[picodrive.git] / platform / gp2x / code940 / uClibc / s_sin.c

/* @(#)s_sin.c 5.1 93/09/24 */
/*
 * ====================================================
 * 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.
 * ====================================================
 */

#if defined(LIBM_SCCS) && !defined(lint)
static char rcsid[] = "$NetBSD: s_sin.c,v 1.7 1995/05/10 20:48:15 jtc Exp $";
#endif

/* sin(x)
 * Return sine function of x.
 *
 * kernel function:
 *	__kernel_sin		... sine function on [-pi/4,pi/4]
 *	__kernel_cos		... cose function on [-pi/4,pi/4]
 *	__ieee754_rem_pio2	... argument reduction routine
 *
 * Method.
 *      Let S,C and T denote the sin, cos and tan respectively on
 *	[-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
 *	in [-pi/4 , +pi/4], and let n = k mod 4.
 *	We have
 *
 *          n        sin(x)      cos(x)        tan(x)
 *     ----------------------------------------------------------
 *	    0	       S	   C		 T
 *	    1	       C	  -S		-1/T
 *	    2	      -S	  -C		 T
 *	    3	      -C	   S		-1/T
 *     ----------------------------------------------------------
 *
 * Special cases:
 *      Let trig be any of sin, cos, or tan.
 *      trig(+-INF)  is NaN, with signals;
 *      trig(NaN)    is that NaN;
 *
 * Accuracy:
 *	TRIG(x) returns trig(x) nearly rounded
 */

#include "math.h"
#include "math_private.h"

#ifdef __STDC__
	double sin(double x)
#else
	double sin(x)
	double x;
#endif
{
	double y[2],z=0.0;
	int32_t n, ix;

    /* High word of x. */
	GET_HIGH_WORD(ix,x);

    /* |x| ~< pi/4 */
	ix &= 0x7fffffff;
	if(ix <= 0x3fe921fb) return __kernel_sin(x,z,0);

    /* sin(Inf or NaN) is NaN */
	else if (ix>=0x7ff00000) return x-x;

    /* argument reduction needed */
	else {
	    n = __ieee754_rem_pio2(x,y);
	    switch(n&3) {
		case 0: return  __kernel_sin(y[0],y[1],1);
		case 1: return  __kernel_cos(y[0],y[1]);
		case 2: return -__kernel_sin(y[0],y[1],1);
		default:
			return -__kernel_cos(y[0],y[1]);
	    }
	}
}
Commit	Line	Data
	1	/* @(#)s_sin.c 5.1 93/09/24 */
	2	/*
	3	* ====================================================
	4	* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
	5	*
	6	* Developed at SunPro, a Sun Microsystems, Inc. business.
	7	* Permission to use, copy, modify, and distribute this
	8	* software is freely granted, provided that this notice
	9	* is preserved.
	10	* ====================================================
	11	*/
	12
	13	#if defined(LIBM_SCCS) && !defined(lint)
	14	static char rcsid[] = "$NetBSD: s_sin.c,v 1.7 1995/05/10 20:48:15 jtc Exp $";
	15	#endif
	16
	17	/* sin(x)
	18	* Return sine function of x.
	19	*
	20	* kernel function:
	21	* __kernel_sin ... sine function on [-pi/4,pi/4]
	22	* __kernel_cos ... cose function on [-pi/4,pi/4]
	23	* __ieee754_rem_pio2 ... argument reduction routine
	24	*
	25	* Method.
	26	* Let S,C and T denote the sin, cos and tan respectively on
	27	* [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
	28	* in [-pi/4 , +pi/4], and let n = k mod 4.
	29	* We have
	30	*
	31	* n sin(x) cos(x) tan(x)
	32	* ----------------------------------------------------------
	33	* 0 S C T
	34	* 1 C -S -1/T
	35	* 2 -S -C T
	36	* 3 -C S -1/T
	37	* ----------------------------------------------------------
	38	*
	39	* Special cases:
	40	* Let trig be any of sin, cos, or tan.
	41	* trig(+-INF) is NaN, with signals;
	42	* trig(NaN) is that NaN;
	43	*
	44	* Accuracy:
	45	* TRIG(x) returns trig(x) nearly rounded
	46	*/
	47
	48	#include "math.h"
	49	#include "math_private.h"
	50
	51	#ifdef __STDC__
	52	double sin(double x)
	53	#else
	54	double sin(x)
	55	double x;
	56	#endif
	57	{
	58	double y[2],z=0.0;
	59	int32_t n, ix;
	60
	61	/* High word of x. */
	62	GET_HIGH_WORD(ix,x);
	63
	64	/* \|x\| ~< pi/4 */
	65	ix &= 0x7fffffff;
	66	if(ix <= 0x3fe921fb) return __kernel_sin(x,z,0);
	67
	68	/* sin(Inf or NaN) is NaN */
	69	else if (ix>=0x7ff00000) return x-x;
	70
	71	/* argument reduction needed */
	72	else {
	73	n = __ieee754_rem_pio2(x,y);
	74	switch(n&3) {
	75	case 0: return __kernel_sin(y[0],y[1],1);
	76	case 1: return __kernel_cos(y[0],y[1]);
	77	case 2: return -__kernel_sin(y[0],y[1],1);
	78	default:
	79	return -__kernel_cos(y[0],y[1]);
	80	}
	81	}
	82	}