OpenCores
URL https://opencores.org/ocsvn/or1k/or1k/trunk

Subversion Repositories or1k

[/] [or1k/] [trunk/] [linux/] [uClibc/] [libm/] [e_fmod.c] - Blame information for rev 1765

Details | Compare with Previous | View Log

Line No. Rev Author Line
1 1325 phoenix
/* @(#)e_fmod.c 5.1 93/09/24 */
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
#if defined(LIBM_SCCS) && !defined(lint)
14
static char rcsid[] = "$NetBSD: e_fmod.c,v 1.8 1995/05/10 20:45:07 jtc Exp $";
15
#endif
16
 
17
/*
18
 * __ieee754_fmod(x,y)
19
 * Return x mod y in exact arithmetic
20
 * Method: shift and subtract
21
 */
22
 
23
#include "math.h"
24
#include "math_private.h"
25
 
26
#ifdef __STDC__
27
static const double one = 1.0, Zero[] = {0.0, -0.0,};
28
#else
29
static double one = 1.0, Zero[] = {0.0, -0.0,};
30
#endif
31
 
32
#ifdef __STDC__
33
        double __ieee754_fmod(double x, double y)
34
#else
35
        double __ieee754_fmod(x,y)
36
        double x,y ;
37
#endif
38
{
39
        int32_t n,hx,hy,hz,ix,iy,sx,i;
40
        u_int32_t lx,ly,lz;
41
 
42
        EXTRACT_WORDS(hx,lx,x);
43
        EXTRACT_WORDS(hy,ly,y);
44
        sx = hx&0x80000000;             /* sign of x */
45
        hx ^=sx;                /* |x| */
46
        hy &= 0x7fffffff;       /* |y| */
47
 
48
    /* purge off exception values */
49
        if((hy|ly)==0||(hx>=0x7ff00000)||        /* y=0,or x not finite */
50
          ((hy|((ly|-ly)>>31))>0x7ff00000))     /* or y is NaN */
51
            return (x*y)/(x*y);
52
        if(hx<=hy) {
53
            if((hx<hy)||(lx<ly)) return x;      /* |x|<|y| return x */
54
            if(lx==ly)
55
                return Zero[(u_int32_t)sx>>31]; /* |x|=|y| return x*0*/
56
        }
57
 
58
    /* determine ix = ilogb(x) */
59
        if(hx<0x00100000) {     /* subnormal x */
60
            if(hx==0) {
61
                for (ix = -1043, i=lx; i>0; i<<=1) ix -=1;
62
            } else {
63
                for (ix = -1022,i=(hx<<11); i>0; i<<=1) ix -=1;
64
            }
65
        } else ix = (hx>>20)-1023;
66
 
67
    /* determine iy = ilogb(y) */
68
        if(hy<0x00100000) {     /* subnormal y */
69
            if(hy==0) {
70
                for (iy = -1043, i=ly; i>0; i<<=1) iy -=1;
71
            } else {
72
                for (iy = -1022,i=(hy<<11); i>0; i<<=1) iy -=1;
73
            }
74
        } else iy = (hy>>20)-1023;
75
 
76
    /* set up {hx,lx}, {hy,ly} and align y to x */
77
        if(ix >= -1022)
78
            hx = 0x00100000|(0x000fffff&hx);
79
        else {          /* subnormal x, shift x to normal */
80
            n = -1022-ix;
81
            if(n<=31) {
82
                hx = (hx<<n)|(lx>>(32-n));
83
                lx <<= n;
84
            } else {
85
                hx = lx<<(n-32);
86
                lx = 0;
87
            }
88
        }
89
        if(iy >= -1022)
90
            hy = 0x00100000|(0x000fffff&hy);
91
        else {          /* subnormal y, shift y to normal */
92
            n = -1022-iy;
93
            if(n<=31) {
94
                hy = (hy<<n)|(ly>>(32-n));
95
                ly <<= n;
96
            } else {
97
                hy = ly<<(n-32);
98
                ly = 0;
99
            }
100
        }
101
 
102
    /* fix point fmod */
103
        n = ix - iy;
104
        while(n--) {
105
            hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
106
            if(hz<0){hx = hx+hx+(lx>>31); lx = lx+lx;}
107
            else {
108
                if((hz|lz)==0)           /* return sign(x)*0 */
109
                    return Zero[(u_int32_t)sx>>31];
110
                hx = hz+hz+(lz>>31); lx = lz+lz;
111
            }
112
        }
113
        hz=hx-hy;lz=lx-ly; if(lx<ly) hz -= 1;
114
        if(hz>=0) {hx=hz;lx=lz;}
115
 
116
    /* convert back to floating value and restore the sign */
117
        if((hx|lx)==0)                   /* return sign(x)*0 */
118
            return Zero[(u_int32_t)sx>>31];
119
        while(hx<0x00100000) {          /* normalize x */
120
            hx = hx+hx+(lx>>31); lx = lx+lx;
121
            iy -= 1;
122
        }
123
        if(iy>= -1022) {        /* normalize output */
124
            hx = ((hx-0x00100000)|((iy+1023)<<20));
125
            INSERT_WORDS(x,hx|sx,lx);
126
        } else {                /* subnormal output */
127
            n = -1022 - iy;
128
            if(n<=20) {
129
                lx = (lx>>n)|((u_int32_t)hx<<(32-n));
130
                hx >>= n;
131
            } else if (n<=31) {
132
                lx = (hx<<(32-n))|(lx>>n); hx = sx;
133
            } else {
134
                lx = hx>>(n-32); hx = sx;
135
            }
136
            INSERT_WORDS(x,hx|sx,lx);
137
            x *= one;           /* create necessary signal */
138
        }
139
        return x;               /* exact output */
140
}

powered by: WebSVN 2.1.0

© copyright 1999-2024 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.