btr

alias T = int;
enum nBits = 8*T.sizeof;
T a = 0;

a.bts(0); assert(a == 1);
a.bts(1); assert(a == 3);
a.bts(2); assert(a == 7);

a.btr(0); assert(a == 6);
a.btr(1); assert(a == 4);
a.btr(2); assert(a == 0);

a.bts(0, 1, 2); assert(a == 7);
a.btr(0, 1, 2); assert(a == 0);

a.bts(8*T.sizeof - 1); assert(a != 0);
a.btr(8*T.sizeof - 1); assert(a == 0);

T b = 0;
b.bts(nBits - 1);
assert(b == T.min);

static void test(T)()
{
    enum nBits = 8*T.sizeof;
    T x = 0;
    x.bts(0);
}

test!float;
test!double;

assert(makeBit!int(2) == 4);
assert(makeBit!int(2, 3) == 12);
assert(makeBit!uint(0, 31) == 2^^31 + 1);

import std.meta : AliasSeq;
foreach (T; AliasSeq!(ubyte, ushort, uint, ulong))
{
    foreach (const n; 0 .. 8*T.sizeof)
    {
        const x = makeBit!T(n);
        assert(x == 2UL^^n);

        T y = x;
        y.resetBit(n);
        assert(y == 0);

        y.setBit(n);
        assert(y == x);
    }
}