#include <stdio.h>
#include <stdint.h>
#include <assert.h>
// buffer length must be 4 bytes.
uint8_t code_point_to_utf8(uint8_t *buffer, uint32_t code_point)
{
if (code_point < (1 << 7)){
buffer[0] = (uint8_t)code_point;
return 1;
}
else if(code_point < (1 << 11)){
buffer[0] = 0b11000000 | (code_point & 0b11111000000) >> 6;
buffer[1] = 0b10000000 | (code_point & 0b00000111111) >> 0;
return 2;
}
else if(code_point < (1 << 16)){
buffer[0] = 0b11100000 | (code_point & 0b1111000000000000) >> 12;
buffer[1] = 0b10000000 | (code_point & 0b0000111111000000) >> 6;
buffer[2] = 0b10000000 | (code_point & 0b0000000000111111) >> 0;
return 3;
}
else if(code_point < (1 << 21)){
buffer[0] = 0b11110000 | (code_point & 0b111000000000000000000) >> 18;
buffer[1] = 0b10000000 | (code_point & 0b000111111000000000000) >> 12;
buffer[2] = 0b10000000 | (code_point & 0b000000000111111000000) >> 6;
buffer[3] = 0b10000000 | (code_point & 0b000000000000000111111) >> 0;
return 4;
}
else
{
return 0;
}
}
void print_utf8(uint32_t code_point)
{
uint8_t buffer[4] = {};
uint8_t len = code_point_to_utf8(buffer, code_point);
printf("%.*s", len, buffer);
}
int32_t main(void)
{
print_utf8(0xC5);
print_utf8(0x41);
print_utf8(0x030A);
putchar('\n');
print_utf8('1');
print_utf8('5');
print_utf8(0x2044);
print_utf8('2');
print_utf8('3');
putchar('\n');
print_utf8(0x092B);
print_utf8(0x093F);
putchar('\n');
print_utf8(0x2615);
print_utf8(0x20DF);
putchar('\n');
return 0;
}
