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/*
* phc -- the open source PHP compiler
* See doc/license/README.license for licensing information
*
* Base64 encoder/decoder. See RFC2045.
*/
#include "lib/String.h"
#include <iostream>
#include <sstream>
using namespace std;
static char enc_table[] =
"ABCDEFGHIJKLMNOPQ"
"RSTUVWXYZabcdefgh"
"ijklmnopqrstuvwxy"
"z0123456789+/";
// Reverse of the enc_table
// Return 0xFF for padding bytes
unsigned char decode(unsigned char c)
{
if(c >= 'A' && c <= 'Z')
return c - 'A';
if(c >= 'a' && c <= 'z')
return c - 'a' + 26;
if(c >= '0' && c <= '9')
return c - '0' + 26 + 26;
if(c == '+')
return 26 + 26 + 10;
if(c == '/')
return 26 + 26 + 10 + 1;
if(c == '=')
return 0xFF;
assert(false);
return 0;
}
#define TRIPLE_TO_QUAD \
a = (x & 0xFC) >> 2; \
b = ((x & 0x03) << 4) | ((y & 0xF0) >> 4); \
c = ((y & 0x0F) << 2) | ((z & 0xC0) >> 6); \
d = z & 0x3F;
#define QUAD_TO_TRIPLE \
x = (a << 2) | ((b & 0x30) >> 4); \
y = ((b & 0x0F) << 4) | ((c & 0x3C) >> 2); \
z = ((c & 0x03) << 6) | d;
String* base64_encode(String* str)
{
String::const_iterator i = str->begin();
ostringstream os;
unsigned char x, y, z;
unsigned char a, b, c, d;
while(i != str->end())
{
x = *i++;
if(i == str->end())
{
// Two padding bytes
y = 0;
z = 0;
TRIPLE_TO_QUAD;
os << enc_table[a];
os << enc_table[b];
os << '=';
os << '=';
break;
}
y = *i++;
if(i == str->end())
{
// One padding byte
z = 0;
TRIPLE_TO_QUAD;
os << enc_table[a];
os << enc_table[b];
os << enc_table[c];
os << '=';
break;
}
z = *i++;
TRIPLE_TO_QUAD;
os << enc_table[a];
os << enc_table[b];
os << enc_table[c];
os << enc_table[d];
}
return new String(os.str());
}
String* base64_decode(String* str)
{
String::const_iterator i = str->begin();
ostringstream os;
unsigned char x, y, z;
unsigned char a, b, c, d;
while(i != str->end())
{
a = decode(*i++);
b = decode(*i++);
c = decode(*i++);
d = decode(*i++);
if(c == 0xFF)
{
// Two padding bytes
QUAD_TO_TRIPLE;
os << x;
break;
}
if(d == 0xFF)
{
// One padding byte
QUAD_TO_TRIPLE;
os << x << y;
break;
}
QUAD_TO_TRIPLE;
os << x << y << z;
}
return new String(os.str());
}
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