Add Sint128 type & libfuncs (#384)

* Push progress

* Parse Sint8 result value

* Improve sub test + fix how signed values are compared against vm values

* Clippy

* Improve testing

* Fix

* Try stuff

* Fix typos

* Fix test values

* Add test & fix wide_mul

* First draft of diff libfunc

* Improve test

* Remove old code

* Add test

* Add Sint16 type + libfuncs

* fmt

* Push progress

* Remove uneeded intermidiate variables

* Update code

* Update code

* Add tests for i64 libfuncs

* Adjust test values

* Fix cairo programs

* fmt

* Remove old file

* Fix comment

* Add sint128 type + libfuncs

* Add tests

* Add tests

src/libfuncs.rs

@@ -41,6 +41,7 @@ pub mod mem;
 pub mod nullable;
 pub mod pedersen;
 pub mod poseidon;
+pub mod sint128;
 pub mod sint16;
 pub mod sint32;
 pub mod sint64;
@@ -215,7 +216,9 @@ where
             CoreConcreteLibfunc::Sint64(info) => {
                 self::sint64::build(context, registry, entry, location, helper, metadata, info)
             }
-            CoreConcreteLibfunc::Sint128(_) => todo!(),
+            CoreConcreteLibfunc::Sint128(info) => {
+                self::sint128::build(context, registry, entry, location, helper, metadata, info)
+            }
             CoreConcreteLibfunc::Bytes31(_) => todo!(),
         }
     }