Base implementation of signed numbers and EGCD, with tests.

src/signed/modinv.rs

@@ -0,0 +1,14 @@
+macro_rules! modinv_impls {
+    ($sname: ident) => {
+    };
+}
+
+#[cfg(test)]
+macro_rules! generate_modinv_tests {
+    ($sname: ident, $tname: ident, $mname: ident) => {
+    };
+    (ignore $sname: ident, $tname: ident, $mname: ident) => {
+    };
+    (body $sname: ident, $tname: ident, $mname: ident) => {
+    };
+}