Reading and writing CUInt

cuint.d

import std.bitmanip;
import std.range.primitives;

alias read = std.bitmanip.read;
uint read(T : CUInt, R)(auto ref R range)
if (isInputRange!R && is(ElementType!R : const(ubyte))) {
    return CUInt(range).value;
}

alias append = std.bitmanip.append;
void append(T : CUInt, R)(R range, uint value)
if (isOutputRange!(R, ubyte)) {
    CUInt(range, value);
}

struct CUInt {
    uint value;
	
    this(R)(auto ref R rng) if (isInputRange!R && is(ElementType!R : const(ubyte))) {
        auto code = rng.peek!ubyte;
        switch (code & 0xE0) {
            case 0xE0:
				rng.read!ubyte;
                value = rng.read!uint;
                break;
            case 0xC0:
                value = rng.read!uint & 0x1FFFFFFF;
                break;
			case 0x80:
			case 0xA0:
				value = rng.read!ushort & 0x3FFF;
				break;
			default:
				value = rng.read!ubyte;
				break;
        }
    }
	
	this(R)(R rng, int val) if (isOutputRange!(R, ubyte)) {
		if (val <= 0x7F)
			rng.append!ubyte(*cast(ubyte*) &val);
		else if (val < 0x3FFF) {
			auto val_ = *cast(ushort*) &val;
			val_ |= 0x8000;
			rng.append!ushort(val_);
		}
		else if (val <= 0x1FFFFFFF)
			rng.append!uint(val | 0xC0000000);
		else {
			rng.append!ubyte(0xE0);
			rng.append!uint(val);
		}
	}
}