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134 lines
3.1 KiB
Plaintext
134 lines
3.1 KiB
Plaintext
module base64;
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// Based on the C2 version.
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fault DecodingError
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{
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INVALID_CHARACTER
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}
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const char[64] LUT_ENC = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
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'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
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'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
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'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
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'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
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'w', 'x', 'y', 'z', '0', '1', '2', '3',
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'4', '5', '6', '7', '8', '9', '+', '/',
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};
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const char ERR = 0xFF;
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const char[256] LUT_DEC =
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{
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[0..255] = ERR,
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['A'] = 0, ['B'] = 1, ['C'] = 2, ['D'] = 3, ['E'] = 4,
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['F'] = 5, ['G'] = 6, ['H'] = 7, ['I'] = 8, ['J'] = 9,
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['K'] = 10, ['L'] = 11, ['M'] = 12, ['N'] = 13, ['O'] = 14,
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['P'] = 15, ['Q'] = 16, ['R'] = 17, ['S'] = 18, ['T'] = 19,
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['U'] = 20, ['V'] = 21, ['W'] = 22, ['X'] = 23, ['Y'] = 24,
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['Z'] = 25, ['a'] = 26, ['b'] = 27, ['c'] = 28, ['d'] = 29,
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['e'] = 30, ['f'] = 31, ['g'] = 32, ['h'] = 33, ['i'] = 34,
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['j'] = 35, ['k'] = 36, ['l'] = 37, ['m'] = 38, ['n'] = 39,
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['o'] = 40, ['p'] = 41, ['q'] = 42, ['r'] = 43, ['s'] = 44,
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['t'] = 45, ['u'] = 46, ['v'] = 47, ['w'] = 48, ['x'] = 49,
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['y'] = 50, ['z'] = 51, ['0'] = 52, ['1'] = 53, ['2'] = 54,
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['3'] = 55, ['4'] = 56, ['5'] = 57, ['6'] = 58, ['7'] = 59,
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['8'] = 60, ['9'] = 61, ['+'] = 62, ['/'] = 63
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};
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const char PAD = '=';
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const char FIRST = '+';
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const char LAST = 'z';
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fn void encode(char[] in, char *out)
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{
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int j = 0;
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char c = LUT_ENC[1];
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for (int i = 0; i < in.len; i++)
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{
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switch (i % 3)
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{
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case 0:
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out[j++] = LUT_ENC[(in[i] >> 2) & 0x3F];
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case 1:
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out[j++] = LUT_ENC[(in[i - 1] & 0x3) << 4 + ((in[i] >> 4) & 0xF)];
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case 2:
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out[j++] = LUT_ENC[(in[i - 1] & 0xF) << 2 + ((in[i] >> 6) & 0x3)];
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out[j++] = LUT_ENC[in[i] & 0x3F];
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}
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}
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// move back
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usz last = in.len - 1;
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// check the last and add padding
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switch (last % 3)
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{
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case 0:
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out[j++] = LUT_ENC[(in[last] & 0x3) << 4];
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out[j++] = PAD;
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out[j++] = PAD;
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case 1:
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out[j++] = LUT_ENC[(in[last] & 0xF) << 2];
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out[j++] = PAD;
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}
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}
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fn int! decode(String in, char* out, int* invalid_char_index = null)
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{
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int j = 0;
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for (int i = 0; i < in.len; i++)
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{
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char value = in[i];
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if (value == PAD) return j;
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char c = LUT_DEC[in[i]];
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if (c == ERR)
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{
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if (invalid_char_index) *invalid_char_index = i;
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return DecodingError.INVALID_CHARACTER?;
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}
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switch (i % 4)
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{
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case 0:
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out[j] = c << 2;
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case 1:
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out[j++] += c >> 4 & 0x3;
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// if not last char with padding
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if (i < (in.len - 3) || in[(long)(in.len) - 2] != PAD)
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{
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out[j] = (c & 0xF) << 4;
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}
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case 2:
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out[j++] += c >> 2 & 0xF;
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if (i < (in.len - 2) || in[(long)(in.len) - 1] != PAD)
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{
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out[j] = (c & 0x3) << 6;
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}
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case 3:
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out[j++] += c;
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}
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}
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return j;
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}
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extern fn void printf(char *fmt, ...);
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fn void main()
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{
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char *helloworld = "Hello World\n";
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char[1000] buffer;
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encode(helloworld[0..12], &buffer);
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printf("Result: %s\n", &buffer);
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char *to_decode = "aGVsbG8gd29ybGRcMA==";
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char[?] result = b64"aGVsbG8gd29ybGRcMA==";
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decode((String)to_decode[0..19], &buffer)!!;
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printf("Result: %s\n", &buffer);
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printf("Result direct: %.*s\n", 13, &result);
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} |