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/scale.rs

@@ -0,0 +1,121 @@
+macro_rules! scale_impls
+{
+    ($base: ident, $big: ident) => {
+        scale_impls!($base, $big, u8);
+        scale_impls!($base, $big, u16);
+        scale_impls!($base, $big, u32);
+        scale_impls!($base, $big, u64);
+        scale_impls!($base, $big, usize);
+
+        scale_impls!($base, $big, scaled i8);
+        scale_impls!($base, $big, scaled i16);
+        scale_impls!($base, $big, scaled i32);
+        scale_impls!($base, $big, scaled i64);
+        scale_impls!($base, $big, scaled isize);
+    };
+    ($base: ident, $big: ident, $prim: ident) => {
+        impl Mul<$prim> for $base {
+            type Output = $big;
+
+            fn mul(self, factor: $prim) -> $big {
+                &self * factor
+            }
+        }
+
+        impl<'a> Mul<$prim> for &'a $base {
+            type Output = $big;
+
+            fn mul(self, factor: $prim) -> $big {
+                let mut res = $big::zero();
+                scale(&mut res.value.value, &self.value.value, factor as u64);
+                res.negative = self.negative && !res.value.is_zero();
+                res
+            }
+        }
+
+        impl Mul<$base> for $prim {
+            type Output = $big;
+
+            fn mul(self, rhs: $base) -> $big {
+                rhs.mul(self)
+            }
+        }
+
+        impl<'a> Mul<&'a $base> for $prim {
+            type Output = $big;
+
+            fn mul(self, rhs: &$base) -> $big {
+                rhs.mul(self)
+            }
+        }
+    };
+    ($base: ident, $big: ident, scaled $prim: ident) => {
+        impl Mul<$prim> for $base {
+            type Output = $big;
+
+            fn mul(self, factor: $prim) -> $big {
+                &self * factor
+            }
+        }
+
+        impl<'a> Mul<$prim> for &'a $base {
+            type Output = $big;
+
+            fn mul(self, factor: $prim) -> $big {
+                let mut res = $big::zero();
+                scale(&mut res.value.value, &self.value.value, factor.abs() as u64);
+                res.negative = (self.negative ^ (factor < 0)) && !res.value.is_zero();
+                res
+            }
+        }
+
+        impl Mul<$base> for $prim {
+            type Output = $big;
+
+            fn mul(self, rhs: $base) -> $big {
+                rhs.mul(self)
+            }
+        }
+
+        impl<'a> Mul<&'a $base> for $prim {
+            type Output = $big;
+
+            fn mul(self, rhs: &$base) -> $big {
+                rhs.mul(self)
+            }
+        }
+    };
+}
+
+#[cfg(test)]
+macro_rules! generate_sigscale_tests
+{
+    ($name: ident, $uname: ident, $lname: ident, $big: ident, $ubig: ident) => {
+        #[test]
+        fn $lname() {
+            generate_sigscale_tests!(body $name, $uname, $lname, $big, $ubig);
+        }
+    };
+    (ignore $name: ident, $uname:ident, $lname: ident, $big: ident, $ubig: ident) => {
+        #[test]
+        #[ignore]
+        fn $lname() {
+            generate_sigscale_tests!(body $name, $uname, $lname, $big, $ubig);
+        }
+    };
+    (body $name: ident, $uname: ident, $lname: ident, $big: ident, $ubig: ident) => {
+        let fname = build_test_path("sigscale", stringify!($name));
+        run_test(fname.to_string(), 3, |case| {
+            let (nega, abytes) = case.get("a").unwrap();
+            let (negb, bbytes) = case.get("b").unwrap();
+            let (negc, cbytes) = case.get("c").unwrap();
+
+            let a    = $name::new(*nega, $uname::from_bytes(abytes));
+            let bbig = $name::new(*negb, $uname::from_bytes(bbytes));
+            let c    = $big::new(*negc, $ubig::from_bytes(cbytes));
+            let b    = i64::from(&bbig);
+            let res = &a * b;
+            assert_eq!(c, res);
+        });
+    };
+}