BAN: Add function to decode utf-8 encoded strings

works for 3 byte unicode characters

BAN/include/BAN/UTF8.h

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+namespace BAN
+{
+
+	static constexpr uint16_t utf8_to_codepoint(uint8_t* bytes, size_t count)
+	{
+		if (count > 3)
+			return 0xFFFF;
+
+		for (size_t i = 1; i < count; i++)
+			if ((bytes[i] & 0xC0) != 0x80)
+				return 0xFFFF;
+
+		switch (count)
+		{
+			case 1: return   bytes[0];
+			case 2: return ((bytes[0] & 0x1F) <<  6) |  (bytes[1] & 0x3F);
+			case 3: return ((bytes[0] & 0x1F) << 12) | ((bytes[1] & 0x3F) << 6) | (bytes[2] & 0x3F);
+		}
+
+		return 0xFFFF;
+	}
+
+}