The x86-64 instruction set can do 64-bit*64-bit to 128-bit using one instruction (mul for unsigned imul for signed each with one operand) so I would argue that to some degree that the x86 instruction set does include some support for 128-bit integers. If your instruction set does not have an instruction to do 64-bit*64-bit to … Read more
It’s here in System.Numerics. “The BigInteger type is an immutable type that represents an arbitrarily large integer whose value in theory has no upper or lower bounds.” var i = System.Numerics.BigInteger.Parse(“10000000000000000000000000000000”);
If you don’t need any of the fancy formatting options, writing your own << operator is trivial. Formally, I suspect that writing one for __int128_t would be considered undefined behavior, but practically, I think it would work, up until the library starts providing actual support for it (at which point, you’d retire your conversion operator). … Read more
MSDN doesn’t list it as being available, and this recent response agrees, so officially, no, there is no type called __int128 and it can’t be enabled. Additionally, never trust the syntax hilighter; it is user editable, and thus likely to either have bogus or ‘future’ types in it. (it is probably a reserved word however, … Read more