penpen/b64
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

first commit

Browse source
This commit is contained in:
Eric 2025-05-26 00:06:22 +02:00
commit 9b1fe95a8e
7 changed files with 234 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

97
trans.c Normal file
View file

@ -0,0 +1,97 @@
#include "trans.h"
#define PADDING '='
unsigned char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
"abcdefghijklmnopqrstuvwxyz" \
"0123456789" \
"+/";
unsigned char *
encode(unsigned char *op, int np)
{
extern unsigned char s[];
unsigned char *sp;
int n;
sp = s;
switch (np) {
case 3:
*sp++ = b64[(*op & ~3) >> 2];
n = (*op++ & 3) << 4;
*sp++ = b64[n + ((*op & ~15) >> 4)];
n = (*op++ & 15) << 2;
*sp++ = b64[n + ((*op & 192) >> 6)];
*sp = b64[*op & ~192];
break;
case 2:
*sp++ = b64[(*op & ~3) >> 2];
n = (*op++ & 3) << 4;
*sp++ = b64[n + ((*op & ~15) >> 4)];
*sp++ = b64[(*op & 15) << 2];
*sp = PADDING;
break;
case 1:
*sp++ = b64[(*op & ~3) >> 2];
*sp++ = b64[(*op & 3) << 4];
*sp++ = PADDING;
*sp = PADDING;
break;
}
return s;
}
unsigned char *
decode(unsigned char *sp, int *np)
{
extern unsigned char o[];
unsigned char *op;
int n, b, atob(int c);
op = o;
switch (*np) {
case 4:
n = atob(*sp++) << 2;
b = atob(*sp++);
*op++ = n + ((b & ~15) >> 4);
n = (b & 15) << 4;
b = atob(*sp++);
*op++ = n + ((b & ~3) >> 2);
*op = ((b & 3) << 6) + atob(*sp);
break;
case 3:
n = atob(*sp++) << 2;
b = atob(*sp++);
*op++ = n + ((b & ~15) >> 4);
n = (b & 15) << 4;
*op = n + ((atob(*sp) & ~3) >> 2);
break;
case 2:
n = atob(*sp++) << 2;
*op = n + ((atob(*sp) & ~15) >> 4);
break;
}
*np = op-o+1;
return o;
}
int atob(int c)
{
if (c >= 'A' && c <= 'Z')
c -= 'A';
else if (c >= 'a' && c <= 'z')
c = c - 'a' + 26;
else if (c >= '0' && c <= '9')
c = c - '0' + 26 * 2;
else if (c == '+')
c = 62;
else
c = 63;
return c;
}