/* @(#)k_sin.c 1.2 95/01/04 */
/* $Id: k_sin.c,v 1.3 2010/05/12 07:07:15 anczane1 Exp $ */
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

/* __kernel_sin( x, y, iy)
 * kernel sin function on [-pi/4, pi/4], pi/4 ~ 0.7854
 * Input x is assumed to be bounded by ~pi/4 in magnitude.
 * Input y is the tail of x.
 * Input iy indicates whether y is 0. (if iy=0, y assume to be 0).
 *
 * Algorithm
 *	1. Since sin(-x) = -sin(x), we need only to consider positive x.
 *	2. if x < 2^-27 (hx<0x3e400000 0), return x with inexact if x!=0.
 *	3. sin(x) is approximated by a polynomial of degree 13 on
 *	   [0,pi/4]
 *		  	         3            13
 *	   	sin(x) ~ x + S1*x + ... + S6*x
 *	   where
 *
 * 	|sin(x)         2     4     6     8     10     12  |     -58
 * 	|----- - (1+S1*x +S2*x +S3*x +S4*x +S5*x  +S6*x   )| <= 2
 * 	|  x 					           |
 *
 *	4. sin(x+y) = sin(x) + sin'(x')*y
 *		    ~ sin(x) + (1-x*x/2)*y
 *	   For better accuracy, let
 *		     3      2      2      2      2
 *		r = x *(S2+x *(S3+x *(S4+x *(S5+x *S6))))
 *	   then                   3    2
 *		sin(x) = x + (S1*x + (x *(r-y/2)+y))
 */

#include <ansi_parms.h>

#if _EWL_FLOATING_POINT && _EWL_USES_SUN_DP_MATH_LIB

#include <fdlibm.h>

#ifdef __STDC__
static const f64_t
#else
static f64_t
#endif
half =  5.00000000000000000000e-01, /* 0x3FE00000, 0x00000000 */
S1  = -1.66666666666666324348e-01, /* 0xBFC55555, 0x55555549 */
S2  =  8.33333333332248946124e-03, /* 0x3F811111, 0x1110F8A6 */
S3  = -1.98412698298579493134e-04, /* 0xBF2A01A0, 0x19C161D5 */
S4  =  2.75573137070700676789e-06, /* 0x3EC71DE3, 0x57B1FE7D */
S5  = -2.50507602534068634195e-08, /* 0xBE5AE5E6, 0x8A2B9CEB */
S6  =  1.58969099521155010221e-10; /* 0x3DE5D93A, 0x5ACFD57C */

#ifdef __STDC__
	f64_t _EWL_MATH_CDECL __kernel_sin(f64_t x, f64_t y, int32_t iy)
#else
	f64_t __kernel_sin(x, y, iy)
	f64_t x,y; int32_t iy;		/* iy=0 if y is zero */
#endif
{
	f64_t z,r,v;
	uint32_t ix;
	ix = GET_DOUBLE_UHI_WORD(x)&0x7fffffffu;	/* high word of x */
	if ((ix<0x3e400000u) && ((int32_t)x==0L)) {	/* |x| < 2**-27 */
		MISRA_EXCEPTION_RULE_14_7()
		return x;		/* generate inexact */
	}
	z	=  x*x;
	v	=  z*x;
	r	=  S2+(z*(S3+(z*(S4+(z*(S5+(z*S6)))))));
	if(iy==0L){
		MISRA_EXCEPTION_RULE_14_7()
		return x+(v*(S1+(z*r)));
	}
	else  {
		MISRA_EXCEPTION_RULE_14_7()
		return x-(((z*((half*y)-(v*r)))-y)-(v*S1));
	}
}
#endif /* _EWL_FLOATING_POINT  */
