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#include <lib9.h>
enum {
INVAL= 255
};
static uchar t64d[256] = {
INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL, 62,INVAL,INVAL,INVAL, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL, 0, 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,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL, 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,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,
INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL,INVAL
};
static char t64e[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
int
dec64(uchar *out, int lim, char *in, int n)
{
ulong b24;
uchar *start = out;
uchar *e = out + lim;
int i, c;
b24 = 0;
i = 0;
while(n-- > 0){
c = t64d[*(uchar*)in++];
if(c == INVAL)
continue;
switch(i){
case 0:
b24 = c<<18;
break;
case 1:
b24 |= c<<12;
break;
case 2:
b24 |= c<<6;
break;
case 3:
if(out + 3 > e)
goto exhausted;
b24 |= c;
*out++ = b24>>16;
*out++ = b24>>8;
*out++ = b24;
i = -1;
break;
}
i++;
}
switch(i){
case 2:
if(out + 1 > e)
goto exhausted;
*out++ = b24>>16;
break;
case 3:
if(out + 2 > e)
goto exhausted;
*out++ = b24>>16;
*out++ = b24>>8;
break;
}
exhausted:
return out - start;
}
int
enc64(char *out, int lim, uchar *in, int n)
{
int i;
ulong b24;
char *start = out;
char *e = out + lim;
for(i = n/3; i > 0; i--){
b24 = (*in++)<<16;
b24 |= (*in++)<<8;
b24 |= *in++;
if(out + 4 >= e)
goto exhausted;
*out++ = t64e[(b24>>18)];
*out++ = t64e[(b24>>12)&0x3f];
*out++ = t64e[(b24>>6)&0x3f];
*out++ = t64e[(b24)&0x3f];
}
switch(n%3){
case 2:
b24 = (*in++)<<16;
b24 |= (*in)<<8;
if(out + 4 >= e)
goto exhausted;
*out++ = t64e[(b24>>18)];
*out++ = t64e[(b24>>12)&0x3f];
*out++ = t64e[(b24>>6)&0x3f];
*out++ = '=';
break;
case 1:
b24 = (*in)<<16;
if(out + 4 >= e)
goto exhausted;
*out++ = t64e[(b24>>18)];
*out++ = t64e[(b24>>12)&0x3f];
*out++ = '=';
*out++ = '=';
break;
}
exhausted:
*out = 0;
return out - start;
}
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