1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
|
#include <u.h>
#include <libc.h>
#include <bio.h>
#define ptsiz (sizeof(pt)/sizeof(pt[0]))
#define whsiz (sizeof(wheel)/sizeof(wheel[0]))
#define tabsiz (sizeof(table)/sizeof(table[0]))
#define tsiz8 (tabsiz*8)
double big = 9.007199254740992e15;
int pt[] =
{
2, 3, 5, 7, 11, 13, 17, 19, 23, 29,
31, 37, 41, 43, 47, 53, 59, 61, 67, 71,
73, 79, 83, 89, 97,101,103,107,109,113,
127,131,137,139,149,151,157,163,167,173,
179,181,191,193,197,199,211,223,227,229,
};
double wheel[] =
{
10, 2, 4, 2, 4, 6, 2, 6, 4, 2,
4, 6, 6, 2, 6, 4, 2, 6, 4, 6,
8, 4, 2, 4, 2, 4, 8, 6, 4, 6,
2, 4, 6, 2, 6, 6, 4, 2, 4, 6,
2, 6, 4, 2, 4, 2,10, 2,
};
uchar table[1000];
uchar bittab[] =
{
1, 2, 4, 8, 16, 32, 64, 128,
};
void mark(double nn, long k);
void ouch(void);
Biobuf bout;
void
main(int argc, char *argp[])
{
int i;
double k, temp, v, limit, nn;
Binit(&bout, 1, OWRITE);
if(argc <= 1) {
fprint(2, "usage: primes starting [ending]\n");
exits("usage");
}
nn = atof(argp[1]);
limit = big;
if(argc > 2) {
limit = atof(argp[2]);
if(limit < nn)
exits(0);
if(limit > big)
ouch();
}
if(nn < 0 || nn > big)
ouch();
if(nn == 0)
nn = 1;
if(nn < 230) {
for(i=0; i<ptsiz; i++) {
if(pt[i] < nn)
continue;
if(pt[i] > limit)
exits(0);
print("%d\n", pt[i]);
if(limit >= big)
exits(0);
}
nn = 230;
}
modf(nn/2, &temp);
nn = 2.*temp + 1;
/*
* clear the sieve table.
*/
for(;;) {
for(i=0; i<tabsiz; i++)
table[i] = 0;
/*
* run the sieve.
*/
v = sqrt(nn+tsiz8);
mark(nn, 3);
mark(nn, 5);
mark(nn, 7);
for(i=0,k=11; k<=v; k+=wheel[i]) {
mark(nn, k);
i++;
if(i >= whsiz)
i = 0;
}
/*
* now get the primes from the table
* and print them.
*/
for(i=0; i<tsiz8; i+=2) {
if(table[i>>3] & bittab[i&07])
continue;
temp = nn + i;
if(temp > limit)
exits(0);
Bprint(&bout, "%lld\n", (long long)temp);
if(limit >= big)
exits(0);
}
nn += tsiz8;
}
}
void
mark(double nn, long k)
{
double t1;
long j;
modf(nn/k, &t1);
j = k*t1 - nn;
if(j < 0)
j += k;
for(; j<tsiz8; j+=k)
table[j>>3] |= bittab[j&07];
}
void
ouch(void)
{
fprint(2, "limits exceeded\n");
exits("limits");
}
|