source: vendor/FreeBSD-msun/current/src/k_cosf.c

/* k_cosf.c -- float version of k_cos.c
 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
 */

/*
 * ====================================================
 * 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.
 * ====================================================
 */

#ifndef lint
static char rcsid[] = "$FreeBSD: src/lib/msun/src/k_cosf.c,v 1.7 2002/05/28 18:15:04 alfred Exp $";
#endif

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

static const float
one =  1.0000000000e+00, /* 0x3f800000 */
C1  =  4.1666667908e-02, /* 0x3d2aaaab */
C2  = -1.3888889225e-03, /* 0xbab60b61 */
C3  =  2.4801587642e-05, /* 0x37d00d01 */
C4  = -2.7557314297e-07, /* 0xb493f27c */
C5  =  2.0875723372e-09, /* 0x310f74f6 */
C6  = -1.1359647598e-11; /* 0xad47d74e */

float
__kernel_cosf(float x, float y)
{
        float a,hz,z,r,qx;
        int32_t ix;
        GET_FLOAT_WORD(ix,x);
        ix &= 0x7fffffff;                       /* ix = |x|'s high word*/
        if(ix<0x32000000) {                     /* if x < 2**27 */
            if(((int)x)==0) return one;         /* generate inexact */
        }
        z  = x*x;
        r  = z*(C1+z*(C2+z*(C3+z*(C4+z*(C5+z*C6)))));
        if(ix < 0x3e99999a)                     /* if |x| < 0.3 */
            return one - ((float)0.5*z - (z*r - x*y));
        else {
            if(ix > 0x3f480000) {               /* x > 0.78125 */
                qx = (float)0.28125;
            } else {
                SET_FLOAT_WORD(qx,ix-0x01000000);       /* x/4 */
            }
            hz = (float)0.5*z-qx;
            a  = one-qx;
            return a - (hz - (z*r-x*y));
        }
}