| 7 | { |
| 8 | |
| 9 | std::vector<uint8_t> Decode( const std::string_view& str ) |
| 10 | { |
| 11 | std::vector<uint8_t> result; |
| 12 | result.reserve( ( str.size() / 4 ) * 3 ); |
| 13 | |
| 14 | auto Index = []( char p ) -> uint8_t { |
| 15 | if( p >= 'A' && p <= 'Z' ) |
| 16 | { |
| 17 | return p - 'A'; |
| 18 | } |
| 19 | else if( p >= 'a' && p <= 'z' ) |
| 20 | { |
| 21 | return p - 'a' + 26; |
| 22 | } |
| 23 | else if( p >= '0' && p <= '9' ) |
| 24 | { |
| 25 | return p - '0' + 52; |
| 26 | } |
| 27 | else if( p == '+' ) |
| 28 | { |
| 29 | return 62; |
| 30 | } |
| 31 | else if( p == '/' ) |
| 32 | { |
| 33 | return 63; |
| 34 | } |
| 35 | return 64; |
| 36 | }; |
| 37 | |
| 38 | char quad[4]; |
| 39 | size_t q = 0; |
| 40 | |
| 41 | for( size_t i = 0; i < str.size() && str[i] != '='; i++ ) |
| 42 | { |
| 43 | quad[q] = Index( str[i] ); |
| 44 | if( quad[q] == 64 ) |
| 45 | { |
| 46 | return {}; |
| 47 | } |
| 48 | q++; |
| 49 | if( q == 4 ) |
| 50 | { |
| 51 | q = 0; |
| 52 | result.push_back( ( ( quad[0] << 2 ) | ( quad[1] >> 4 ) ) & 0xFF ); |
| 53 | result.push_back( ( ( quad[1] & 0x0F ) << 4 ) | ( quad[2] >> 2 ) ); |
| 54 | result.push_back( ( ( quad[2] & 0x03 ) << 6 ) | quad[3] ); |
| 55 | } |
| 56 | } |
| 57 | if( q > 0 ) |
| 58 | { |
| 59 | for( size_t i = q; i < 4; i++ ) |
| 60 | { |
| 61 | quad[i] = 0; |
| 62 | } |
| 63 | result.push_back( ( ( quad[0] << 2 ) | ( quad[1] >> 4 ) ) & 0xFF ); |
| 64 | if( q > 2 ) |
| 65 | { |
| 66 | result.push_back( ( ( quad[1] & 0x0F ) << 4 ) | ( quad[2] >> 2 ) ); |
no test coverage detected