u64.c - 9base - revived minimalist port of Plan 9 userland to Unix
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u64.c (3267B)
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1 #include <lib9.h>
2
3 enum {
4 INVAL= 255
5 };
6
7 static uchar t64d[256] = {
8 INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
9 INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
10 INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, 62,INVAL,INVAL,INVAL, 63,
11 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
12 INVAL, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
13 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,INVAL,INVAL,INVAL,INVAL,INVAL,
14 INVAL, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
15 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,INVAL,INVAL,INVAL,INVAL,INVAL,
16 INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
17 INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
18 INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
19 INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
20 INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
21 INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
22 INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
23 INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL
24 };
25 static char t64e[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
26
27 int
28 dec64(uchar *out, int lim, char *in, int n)
29 {
30 ulong b24;
31 uchar *start = out;
32 uchar *e = out + lim;
33 int i, c;
34
35 b24 = 0;
36 i = 0;
37 while(n-- > 0){
38
39 c = t64d[*(uchar*)in++];
40 if(c == INVAL)
41 continue;
42 switch(i){
43 case 0:
44 b24 = c<<18;
45 break;
46 case 1:
47 b24 |= c<<12;
48 break;
49 case 2:
50 b24 |= c<<6;
51 break;
52 case 3:
53 if(out + 3 > e)
54 goto exhausted;
55
56 b24 |= c;
57 *out++ = b24>>16;
58 *out++ = b24>>8;
59 *out++ = b24;
60 i = -1;
61 break;
62 }
63 i++;
64 }
65 switch(i){
66 case 2:
67 if(out + 1 > e)
68 goto exhausted;
69 *out++ = b24>>16;
70 break;
71 case 3:
72 if(out + 2 > e)
73 goto exhausted;
74 *out++ = b24>>16;
75 *out++ = b24>>8;
76 break;
77 }
78 exhausted:
79 return out - start;
80 }
81
82 int
83 enc64(char *out, int lim, uchar *in, int n)
84 {
85 int i;
86 ulong b24;
87 char *start = out;
88 char *e = out + lim;
89
90 for(i = n/3; i > 0; i--){
91 b24 = (*in++)<<16;
92 b24 |= (*in++)<<8;
93 b24 |= *in++;
94 if(out + 4 >= e)
95 goto exhausted;
96 *out++ = t64e[(b24>>18)];
97 *out++ = t64e[(b24>>12)&0x3f];
98 *out++ = t64e[(b24>>6)&0x3f];
99 *out++ = t64e[(b24)&0x3f];
100 }
101
102 switch(n%3){
103 case 2:
104 b24 = (*in++)<<16;
105 b24 |= (*in)<<8;
106 if(out + 4 >= e)
107 goto exhausted;
108 *out++ = t64e[(b24>>18)];
109 *out++ = t64e[(b24>>12)&0x3f];
110 *out++ = t64e[(b24>>6)&0x3f];
111 *out++ = '=';
112 break;
113 case 1:
114 b24 = (*in)<<16;
115 if(out + 4 >= e)
116 goto exhausted;
117 *out++ = t64e[(b24>>18)];
118 *out++ = t64e[(b24>>12)&0x3f];
119 *out++ = '=';
120 *out++ = '=';
121 break;
122 }
123 exhausted:
124 *out = 0;
125 return out - start;
126 }