__int128 (Using the GNU Compiler Collection (GCC))

#### 6.1.1 128-bit Integers ¶

As an extension the integer scalar type `__int128` is supported for targets which have an integer mode wide enough to hold 128 bits. Simply write `__int128` for a signed 128-bit integer, or `unsigned __int128` for an unsigned 128-bit integer. There is no support in GCC for expressing an integer constant of type `__int128` for targets with `long long` integer less than 128 bits wide.