Sophiar2/src/third_party/base64.h

#ifndef _MACARON_BASE64_H_
#define _MACARON_BASE64_H_

/**
 * The MIT License (MIT)
 * Copyright (c) 2016 tomykaira
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <string_view>

namespace macaron {

    class Base64 {
    public:

        static size_t Encode(std::string_view data, char *p) {
            static constexpr char sEncodingTable[] = {
                    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
                    'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
                    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
                    'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
                    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
                    'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
                    'w', 'x', 'y', 'z', '0', '1', '2', '3',
                    '4', '5', '6', '7', '8', '9', '+', '/'
            };

            size_t in_len = data.size();
            size_t out_len = 4 * ((in_len + 2) / 3);

            if (p == nullptr) return out_len;

            size_t i;
            for (i = 0; i < in_len - 2; i += 3) {
                *p++ = sEncodingTable[(data[i] >> 2) & 0x3F];
                *p++ = sEncodingTable[((data[i] & 0x3) << 4) | ((int) (data[i + 1] & 0xF0) >> 4)];
                *p++ = sEncodingTable[((data[i + 1] & 0xF) << 2) | ((int) (data[i + 2] & 0xC0) >> 6)];
                *p++ = sEncodingTable[data[i + 2] & 0x3F];
            }
            if (i < in_len) {
                *p++ = sEncodingTable[(data[i] >> 2) & 0x3F];
                if (i == (in_len - 1)) {
                    *p++ = sEncodingTable[((data[i] & 0x3) << 4)];
                    *p++ = '=';
                } else {
                    *p++ = sEncodingTable[((data[i] & 0x3) << 4) | ((int) (data[i + 1] & 0xF0) >> 4)];
                    *p++ = sEncodingTable[((data[i + 1] & 0xF) << 2)];
                }
                *p++ = '=';
            }

            return out_len;
        }

        static size_t Decode(std::string_view input, char *out) {
            static constexpr unsigned char kDecodingTable[] = {
                    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
                    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
                    64, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
                    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 64, 64, 64, 64, 64,
                    64, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
                    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 64, 64, 64, 64, 64,
                    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
                    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64
            };

            size_t in_len = input.size();
            if (in_len % 4 != 0) return 0;

            size_t out_len = in_len / 4 * 3;
            if (input[in_len - 1] == '=') out_len--;
            if (input[in_len - 2] == '=') out_len--;

            if (out == nullptr) return out_len;

            for (size_t i = 0, j = 0; i < in_len;) {
                uint32_t a = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];
                uint32_t b = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];
                uint32_t c = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];
                uint32_t d = input[i] == '=' ? 0 & i++ : kDecodingTable[static_cast<int>(input[i++])];

                uint32_t triple = (a << 3 * 6) + (b << 2 * 6) + (c << 1 * 6) + (d << 0 * 6);

                if (j < out_len) out[j++] = (triple >> 2 * 8) & 0xFF;
                if (j < out_len) out[j++] = (triple >> 1 * 8) & 0xFF;
                if (j < out_len) out[j++] = (triple >> 0 * 8) & 0xFF;
            }

            return out_len;
        }

    };

}

#endif /* _MACARON_BASE64_H_ */