Function unicode_to_utf8

src/common/wchar.c:501–528

* Map a Unicode code point to UTF-8. utf8string must have 4 bytes of * space allocated. */

 * space allocated.
 */
unsigned char *
unicode_to_utf8(pg_wchar c, unsigned char *utf8string)
{
	if (c <= 0x7F)
	{
		utf8string[0] = c;
	}
	else if (c <= 0x7FF)
	{
		utf8string[0] = 0xC0 | ((c >> 6) & 0x1F);
		utf8string[1] = 0x80 | (c & 0x3F);
	}
	else if (c <= 0xFFFF)
	{
		utf8string[0] = 0xE0 | ((c >> 12) & 0x0F);
		utf8string[1] = 0x80 | ((c >> 6) & 0x3F);
		utf8string[2] = 0x80 | (c & 0x3F);
	}
	else
	{
		utf8string[0] = 0xF0 | ((c >> 18) & 0x07);
		utf8string[1] = 0x80 | ((c >> 12) & 0x3F);
		utf8string[2] = 0x80 | ((c >> 6) & 0x3F);
		utf8string[3] = 0x80 | (c & 0x3F);
	}

	return utf8string;
}

/*
 * Trivial conversion from pg_wchar to UTF-8.