llamapi.cpp/base64.h at master · poisson-fish/llamapi.cpp · GitHub

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/**
 * @file base64.h
 * @author Basit Ayantunde (rlamarrr@gmail.com)
 * @brief
 * @version 0.1
 * @date 2019-09-08
 *
 * @copyright Copyright (c) 2019
 *
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0

 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#ifndef LAMAR_BASE64_H
#define LAMAR_BASE64_H
#include <cstring>
#include <string>

namespace base64 {

template <typename T = char>
struct Base64Chars {
  static constexpr T data[] =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
      "abcdefghijklmnopqrstuvwxyz"
      "0123456789+/";
};

template <typename T = char>
inline bool is_base64(T c) {
  return (isalnum(c) || (c == '+') || (c == '/'));
}

template <typename T = char>
std::basic_string<T> encode(const T* bytes_to_encode, uint32_t in_len) {
  std::basic_string<T> ret;
  int i = 0;
  int j = 0;
  T char_array_3[3];
  T char_array_4[4];

  while (in_len--) {
    char_array_3[i++] = *(bytes_to_encode++);
    if (i == 3) {
      char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
      char_array_4[1] =
          ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
      char_array_4[2] =
          ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
      char_array_4[3] = char_array_3[2] & 0x3f;

      for (i = 0; (i < 4); i++) ret += Base64Chars<T>::data[char_array_4[i]];
      i = 0;
    }
  }

  if (i) {
    for (j = i; j < 3; j++) char_array_3[j] = '\0';

    char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
    char_array_4[1] =
        ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
    char_array_4[2] =
        ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
    char_array_4[3] = char_array_3[2] & 0x3f;

    for (j = 0; (j < i + 1); j++) ret += Base64Chars<T>::data[char_array_4[j]];

    while ((i++ < 3)) ret += '=';
  }

  return std::move(ret);
}

template <typename T = char>
std::basic_string<T> decode(const T* encoded_string, int64_t in_len) {
  int i = 0;
  int j = 0;
  int in_ = 0;
  T char_array_4[4], char_array_3[3];
  std::basic_string<T> ret;

  while (in_len-- && (encoded_string[in_] != '=') &&
         is_base64(encoded_string[in_])) {
    char_array_4[i++] = encoded_string[in_];
    in_++;
    if (i == 4) {
      for (i = 0; i < 4; i++)
        char_array_4[i] = strchr(Base64Chars<T>::data, char_array_4[i]) -
                          Base64Chars<T>::data;

      char_array_3[0] =
          (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
      char_array_3[1] =
          ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
      char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

      for (i = 0; (i < 3); i++) ret += char_array_3[i];
      i = 0;
    }
  }

  if (i) {
    for (j = i; j < 4; j++) char_array_4[j] = 0;

    for (j = 0; j < 4; j++)
      char_array_4[j] =
          strchr(Base64Chars<T>::data, char_array_4[j]) - Base64Chars<T>::data;

    char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
    char_array_3[1] =
        ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
    char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];

    for (j = 0; (j < i - 1); j++) ret += char_array_3[j];
  }

  return std::move(ret);
}

};  // namespace base64

#endif