85 lines
3.0 KiB
C
85 lines
3.0 KiB
C
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#include "unicode.h"
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size_t utf8_Decode(const char *utf8, size_t len, uint32_t *codepoint) {
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// Some useful precomputed data
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static const int trailing[256] =
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{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5};
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static const uint32_t offsets[6] =
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{0x00000000, 0x00003080, 0x000E2080, 0x03C82080, 0xFA082080, 0x82082080};
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// decode the character
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uint32_t output;
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int trailingBytes;
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// read the first byte
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uint8_t first = *utf8;
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trailingBytes = trailing[first];
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if ((first >= HELOS_UTF8_CONTINUATION_MIN && first <= HELOS_UTF8_OVERLONG_LEADER_2) ||
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(first >= HELOS_UTF8_INVALID_LEADER_MIN && first <= HELOS_UTF8_INVALID_LEADER_MAX) ||
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trailingBytes + 1 > len) {
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// corrupted data or incomplete character
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trailingBytes = 0;
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if (codepoint != 0)
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(*codepoint) = HELOS_UNICODE_ERROR;
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} else if (codepoint != 0) {
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output = 0;
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// so elegant!
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switch (trailingBytes) {
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case 5: output += (uint8_t)(*utf8++); output <<= 6;
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case 4: output += (uint8_t)(*utf8++); output <<= 6;
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case 3: output += (uint8_t)(*utf8++); output <<= 6;
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case 2: output += (uint8_t)(*utf8++); output <<= 6;
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case 1: output += (uint8_t)(*utf8++); output <<= 6;
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case 0: output += (uint8_t)(*utf8++);
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}
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(*codepoint) = output - offsets[trailingBytes];
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}
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return trailingBytes + 1;
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}
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size_t utf8_EncodeLength(uint32_t codepoint) {
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if (codepoint <= 0x007f) // 0000 ~ 007F
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return 1;
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else if (codepoint <= 0x07ff) // 0080 ~ 07FF
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return 2;
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else if (codepoint <= 0xffff) // 0800 ~ FFFF
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return 3;
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else if (codepoint <= 0x10ffff) // 10000 ~ 10FFFF
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return 4;
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return 0; // invalid
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}
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size_t utf8_Encode(char *utf8, uint32_t codepoint) {
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// Some useful precomputed data
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static const uint8_t firstBytes[7] = {0x00, 0x00, 0xC0, 0xE0, 0xF0, 0xF8, 0xFC};
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if (codepoint > HELOS_UNICODE_MAX)
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codepoint = HELOS_UNICODE_ERROR; // substitute invalid codepoint
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// get the number of bytes to write
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size_t len = utf8_EncodeLength(codepoint);
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// write the bytes
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// so elegant also!
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switch (len) {
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case 4: utf8[3] = (char)((codepoint | 0x80) & 0xBF); codepoint >>= 6;
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case 3: utf8[2] = (char)((codepoint | 0x80) & 0xBF); codepoint >>= 6;
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case 2: utf8[1] = (char)((codepoint | 0x80) & 0xBF); codepoint >>= 6;
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case 1: utf8[0] = (char)(codepoint | firstBytes[len]);
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}
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return len;
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}
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