1 /* e_fmodf.c -- float version of e_fmod.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
6 * ====================================================
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
9 * Developed at SunPro, a Sun Microsystems, Inc. business.
10 * Permission to use, copy, modify, and distribute this
11 * software is freely granted, provided that this notice
13 * ====================================================
15 * $NetBSD: e_fmodf.c,v 1.7 2002/05/26 22:01:49 wiz Exp $
20 * Return x mod y in exact arithmetic
21 * Method: shift and subtract
25 #include "math_private.h"
27 static const float one = 1.0, Zero[] = {0.0, -0.0,};
30 fmodf(float x, float y)
32 int32_t n,hx,hy,hz,ix,iy,sx,i;
36 sx = hx&0x80000000; /* sign of x */
38 hy &= 0x7fffffff; /* |y| */
40 /* purge off exception values */
41 if(hy==0||(hx>=0x7f800000)|| /* y=0,or x not finite */
42 (hy>0x7f800000)) /* or y is NaN */
44 if(hx<hy) return x; /* |x|<|y| return x */
46 return Zero[(u_int32_t)sx>>31]; /* |x|=|y| return x*0*/
48 /* determine ix = ilogb(x) */
49 if(hx<0x00800000) { /* subnormal x */
50 for (ix = -126,i=(hx<<8); i>0; i<<=1) ix -=1;
51 } else ix = (hx>>23)-127;
53 /* determine iy = ilogb(y) */
54 if(hy<0x00800000) { /* subnormal y */
55 for (iy = -126,i=(hy<<8); i>=0; i<<=1) iy -=1;
56 } else iy = (hy>>23)-127;
58 /* set up {hx,lx}, {hy,ly} and align y to x */
60 hx = 0x00800000|(0x007fffff&hx);
61 else { /* subnormal x, shift x to normal */
66 hy = 0x00800000|(0x007fffff&hy);
67 else { /* subnormal y, shift y to normal */
78 if(hz==0) /* return sign(x)*0 */
79 return Zero[(u_int32_t)sx>>31];
86 /* convert back to floating value and restore the sign */
87 if(hx==0) /* return sign(x)*0 */
88 return Zero[(u_int32_t)sx>>31];
89 while(hx<0x00800000) { /* normalize x */
93 if(iy>= -126) { /* normalize output */
94 hx = ((hx-0x00800000)|((iy+127)<<23));
95 SET_FLOAT_WORD(x,hx|sx);
96 } else { /* subnormal output */
99 SET_FLOAT_WORD(x,hx|sx);
100 x *= one; /* create necessary signal */
102 return x; /* exact output */