s_sinf.c

来自「Glibc 2.3.2源代码(解压后有100多M)」· C语言 代码 · 共 55 行

/* s_sinf.c -- float version of s_sin.c.
 * Conversion to float by Ian Lance Taylor, Cygnus Support, [e-mail].
 */

/*
 * ====================================================
 * 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_sinf.c,v 1.4 1995/05/10 20:48:16 jtc Exp $";
#endif

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

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

	GET_FLOAT_WORD(ix,x);

    /* |x| ~< pi/4 */
	ix &= 0x7fffffff;
	if(ix <= 0x3f490fd8) return __kernel_sinf(x,z,0);

    /* sin(Inf or NaN) is NaN */
	else if (ix>=0x7f800000) return x-x;

    /* argument reduction needed */
	else {
	    n = __ieee754_rem_pio2f(x,y);
	    switch(n&3) {
		case 0: return  __kernel_sinf(y[0],y[1],1);
		case 1: return  __kernel_cosf(y[0],y[1]);
		case 2: return -__kernel_sinf(y[0],y[1],1);
		default:
			return -__kernel_cosf(y[0],y[1]);
	    }
	}
}
weak_alias (__sinf, sinf)