static uint32_t
utf8_encode(uint8_t out[4], uint32_t cp)
{
	uint32_t result;
	if (cp <= 0x7F) {
		out[0] = cp & 0x7F;
		result = 1;
	} else if (cp <= 0x7FF) {
		result = 2;
		out[0] = ((cp >>  6) & 0x1F) | 0xC0;
		out[1] = ((cp >>  0) & 0x3F) | 0x80;
	} else if (cp <= 0xFFFF) {
		result = 3;
		out[0] = ((cp >> 12) & 0x0F) | 0xE0;
		out[1] = ((cp >>  6) & 0x3F) | 0x80;
		out[2] = ((cp >>  0) & 0x3F) | 0x80;
	} else if (cp <= 0x10FFFF) {
		result = 4;
		out[0] = ((cp >> 18) & 0x07) | 0xF0;
		out[1] = ((cp >> 12) & 0x3F) | 0x80;
		out[2] = ((cp >>  6) & 0x3F) | 0x80;
		out[3] = ((cp >>  0) & 0x3F) | 0x80;
	} else {
		//out[0] = '?';
		result = 0;
	}
	return result;
}