.
00061  * The steps used are:
00062  *  -# Calculation of the nearest integer table index
00063  *  -# Compute the fractional portion (fract) of the table index.
00064  *  -# The final result equals <code>(1.0f-fract)*a + fract*b;</code>
00065  *
00066  * where
00067  * <pre>
00068  *    b=Table[index+0];
00069  *    c=Table[index+1];
00070  * </pre>
00071  */
00072 
00073 /**
00074  * @addtogroup sin
00075  * @{
00076  */
00077 
00078 /**
00079  * @brief  Fast approximation to the trigonometric sine function for floating-point data.
00080  * @param[in] x input value in radians.
00081  * @return  sin(x).
00082  */
00083 
00084 float32_t arm_sin_f32(
00085   float32_t x)
00086 {
00087   float32_t sinVal, fract, in;                           /* Temporary variables for input, output */
00088   uint16_t index;                                        /* Index variable */
00089   float32_t a, b;                                        /* Two nearest output values */
00090   int32_t n;
00091   float32_t findex;
00092 
00093   /* input x is in radians */
00094   /* Scale the input to [0 1] range from [0 2*PI] , divide input by 2*pi */
00095   in = x * 0.159154943092f;
00096 
00097   /* Calculation of floor value of input */
00098   n = (int32_t) in;
00099 
00100   /* Make negative values towards -infinity */
00101   if(x < 0.0f)
00102   {
00103     n--;
00104   }
00105 
00106   /* Map input value to [0 1] */
00107   in = in - (float32_t) n;
00108 
00109   /* Calculation of index of the table */
00110   findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
00111   if (findex >= 512.0f) {
00112     findex -= 512.0f;
00113   }
00114 
00115   index = ((uint16_t)findex) & 0x1ff;
00116 
00117   /* fractional value calculation */
00118   fract = findex - (float32_t) index;
00119 
00120   /* Read two nearest values of input value from the sin table */
00121   a = sinTable_f32[index];
00122   b = sinTable_f32[index+1];
00123 
00124   /* Linear interpolation process */
00125   sinVal = (1.0f-fract)*a + fract*b;
00126 
00127   /* Return the output value */
00128   return (sinVal);
00129 }
00130 
00131 /**
00132  * @} end of sin group
00133  */