Function asStringEncodeUTF8

sdk/angelscript/source/as_string_util.cpp:238–275

The function will encode the unicode code point into the outEncodedBuffer, and then return the length of the encoded value. If the input value is not a valid unicode code point, then the function will return -1. This function is taken from the AngelCode ToolBox.

// This function is taken from the AngelCode ToolBox.
//
int asStringEncodeUTF8(unsigned int value, char *outEncodedBuffer)
{
	unsigned char *buf = (unsigned char*)outEncodedBuffer;

	int length = -1;

	if( value <= 0x7F )
	{
		buf[0] = static_cast<unsigned char>(value);
		return 1;
	}
	else if( value >= 0x80 && value <= 0x7FF )
	{
		// Encode it with 2 characters
		buf[0] = static_cast<unsigned char>(0xC0 + (value >> 6));
		length = 2;
	}
	else if( (value >= 0x800 && value <= 0xD7FF) || (value >= 0xE000 && value <= 0xFFFF) )
	{
		// Note: Values 0xD800 to 0xDFFF are not valid unicode characters
		buf[0] = static_cast<unsigned char>(0xE0 + (value >> 12));
		length = 3;
	}
	else if( value >= 0x10000 && value <= 0x10FFFF )
	{
		buf[0] = static_cast<unsigned char>(0xF0 + (value >> 18));
		length = 4;
	}

	int n = length-1;
	for( ; n > 0; n-- )
	{
		buf[n] = static_cast<unsigned char>(0x80 + (value & 0x3F));
		value >>= 6;
	}

	return length;
}

//
// The function will decode an UTF8 character and return the unicode code point.