Start experimenting with full generation of all of the numeric types.

Previously, we used a little bit of generation to drive a lot of Rust
macros. This works, but it's a little confusing to read and write. In
addition, we used a lot of implementations with variable timings based
on their input, which isn't great for crypto. This is the start of an
attempt to just generate all of the relevant Rust code directly, and to
use timing-channel resistant implementations for most of the routines.

old/signed/shift.rs

@@ -0,0 +1,135 @@
+
+macro_rules! shift_impls
+{
+    ($sname: ident, $name: ident) => {
+        impl ShlAssign<usize> for $sname {
+            fn shl_assign(&mut self, amt: usize) {
+                self.value <<= amt;
+                if self.value.is_zero() {
+                    self.negative = false;
+                }
+            }
+        }
+
+        impl Shl<usize> for $sname {
+            type Output = $sname;
+
+            fn shl(mut self, amt: usize) -> $sname {
+                self <<= amt;
+                self
+            }
+        }
+
+        impl<'a> Shl<usize> for &'a $sname {
+            type Output = $sname;
+
+            fn shl(self, amt: usize) -> $sname {
+                let mut res = self.clone();
+                res <<= amt;
+                res
+            }
+        }
+
+        impl ShrAssign<usize> for $sname {
+            fn shr_assign(&mut self, amt: usize) {
+                // arithmatic right shift is normal right shift, but always rounding
+                // to negative infinity. To implement this, we first shift right by
+                // rhs bits, and then shift that value back left rhs bits. If the two
+                // are the same, we just cleared out even bits, and there's no rounding
+                // to worry about. If they aren't the same, then we add one back.
+                let original = self.value.clone();
+                self.value >>= amt;
+                if self.negative {
+                    let review = self.value.clone() << amt;
+                    if review != original {
+                        self.value += $name::from(1u64);
+                    }
+                }
+                if self.value.is_zero() {
+                    self.negative = false;
+                }
+            }
+        }
+
+        impl Shr<usize> for $sname {
+            type Output = $sname;
+
+            fn shr(mut self, amt: usize) -> $sname {
+                self >>= amt;
+                self
+            }
+        }
+
+        impl<'a> Shr<usize> for &'a $sname {
+            type Output = $sname;
+
+            fn shr(self, amt: usize) -> $sname {
+                let mut res = self.clone();
+                res >>= amt;
+                res
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+macro_rules! generate_sigshiftl_tests {
+    ($sname: ident, $name: ident, $lname: ident) => {
+        #[test]
+        fn $lname() {
+            generate_sigshiftl_tests!(body $sname, $name, $lname);
+        }
+    };
+    (ignore $sname: ident, $name: ident, $lname: ident) => {
+        #[test]
+        #[ignore]
+        fn $lname() {
+            generate_sigshiftl_tests!(body $sname, $name, $lname);
+        }
+    };
+    (body $sname: ident, $name: ident, $lname: ident) => {
+        let fname = build_test_path("sigshiftl", stringify!($sname));
+        run_test(fname.to_string(), 3, |case| {
+            let (nega, abytes) = case.get("a").unwrap();
+            let (neg1, lbytes) = case.get("l").unwrap();
+            let (negr, rbytes) = case.get("r").unwrap();
+            assert!(!neg1);
+
+            let a = $sname::new(*nega, $name::from_bytes(abytes));
+            let l = $name::from_bytes(lbytes);
+            let r = $sname::new(*negr, $name::from_bytes(rbytes));
+            assert_eq!(r, a << usize::from(l));
+        });
+    };
+}
+
+#[cfg(test)]
+macro_rules! generate_sigshiftr_tests {
+    ($sname: ident, $name: ident, $lname: ident) => {
+        #[test]
+        fn $lname() {
+            generate_sigshiftr_tests!(body $sname, $name, $lname);
+        }
+    };
+    (ignore $sname: ident, $name: ident, $lname: ident) => {
+        #[test]
+        #[ignore]
+        fn $lname() {
+            generate_sigshiftr_tests!(body $sname, $name, $lname);
+        }
+    };
+    (body $sname: ident, $name: ident, $lname: ident) => {
+        let fname = build_test_path("sigshiftr", stringify!($sname));
+        run_test(fname.to_string(), 3, |case| {
+            let (nega, abytes) = case.get("a").unwrap();
+            let (neg1, lbytes) = case.get("l").unwrap();
+            let (negr, rbytes) = case.get("r").unwrap();
+            assert!(!neg1);
+
+            let a = $sname::new(*nega, $name::from_bytes(abytes));
+            let l = $name::from_bytes(lbytes);
+            let r = $sname::new(*negr, $name::from_bytes(rbytes));
+            assert_eq!(r, a >> usize::from(l));
+        });
+    };
+}