/* ----------------------------------------------------------------------
* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
*
* $Date: 16/10/14 6:01p $Revision:    V.1.4.5 a
*
* Project:      CMSIS DSP Library
* Title:        arm_sin_f32.c
*
* Description:  Fast sine calculation for floating-point values.
*
* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
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*     notice, this list of conditions and the following disclaimer.
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in
*     the documentation and/or other materials provided with the
*     distribution.
*   - Neither the name of ARM LIMITED nor the names of its contributors
*     may be used to endorse or promote products derived from this
*     software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* -------------------------------------------------------------------- */

#include "arm_math.h"
#include "arm_common_tables.h"
#include <math.h>

/**
 * @ingroup groupFastMath
 */

/**
 * @defgroup sin Sine
 *
 * Computes the trigonometric sine function using a combination of table lookup
 * and linear interpolation.  There are separate functions for
 * Q15, Q31, and floating-point data types.
 * The input to the floating-point version is in radians while the
 * fixed-point Q15 and Q31 have a scaled input with the range
 * [0 +0.9999] mapping to [0 2*pi).  The fixed-point range is chosen so that a
 * value of 2*pi wraps around to 0.
 *
 * The implementation is based on table lookup using 256 values together with linear interpolation.
 * The steps used are:
 *  -# Calculation of the nearest integer table index
 *  -# Compute the fractional portion (fract) of the table index.
 *  -# The final result equals <code>(1.0f-fract)*a + fract*b;</code>
 *
 * where
 * <pre>
 *    b=Table[index+0];
 *    c=Table[index+1];
 * </pre>
 */

/**
 * @addtogroup sin
 * @{
 */

/**
 * @brief  Fast approximation to the trigonometric sine function for floating-point data.
 * @param[in] x input value in radians.
 * @return  sin(x).
 */

float32_t arm_sin_f32(
    float32_t x)
{
    float32_t sinVal, fract, in;                           /* Temporary variables for input, output */
    uint16_t index;                                        /* Index variable */
    float32_t a, b;                                        /* Two nearest output values */
    int32_t n;
    float32_t findex;

    /* input x is in radians */
    /* Scale the input to [0 1] range from [0 2*PI] , divide input by 2*pi */
    in = x * 0.159154943092f;

    /* Calculation of floor value of input */
    n = (int32_t) in;

    /* Make negative values towards -infinity */
    if(x < 0.0f)
    {
        n--;
    }

    /* Map input value to [0 1] */
    in = in - (float32_t) n;

    /* Calculation of index of the table */
    findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
    if(findex >= 512.0f)
    {
        findex -= 512.0f;
    }

    index = ((uint16_t)findex) & 0x1ff;

    /* fractional value calculation */
    fract = findex - (float32_t) index;

    /* Read two nearest values of input value from the sin table */
    a = sinTable_f32[index];
    b = sinTable_f32[index + 1];

    /* Linear interpolation process */
    sinVal = (1.0f - fract) * a + fract * b;

    /* Return the output value */
    return (sinVal);
}

/**
 * @} end of sin group
 */
