/*
    Copyright (C) 2014-2019 de4dot@gmail.com

    This file is part of dnSpy

    dnSpy is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    dnSpy is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with dnSpy.  If not, see <http://www.gnu.org/licenses/>.
*/

namespace dnSpy.Debugger.DotNet.Metadata {
	static class HexUtils {
		public static byte[]? ParseBytes(string hexString) {
			try {
				if (hexString.Length % 2 != 0)
					return null;
				var bytes = new byte[hexString.Length / 2];
				for (int i = 0; i < hexString.Length; i += 2) {
					int upper = TryParseHexChar(hexString[i]);
					int lower = TryParseHexChar(hexString[i + 1]);
					if (upper < 0 || lower < 0)
						return null;
					bytes[i / 2] = (byte)((upper << 4) | lower);
				}
				return bytes;
			}
			catch {
				return null;
			}
		}

		static int TryParseHexChar(char c) {
			if ('0' <= c && c <= '9')
				return (ushort)c - (ushort)'0';
			if ('a' <= c && c <= 'f')
				return 10 + (ushort)c - (ushort)'a';
			if ('A' <= c && c <= 'F')
				return 10 + (ushort)c - (ushort)'A';
			return -1;
		}
	}
}