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 * ====================================================
16 #include <sys/cdefs.h>
17 __FBSDID("$FreeBSD$");
20 * __ieee754_fmodf(x,y)
21 * Return x mod y in exact arithmetic
22 * Method: shift and subtract
26 #include "math_private.h"
28 static const float one = 1.0, Zero[] = {0.0, -0.0,};
31 __ieee754_fmodf(float x, float y)
33 int32_t n,hx,hy,hz,ix,iy,sx,i;
37 sx = hx&0x80000000; /* sign of x */
39 hy &= 0x7fffffff; /* |y| */
41 /* purge off exception values */
42 if(hy==0||(hx>=0x7f800000)|| /* y=0,or x not finite */
43 (hy>0x7f800000)) /* or y is NaN */
45 if(hx<hy) return x; /* |x|<|y| return x */
47 return Zero[(u_int32_t)sx>>31]; /* |x|=|y| return x*0*/
49 /* determine ix = ilogb(x) */
50 if(hx<0x00800000) { /* subnormal x */
51 for (ix = -126,i=(hx<<8); i>0; i<<=1) ix -=1;
52 } else ix = (hx>>23)-127;
54 /* determine iy = ilogb(y) */
55 if(hy<0x00800000) { /* subnormal y */
56 for (iy = -126,i=(hy<<8); i>=0; i<<=1) iy -=1;
57 } else iy = (hy>>23)-127;
59 /* set up {hx,lx}, {hy,ly} and align y to x */
61 hx = 0x00800000|(0x007fffff&hx);
62 else { /* subnormal x, shift x to normal */
67 hy = 0x00800000|(0x007fffff&hy);
68 else { /* subnormal y, shift y to normal */
79 if(hz==0) /* return sign(x)*0 */
80 return Zero[(u_int32_t)sx>>31];
87 /* convert back to floating value and restore the sign */
88 if(hx==0) /* return sign(x)*0 */
89 return Zero[(u_int32_t)sx>>31];
90 while(hx<0x00800000) { /* normalize x */
94 if(iy>= -126) { /* normalize output */
95 hx = ((hx-0x00800000)|((iy+127)<<23));
96 SET_FLOAT_WORD(x,hx|sx);
97 } else { /* subnormal output */
100 SET_FLOAT_WORD(x,hx|sx);
101 x *= one; /* create necessary signal */
103 return x; /* exact output */