1#include "SDL_internal.h"
2/*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5 *
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
11 */
12
13/*
14 * __ieee754_fmod(x,y)
15 * Return x mod y in exact arithmetic
16 * Method: shift and subtract
17 */
18
19#include "math_libm.h"
20#include "math_private.h"
21
22static const double one = 1.0, Zero[] = {0.0, -0.0,};
23
24double attribute_hidden __ieee754_fmod(double x, double y)
25{
26 int32_t n,hx,hy,hz,ix,iy,sx,i;
27 u_int32_t lx,ly,lz;
28
29 EXTRACT_WORDS(hx,lx,x);
30 EXTRACT_WORDS(hy,ly,y);
31 sx = hx&0x80000000; /* sign of x */
32 hx ^=sx; /* |x| */
33 hy &= 0x7fffffff; /* |y| */
34
35 /* purge off exception values */
36 if((hy|ly)==0||(hx>=0x7ff00000)|| /* y=0,or x not finite */
37 ((hy|((ly|-(int32_t)ly)>>31))>0x7ff00000)) /* or y is NaN */
38 return (x*y)/(x*y);
39 if(hx<=hy) {
40 if((hx<hy)||(lx<ly)) return x; /* |x|<|y| return x */
41 if(lx==ly)
42 return Zero[(u_int32_t)sx>>31]; /* |x|=|y| return x*0*/
43 }
44
45 /* determine ix = ilogb(x) */
46 if(hx<0x00100000) { /* subnormal x */
47 if(hx==0) {
48 for (ix = -1043, i=lx; i>0; i<<=1) ix -=1;
49 } else {
50 for (ix = -1022,i=(hx<<11); i>0; i<<=1) ix -=1;
51 }
52 } else ix = (hx>>20)-1023;
53
54 /* determine iy = ilogb(y) */
55 if(hy<0x00100000) { /* subnormal y */
56 if(hy==0) {
57 for (iy = -1043, i=ly; i>0; i<<=1) iy -=1;
58 } else {
59 for (iy = -1022,i=(hy<<11); i>0; i<<=1) iy -=1;
60 }
61 } else iy = (hy>>20)-1023;
62
63 /* set up {hx,lx}, {hy,ly} and align y to x */
64 if(ix >= -1022)
65 hx = 0x00100000|(0x000fffff&hx);
66 else { /* subnormal x, shift x to normal */
67 n = -1022-ix;
68 if(n<=31) {
69 hx = (hx<<n)|(lx>>(32-n));
70 lx <<= n;
71 } else {
72 hx = lx<<(n-32);
73 lx = 0;
74 }
75 }
76 if(iy >= -1022)
77 hy = 0x00100000|(0x000fffff&hy);
78 else { /* subnormal y, shift y to normal */
79 n = -1022-iy;
80 if(n<=31) {
81 hy = (hy<<n)|(ly>>(32-n));
82 ly <<= n;
83 } else {
84 hy = ly<<(n-32);
85 ly = 0;
86 }
87 }
88
89 /* fix point fmod */
90 n = ix - iy;
91 while(n--) {
92 hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
93 if(hz<0){hx = hx+hx+(lx>>31); lx = lx+lx;}
94 else {
95 if((hz|lz)==0) /* return sign(x)*0 */
96 return Zero[(u_int32_t)sx>>31];
97 hx = hz+hz+(lz>>31); lx = lz+lz;
98 }
99 }
100 hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
101 if(hz>=0) {hx=hz;lx=lz;}
102
103 /* convert back to floating value and restore the sign */
104 if((hx|lx)==0) /* return sign(x)*0 */
105 return Zero[(u_int32_t)sx>>31];
106 while(hx<0x00100000) { /* normalize x */
107 hx = hx+hx+(lx>>31); lx = lx+lx;
108 iy -= 1;
109 }
110 if(iy>= -1022) { /* normalize output */
111 hx = ((hx-0x00100000)|((iy+1023)<<20));
112 INSERT_WORDS(x,hx|sx,lx);
113 } else { /* subnormal output */
114 n = -1022 - iy;
115 if(n<=20) {
116 lx = (lx>>n)|((u_int32_t)hx<<(32-n));
117 hx >>= n;
118 } else if (n<=31) {
119 lx = (hx<<(32-n))|(lx>>n); hx = sx;
120 } else {
121 lx = hx>>(n-32); hx = sx;
122 }
123 INSERT_WORDS(x,hx|sx,lx);
124 x *= one; /* create necessary signal */
125 }
126 return x; /* exact output */
127}
128
129/*
130 * wrapper fmod(x,y)
131 */
132#ifndef _IEEE_LIBM
133double fmod(double x, double y)
134{
135 double z = __ieee754_fmod(x, y);
136 if (_LIB_VERSION == _IEEE_ || isnan(y) || isnan(x))
137 return z;
138 if (y == 0.0)
139 return __kernel_standard(x, y, 27); /* fmod(x,0) */
140 return z;
141}
142#else
143strong_alias(__ieee754_fmod, fmod)
144#endif
145libm_hidden_def(fmod)
146