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#include "utf8.h"
size_t codepoint_to_utf8(const uint32_t codepoint, unsigned char buffer[4]) {
if (codepoint <= 0x7F) {
buffer[0] = codepoint;
return 1;
}
if (codepoint >= 0x80 && codepoint <= 0x07FF) {
buffer[0] = 0xC0 | (codepoint >> 6);
buffer[1] = 0x80 | (codepoint & 0x3F);
return 2;
}
if (codepoint >= 0x0800 && codepoint <= 0xFFFF) {
buffer[0] = 0xE0 | (codepoint >> 12);
buffer[1] = 0x80 | ((codepoint >> 6) & 0x3F);
buffer[2] = 0x80 | (codepoint & 0x3F);
return 3;
}
if (codepoint >= 0x10000 && codepoint <= 0x10FFFF) {
buffer[0] = 0xF0 | (codepoint >> 18);
buffer[1] = 0x80 | ((codepoint >> 12) & 0x3F);
buffer[2] = 0x80 | ((codepoint >> 6) & 0x3F);
buffer[3] = 0x80 | (codepoint & 0x3F);
return 4;
}
return 0;
}
bool utf8_to_codepoint(const unsigned char buffer[4], const size_t len,
uint32_t *codepoint) {
*codepoint = 0;
if (len == 1 && buffer[0] <= 0x7F) {
*codepoint = buffer[0];
return true;
}
if (len == 2 && (buffer[0] >= 0xC0 && buffer[0] <= 0xDF) &&
(buffer[1] >= 0x80 && buffer[1] <= 0xBF)) {
*codepoint = buffer[0] & 0x1F;
*codepoint = *codepoint << 6;
*codepoint = *codepoint | (buffer[1] & 0x3F);
return true;
}
if (len == 3 && (buffer[0] >= 0xE0 && buffer[0] <= 0xEF) &&
(buffer[1] >= 0x80 && buffer[1] <= 0xBF) &&
(buffer[2] >= 0x80 && buffer[2] <= 0xBF)) {
*codepoint = buffer[0] & 0xF;
*codepoint = *codepoint << 6;
*codepoint = *codepoint | (buffer[1] & 0x3F);
*codepoint = *codepoint << 6;
*codepoint = *codepoint | (buffer[2] & 0x3F);
return true;
}
if (len == 4 && (buffer[0] >= 0xF0 && buffer[0] <= 0xF7) &&
(buffer[1] >= 0x80 && buffer[1] <= 0xBF) &&
(buffer[2] >= 0x80 && buffer[2] <= 0xBF) &&
(buffer[3] >= 0x80 && buffer[3] <= 0xBF)) {
*codepoint = buffer[0] & 7;
*codepoint = *codepoint << 6;
*codepoint = *codepoint | (buffer[1] & 0x3F);
*codepoint = *codepoint << 6;
*codepoint = *codepoint | (buffer[2] & 0x3F);
*codepoint = *codepoint << 6;
*codepoint = *codepoint | (buffer[3] & 0x3F);
return true;
}
return false;
}
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