1 #include <lib9.h>
2 
3 int
4 dec32(uchar *dest, int ndest, char *src, int nsrc)
5 {
6 	char *s, *tab;
7 	uchar *start;
8 	int i, u[8];
9 
10 	if(ndest+1 < (5*nsrc+7)/8)
11 		return -1;
12 	start = dest;
13 	tab = "23456789abcdefghijkmnpqrstuvwxyz";
14 	while(nsrc>=8){
15 		for(i=0; i<8; i++){
16 			s = strchr(tab,(int)src[i]);
17 			u[i] = s ? s-tab : 0;
18 		}
19 		*dest++ = (u[0]<<3) | (0x7 & (u[1]>>2));
20 		*dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4));
21 		*dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1));
22 		*dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3));
23 		*dest++ = ((0x7 & u[6])<<5) | u[7];
24 		src  += 8;
25 		nsrc -= 8;
26 	}
27 	if(nsrc > 0){
28 		if(nsrc == 1 || nsrc == 3 || nsrc == 6)
29 			return -1;
30 		for(i=0; i<nsrc; i++){
31 			s = strchr(tab,(int)src[i]);
32 			u[i] = s ? s-tab : 0;
33 		}
34 		*dest++ = (u[0]<<3) | (0x7 & (u[1]>>2));
35 		if(nsrc == 2)
36 			goto out;
37 		*dest++ = ((0x3 & u[1])<<6) | (u[2]<<1) | (0x1 & (u[3]>>4));
38 		if(nsrc == 4)
39 			goto out;
40 		*dest++ = ((0xf & u[3])<<4) | (0xf & (u[4]>>1));
41 		if(nsrc == 5)
42 			goto out;
43 		*dest++ = ((0x1 & u[4])<<7) | (u[5]<<2) | (0x3 & (u[6]>>3));
44 	}
45 out:
46 	return dest-start;
47 }
48 
49 int
50 enc32(char *dest, int ndest, uchar *src, int nsrc)
51 {
52 	char *tab, *start;
53 	int j;
54 
55 	if(ndest <= (8*nsrc+4)/5 )
56 		return -1;
57 	start = dest;
58 	tab = "23456789abcdefghijkmnpqrstuvwxyz";
59 	while(nsrc>=5){
60 		j = (0x1f & (src[0]>>3));
61 		*dest++ = tab[j];
62 		j = (0x1c & (src[0]<<2)) | (0x03 & (src[1]>>6));
63 		*dest++ = tab[j];
64 		j = (0x1f & (src[1]>>1));
65 		*dest++ = tab[j];
66 		j = (0x10 & (src[1]<<4)) | (0x0f & (src[2]>>4));
67 		*dest++ = tab[j];
68 		j = (0x1e & (src[2]<<1)) | (0x01 & (src[3]>>7));
69 		*dest++ = tab[j];
70 		j = (0x1f & (src[3]>>2));
71 		*dest++ = tab[j];
72 		j = (0x18 & (src[3]<<3)) | (0x07 & (src[4]>>5));
73 		*dest++ = tab[j];
74 		j = (0x1f & (src[4]));
75 		*dest++ = tab[j];
76 		src  += 5;
77 		nsrc -= 5;
78 	}
79 	if(nsrc){
80 		j = (0x1f & (src[0]>>3));
81 		*dest++ = tab[j];
82 		j = (0x1c & (src[0]<<2));
83 		if(nsrc == 1)
84 			goto out;
85 		j |= (0x03 & (src[1]>>6));
86 		*dest++ = tab[j];
87 		j = (0x1f & (src[1]>>1));
88 		if(nsrc == 2)
89 			goto out;
90 		*dest++ = tab[j];
91 		j = (0x10 & (src[1]<<4));
92 		if(nsrc == 3)
93 			goto out;
94 		j |= (0x0f & (src[2]>>4));
95 		*dest++ = tab[j];
96 		j = (0x1e & (src[2]<<1));
97 		if(nsrc == 4)
98 			goto out;
99 		j |= (0x01 & (src[3]>>7));
100 		*dest++ = tab[j];
101 		j = (0x1f & (src[3]>>2));
102 		*dest++ = tab[j];
103 		j = (0x18 & (src[3]<<3));
104 out:
105 		*dest++ = tab[j];
106 	}
107 	*dest = 0;
108 	return dest-start;
109 }