Base64.hpp

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#pragma once
 
#include <vector>
#include <string>
 
static std::string base64Encode(const std::string &in) {
 
  std::string out;
 
  int val = 0, valb = -6;
  for (std::uint8_t c: in) {
    val = (val << 8) + c;
    valb += 8;
    while (valb >= 0) {
      out.push_back("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"[(val >> valb) & 0x3F]);
      valb -= 6;
    }
  }
  if (valb > -6) out.push_back("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"[((val << 8) >> (valb + 8)) & 0x3F]);
  while (out.size() % 4) out.push_back('=');
  return out;
}
 
static std::string base64Decode(const std::string &in) {
 
  std::string out;
 
  std::vector<int> T(256, -1);
  for (int i = 0; i < 64; i++) T["ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"[i]] = i;
 
  int val = 0, valb = -8;
  for (std::uint8_t c: in) {
    if (T[c] == -1) break;
    val = (val << 6) + T[c];
    valb += 6;
    if (valb >= 0) {
      out.push_back(char((val >> valb) & 0xFF));
      valb -= 8;
    }
  }
  return out;
}