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/*******************************************************************************
* librepfunc - a collection of common functions, classes and tools.
* See the README file for copyright information and how to reach the author.
******************************************************************************/
#include <array> // std::array
#include <repfunc.h>
std::string B64tbl("ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/");
std::array<uint8_t,4> get4x6(std::array<uint8_t,3> bytes) {
std::array<uint8_t,4> result;
result[0] = bytes[0] >> 2;
result[1] = ((bytes[0] & 3 ) << 4) | (bytes[1] >> 4);
result[2] = ((bytes[1] & 15) << 2) | (bytes[2] >> 6);
result[3] = bytes[2] & 0x3F;
return result;
}
std::array<uint8_t,3> get3x8(std::array<uint8_t,4> sx) {
std::array<uint8_t,3> result;
result[0] = (sx[0] << 2) | (sx[1] >> 4);
result[1] = ((sx[1] & 15) << 4) | ((sx[2] & 0x3C) >> 2);
result[2] = ((sx[2] & 3 ) << 6) | sx[3];
return result;
}
uint8_t getIdx(char c, std::string& alphabet) {
if (c == '=')
return 0;
return alphabet.find(c);
}
std::string ToBase64(std::vector<uint8_t>& bytes, std::string& alphabet) {
std::string result;
result.reserve((4*(bytes.size()+1))/3);
size_t len = bytes.size();
const uint8_t* buf = bytes.data();
while(len > 2) {
auto sx = get4x6({buf[0],buf[1],buf[2]});
result += alphabet[sx[0]];
result += alphabet[sx[1]];
result += alphabet[sx[2]];
result += alphabet[sx[3]];
len -= 3;
buf += 3;
}
if (len == 2) {
auto sx = get4x6({buf[0],buf[1],0});
result += alphabet[sx[0]];
result += alphabet[sx[1]];
result += alphabet[sx[2]];
result += "=";
}
else if (len == 1) {
auto sx = get4x6({buf[0],0,0});
result += alphabet[sx[0]];
result += alphabet[sx[1]];
result += "==";
}
return result;
}
std::string ToBase64(std::vector<uint8_t>& bytes) {
return ToBase64(bytes, B64tbl);
}
std::vector<uint8_t> FromBase64(std::string s, std::string& alphabet) {
std::vector<uint8_t> result;
result.reserve((3*(s.size()+1))/4);
size_t len = s.size();
const char* c = s.c_str();
while(len > 3) {
auto bytes = get3x8({getIdx(c[0],alphabet),
getIdx(c[1],alphabet),
getIdx(c[2],alphabet),
getIdx(c[3],alphabet)});
result.push_back(bytes[0]);
result.push_back(bytes[1]);
result.push_back(bytes[2]);
if (c[3] == '=') {
result.pop_back();
if (c[2] == '=')
result.pop_back();
break;
}
len -= 4;
c += 4;
}
if (len == 3) {
auto bytes = get3x8({getIdx(c[0],alphabet),
getIdx(c[1],alphabet),
getIdx(c[2],alphabet),
0});
result.push_back(bytes[0]);
result.push_back(bytes[1]);
}
else if (len == 2) {
auto bytes = get3x8({getIdx(c[0],alphabet),
getIdx(c[1],alphabet),
0,0});
result.push_back(bytes[0]);
}
return result;
}
std::vector<uint8_t> FromBase64(std::string s) {
return FromBase64(s, B64tbl);
}
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