/src/moddable/xs/tools/fdlibm/e_fmod.c
Line | Count | Source (jump to first uncovered line) |
1 | | |
2 | | /* @(#)e_fmod.c 1.3 95/01/18 */ |
3 | | /* |
4 | | * ==================================================== |
5 | | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
6 | | * |
7 | | * Developed at SunSoft, a Sun Microsystems, Inc. business. |
8 | | * Permission to use, copy, modify, and distribute this |
9 | | * software is freely granted, provided that this notice |
10 | | * is preserved. |
11 | | * ==================================================== |
12 | | */ |
13 | | |
14 | | //__FBSDID("$FreeBSD: src/lib/msun/src/e_fmod.c,v 1.10 2008/02/22 02:30:34 das Exp $"); |
15 | | |
16 | | /* |
17 | | * __ieee754_fmod(x,y) |
18 | | * Return x mod y in exact arithmetic |
19 | | * Method: shift and subtract |
20 | | */ |
21 | | |
22 | | #include "math_private.h" |
23 | | |
24 | | static const double one = 1.0, Zero[] = {0.0, -0.0,}; |
25 | | |
26 | | double |
27 | | __ieee754_fmod(double x, double y) |
28 | 22.0M | { |
29 | 22.0M | int32_t n,hx,hy,hz,ix,iy,sx,i; |
30 | 22.0M | u_int32_t lx,ly,lz; |
31 | | |
32 | 22.0M | EXTRACT_WORDS(hx,lx,x); |
33 | 22.0M | EXTRACT_WORDS(hy,ly,y); |
34 | 22.0M | sx = hx&0x80000000; /* sign of x */ |
35 | 22.0M | hx ^=sx; /* |x| */ |
36 | 22.0M | hy &= 0x7fffffff; /* |y| */ |
37 | | |
38 | | /* purge off exception values */ |
39 | 22.0M | if((hy|ly)==0||(hx>=0x7ff00000)|| /* y=0,or x not finite */ |
40 | 22.0M | ((hy|((ly|-ly)>>31))>0x7ff00000)) /* or y is NaN */ |
41 | 758k | return (x*y)/(x*y); |
42 | 21.3M | if(hx<=hy) { |
43 | 4.10M | if((hx<hy)||(lx<ly)) return x; /* |x|<|y| return x */ |
44 | 133k | if(lx==ly) |
45 | 133k | return Zero[(u_int32_t)sx>>31]; /* |x|=|y| return x*0*/ |
46 | 133k | } |
47 | | |
48 | | /* determine ix = ilogb(x) */ |
49 | 17.2M | if(hx<0x00100000) { /* subnormal x */ |
50 | 0 | if(hx==0) { |
51 | 0 | for (ix = -1043, i=lx; i>0; i<<=1) ix -=1; |
52 | 0 | } else { |
53 | 0 | for (ix = -1022,i=(hx<<11); i>0; i<<=1) ix -=1; |
54 | 0 | } |
55 | 17.2M | } else ix = (hx>>20)-1023; |
56 | | |
57 | | /* determine iy = ilogb(y) */ |
58 | 17.2M | if(hy<0x00100000) { /* subnormal y */ |
59 | 37 | if(hy==0) { |
60 | 405 | for (iy = -1043, i=ly; i>0; i<<=1) iy -=1; |
61 | 24 | } else { |
62 | 135 | for (iy = -1022,i=(hy<<11); i>0; i<<=1) iy -=1; |
63 | 13 | } |
64 | 17.2M | } else iy = (hy>>20)-1023; |
65 | | |
66 | | /* set up {hx,lx}, {hy,ly} and align y to x */ |
67 | 17.2M | if(ix >= -1022) |
68 | 17.2M | hx = 0x00100000|(0x000fffff&hx); |
69 | 0 | else { /* subnormal x, shift x to normal */ |
70 | 0 | n = -1022-ix; |
71 | 0 | if(n<=31) { |
72 | 0 | hx = (hx<<n)|(lx>>(32-n)); |
73 | 0 | lx <<= n; |
74 | 0 | } else { |
75 | 0 | hx = lx<<(n-32); |
76 | 0 | lx = 0; |
77 | 0 | } |
78 | 0 | } |
79 | 17.2M | if(iy >= -1022) |
80 | 17.2M | hy = 0x00100000|(0x000fffff&hy); |
81 | 37 | else { /* subnormal y, shift y to normal */ |
82 | 37 | n = -1022-iy; |
83 | 37 | if(n<=31) { |
84 | 21 | hy = (hy<<n)|(ly>>(32-n)); |
85 | 21 | ly <<= n; |
86 | 21 | } else { |
87 | 16 | hy = ly<<(n-32); |
88 | 16 | ly = 0; |
89 | 16 | } |
90 | 37 | } |
91 | | |
92 | | /* fix point fmod */ |
93 | 17.2M | n = ix - iy; |
94 | 470M | while(n--) { |
95 | 456M | hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1; |
96 | 456M | if(hz<0){hx = hx+hx+(lx>>31); lx = lx+lx;} |
97 | 236M | else { |
98 | 236M | if((hz|lz)==0) /* return sign(x)*0 */ |
99 | 3.11M | return Zero[(u_int32_t)sx>>31]; |
100 | 232M | hx = hz+hz+(lz>>31); lx = lz+lz; |
101 | 232M | } |
102 | 456M | } |
103 | 14.0M | hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1; |
104 | 14.0M | if(hz>=0) {hx=hz;lx=lz;} |
105 | | |
106 | | /* convert back to floating value and restore the sign */ |
107 | 14.0M | if((hx|lx)==0) /* return sign(x)*0 */ |
108 | 1.67M | return Zero[(u_int32_t)sx>>31]; |
109 | 19.5M | while(hx<0x00100000) { /* normalize x */ |
110 | 7.10M | hx = hx+hx+(lx>>31); lx = lx+lx; |
111 | 7.10M | iy -= 1; |
112 | 7.10M | } |
113 | 12.4M | if(iy>= -1022) { /* normalize output */ |
114 | 12.4M | hx = ((hx-0x00100000)|((iy+1023)<<20)); |
115 | 12.4M | INSERT_WORDS(x,hx|sx,lx); |
116 | 12.4M | } else { /* subnormal output */ |
117 | 34 | n = -1022 - iy; |
118 | 34 | if(n<=20) { |
119 | 13 | lx = (lx>>n)|((u_int32_t)hx<<(32-n)); |
120 | 13 | hx >>= n; |
121 | 21 | } else if (n<=31) { |
122 | 6 | lx = (hx<<(32-n))|(lx>>n); hx = sx; |
123 | 15 | } else { |
124 | 15 | lx = hx>>(n-32); hx = sx; |
125 | 15 | } |
126 | 34 | INSERT_WORDS(x,hx|sx,lx); |
127 | 34 | x *= one; /* create necessary signal */ |
128 | 34 | } |
129 | 12.4M | return x; /* exact output */ |
130 | 14.0M | } |