43 lines
1.4 KiB
C++
43 lines
1.4 KiB
C++
#include "utf8.hpp"
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size_t utf8_codepoint_size(char32_t codepoint) {
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if (0 == ((char32_t)0xffffff80 & codepoint)) {
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return 1;
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} else if (0 == ((char32_t)0xfffff800 & codepoint)) {
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return 2;
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} else if (0 == ((char32_t)0xffff0000 & codepoint)) {
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return 3;
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} else {
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return 4;
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}
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}
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char *utf8_write_codepoint(char *str, char32_t codepoint) {
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if (0 == ((char32_t)0xffffff80 & codepoint)) {
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/* 1-byte/7-bit ascii
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* (0b0xxxxxxx) */
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str[0] = (char)codepoint;
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str += 1;
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} else if (0 == ((char32_t)0xfffff800 & codepoint)) {
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/* 2-byte/11-bit utf8 code point
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* (0b110xxxxx 0b10xxxxxx) */
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str[0] = (char)(0xc0 | (char)((codepoint >> 6) & 0x1f));
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str[1] = (char)(0x80 | (char)(codepoint & 0x3f));
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str += 2;
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} else if (0 == ((char32_t)0xffff0000 & codepoint)) {
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/* 3-byte/16-bit utf8 code point
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* (0b1110xxxx 0b10xxxxxx 0b10xxxxxx) */
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str[0] = (char)(0xe0 | (char)((codepoint >> 12) & 0x0f));
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str[1] = (char)(0x80 | (char)((codepoint >> 6) & 0x3f));
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str[2] = (char)(0x80 | (char)(codepoint & 0x3f));
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str += 3;
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} else { /* if (0 == ((int)0xffe00000 & chr)) { */
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str[0] = (char)(0xf0 | (char)((codepoint >> 18) & 0x07));
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str[1] = (char)(0x80 | (char)((codepoint >> 12) & 0x3f));
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str[2] = (char)(0x80 | (char)((codepoint >> 6) & 0x3f));
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str[3] = (char)(0x80 | (char)(codepoint & 0x3f));
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str += 4;
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}
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return str;
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}
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