1 | /* e_fmodl.c -- long double version of e_fmod.c. |
2 | * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz. |
3 | */ |
4 | /* |
5 | * ==================================================== |
6 | * Copyright (C) 1993, 2011 by Sun Microsystems, Inc. All rights reserved. |
7 | * |
8 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
9 | * Permission to use, copy, modify, and distribute this |
10 | * software is freely granted, provided that this notice |
11 | * is preserved. |
12 | * ==================================================== |
13 | */ |
14 | |
15 | /* |
16 | * __ieee754_fmodl(x,y) |
17 | * Return x mod y in exact arithmetic |
18 | * Method: shift and subtract |
19 | */ |
20 | |
21 | #include <math.h> |
22 | #include <math_private.h> |
23 | #include <libm-alias-finite.h> |
24 | |
25 | static const _Float128 one = 1.0, Zero[] = {0.0, -0.0,}; |
26 | |
27 | _Float128 |
28 | __ieee754_fmodl (_Float128 x, _Float128 y) |
29 | { |
30 | int64_t n,hx,hy,hz,ix,iy,sx,i; |
31 | uint64_t lx,ly,lz; |
32 | |
33 | GET_LDOUBLE_WORDS64(hx,lx,x); |
34 | GET_LDOUBLE_WORDS64(hy,ly,y); |
35 | sx = hx&0x8000000000000000ULL; /* sign of x */ |
36 | hx ^=sx; /* |x| */ |
37 | hy &= 0x7fffffffffffffffLL; /* |y| */ |
38 | |
39 | /* purge off exception values */ |
40 | if((hy|ly)==0||(hx>=0x7fff000000000000LL)|| /* y=0,or x not finite */ |
41 | ((hy|((ly|-ly)>>63))>0x7fff000000000000LL)) /* or y is NaN */ |
42 | return (x*y)/(x*y); |
43 | if(hx<=hy) { |
44 | if((hx<hy)||(lx<ly)) return x; /* |x|<|y| return x */ |
45 | if(lx==ly) |
46 | return Zero[(uint64_t)sx>>63]; /* |x|=|y| return x*0*/ |
47 | } |
48 | |
49 | /* determine ix = ilogb(x) */ |
50 | if(hx<0x0001000000000000LL) { /* subnormal x */ |
51 | if(hx==0) { |
52 | for (ix = -16431, i=lx; i>0; i<<=1) ix -=1; |
53 | } else { |
54 | for (ix = -16382, i=hx<<15; i>0; i<<=1) ix -=1; |
55 | } |
56 | } else ix = (hx>>48)-0x3fff; |
57 | |
58 | /* determine iy = ilogb(y) */ |
59 | if(hy<0x0001000000000000LL) { /* subnormal y */ |
60 | if(hy==0) { |
61 | for (iy = -16431, i=ly; i>0; i<<=1) iy -=1; |
62 | } else { |
63 | for (iy = -16382, i=hy<<15; i>0; i<<=1) iy -=1; |
64 | } |
65 | } else iy = (hy>>48)-0x3fff; |
66 | |
67 | /* set up {hx,lx}, {hy,ly} and align y to x */ |
68 | if(ix >= -16382) |
69 | hx = 0x0001000000000000LL|(0x0000ffffffffffffLL&hx); |
70 | else { /* subnormal x, shift x to normal */ |
71 | n = -16382-ix; |
72 | if(n<=63) { |
73 | hx = (hx<<n)|(lx>>(64-n)); |
74 | lx <<= n; |
75 | } else { |
76 | hx = lx<<(n-64); |
77 | lx = 0; |
78 | } |
79 | } |
80 | if(iy >= -16382) |
81 | hy = 0x0001000000000000LL|(0x0000ffffffffffffLL&hy); |
82 | else { /* subnormal y, shift y to normal */ |
83 | n = -16382-iy; |
84 | if(n<=63) { |
85 | hy = (hy<<n)|(ly>>(64-n)); |
86 | ly <<= n; |
87 | } else { |
88 | hy = ly<<(n-64); |
89 | ly = 0; |
90 | } |
91 | } |
92 | |
93 | /* fix point fmod */ |
94 | n = ix - iy; |
95 | while(n--) { |
96 | hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1; |
97 | if(hz<0){hx = hx+hx+(lx>>63); lx = lx+lx;} |
98 | else { |
99 | if((hz|lz)==0) /* return sign(x)*0 */ |
100 | return Zero[(uint64_t)sx>>63]; |
101 | hx = hz+hz+(lz>>63); lx = lz+lz; |
102 | } |
103 | } |
104 | hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1; |
105 | if(hz>=0) {hx=hz;lx=lz;} |
106 | |
107 | /* convert back to floating value and restore the sign */ |
108 | if((hx|lx)==0) /* return sign(x)*0 */ |
109 | return Zero[(uint64_t)sx>>63]; |
110 | while(hx<0x0001000000000000LL) { /* normalize x */ |
111 | hx = hx+hx+(lx>>63); lx = lx+lx; |
112 | iy -= 1; |
113 | } |
114 | if(iy>= -16382) { /* normalize output */ |
115 | hx = ((hx-0x0001000000000000LL)|((iy+16383)<<48)); |
116 | SET_LDOUBLE_WORDS64(x,hx|sx,lx); |
117 | } else { /* subnormal output */ |
118 | n = -16382 - iy; |
119 | if(n<=48) { |
120 | lx = (lx>>n)|((uint64_t)hx<<(64-n)); |
121 | hx >>= n; |
122 | } else if (n<=63) { |
123 | lx = (hx<<(64-n))|(lx>>n); hx = sx; |
124 | } else { |
125 | lx = hx>>(n-64); hx = sx; |
126 | } |
127 | SET_LDOUBLE_WORDS64(x,hx|sx,lx); |
128 | x *= one; /* create necessary signal */ |
129 | } |
130 | return x; /* exact output */ |
131 | } |
132 | libm_alias_finite (__ieee754_fmodl, __fmodl) |
133 | |