1 /* e_fmodf.c -- float version of e_fmod.c.
2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
4 * $FreeBSD: src/lib/msun/src/e_fmodf.c,v 1.5 1999/08/28 00:06:30 peter Exp $
5 * $DragonFly: src/lib/msun/src/Attic/e_fmodf.c,v 1.2 2003/06/17 04:26:52 dillon Exp $
9 * ====================================================
10 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
12 * Developed at SunPro, a Sun Microsystems, Inc. business.
13 * Permission to use, copy, modify, and distribute this
14 * software is freely granted, provided that this notice
16 * ====================================================
20 * __ieee754_fmodf(x,y)
21 * Return x mod y in exact arithmetic
22 * Method: shift and subtract
26 #include "math_private.h"
29 static const float one = 1.0, Zero[] = {0.0, -0.0,};
31 static float one = 1.0, Zero[] = {0.0, -0.0,};
35 float __ieee754_fmodf(float x, float y)
37 float __ieee754_fmodf(x,y)
41 int32_t n,hx,hy,hz,ix,iy,sx,i;
45 sx = hx&0x80000000; /* sign of x */
47 hy &= 0x7fffffff; /* |y| */
49 /* purge off exception values */
50 if(hy==0||(hx>=0x7f800000)|| /* y=0,or x not finite */
51 (hy>0x7f800000)) /* or y is NaN */
53 if(hx<hy) return x; /* |x|<|y| return x */
55 return Zero[(u_int32_t)sx>>31]; /* |x|=|y| return x*0*/
57 /* determine ix = ilogb(x) */
58 if(hx<0x00800000) { /* subnormal x */
59 for (ix = -126,i=(hx<<8); i>0; i<<=1) ix -=1;
60 } else ix = (hx>>23)-127;
62 /* determine iy = ilogb(y) */
63 if(hy<0x00800000) { /* subnormal y */
64 for (iy = -126,i=(hy<<8); i>=0; i<<=1) iy -=1;
65 } else iy = (hy>>23)-127;
67 /* set up {hx,lx}, {hy,ly} and align y to x */
69 hx = 0x00800000|(0x007fffff&hx);
70 else { /* subnormal x, shift x to normal */
75 hy = 0x00800000|(0x007fffff&hy);
76 else { /* subnormal y, shift y to normal */
87 if(hz==0) /* return sign(x)*0 */
88 return Zero[(u_int32_t)sx>>31];
95 /* convert back to floating value and restore the sign */
96 if(hx==0) /* return sign(x)*0 */
97 return Zero[(u_int32_t)sx>>31];
98 while(hx<0x00800000) { /* normalize x */
102 if(iy>= -126) { /* normalize output */
103 hx = ((hx-0x00800000)|((iy+127)<<23));
104 SET_FLOAT_WORD(x,hx|sx);
105 } else { /* subnormal output */
108 SET_FLOAT_WORD(x,hx|sx);
109 x *= one; /* create necessary signal */
111 return x; /* exact output */