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/unsigned/add.rs

@@ -0,0 +1,136 @@
+pub fn addition(dest: &mut [u64], src: &[u64])
+{
+    assert_eq!(dest.len(), src.len() + 1);
+    let mut carry: u128 = 0;
+
+    for i in 0..src.len() {
+        let x128 = dest[i] as u128;
+        let y128 = src[i] as u128;
+        let z128 = x128 + y128 + carry;
+
+        dest[i] = z128 as u64;
+        carry = z128 >> 64;
+    }
+    dest[src.len()] = carry as u64;
+}
+
+pub fn unsafe_addition(dest: &mut [u64], src: &[u64], really_unsafe: bool)
+{
+    assert_eq!(dest.len(), src.len());
+    let mut carry: u128 = 0;
+
+    for i in 0..src.len() {
+        let x128 = dest[i] as u128;
+        let y128 = src[i] as u128;
+        let z128 = x128 + y128 + carry;
+
+        dest[i] = z128 as u64;
+        carry = z128 >> 64;
+    }
+
+    if !really_unsafe {
+        assert_eq!(carry, 0, "Unsafe overflow in AddAssign");
+    }
+}
+
+macro_rules! addition_impls
+{
+    ($base: ident, $bigger: ident) => {
+        impl AddAssign<$base> for $base {
+            fn add_assign(&mut self, rhs: $base) {
+                unsafe_addition(&mut self.value, &rhs.value, false);
+            }
+        }
+
+        impl<'a> AddAssign<&'a $base> for $base {
+            fn add_assign(&mut self, rhs: &$base) {
+                unsafe_addition(&mut self.value, &rhs.value, false);
+            }
+        }
+
+        impl Add<$base> for $base {
+            type Output = $bigger;
+
+            fn add(self, rhs: $base) -> $bigger
+            {
+                let mut dest = $bigger::zero();
+                &dest.value[0..rhs.value.len()].copy_from_slice(&self.value);
+                addition(&mut dest.value, &rhs.value);
+                dest
+            }
+        }
+
+        impl<'a> Add<&'a $base> for $base {
+            type Output = $bigger;
+
+            fn add(self, rhs: &$base) -> $bigger
+            {
+                let mut dest = $bigger::zero();
+                &dest.value[0..rhs.value.len()].copy_from_slice(&self.value);
+                addition(&mut dest.value, &rhs.value);
+                dest
+            }
+        }
+
+        impl<'a> Add<$base> for &'a $base {
+            type Output = $bigger;
+
+            fn add(self, rhs: $base) -> $bigger
+            {
+                let mut dest = $bigger::zero();
+                &dest.value[0..rhs.value.len()].copy_from_slice(&self.value);
+                addition(&mut dest.value, &rhs.value);
+                dest
+            }
+        }
+
+        impl<'a,'b> Add<&'a $base> for &'b $base {
+            type Output = $bigger;
+
+            fn add(self, rhs: &$base) -> $bigger
+            {
+                let mut dest = $bigger::zero();
+                &dest.value[0..rhs.value.len()].copy_from_slice(&self.value);
+                addition(&mut dest.value, &rhs.value);
+                dest
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+macro_rules! generate_add_tests {
+    ($name: ident, $lname: ident, $plus1: ident) => {
+        #[test]
+        fn $lname() {
+            generate_add_tests!(body $name, $lname, $plus1);
+        }
+    };
+    (ignore $name: ident, $lname: ident, $plus1: ident) => {
+        #[test]
+        #[ignore]
+        fn $lname() {
+            generate_add_tests!(body $name, $lname, $plus1);
+        }
+    };
+    (body $name: ident, $lname: ident, $plus1: ident) => {
+        let fname = build_test_path("add", stringify!($name));
+        run_test(fname.to_string(), 3, |case| {
+            let (neg0, abytes) = case.get("a").unwrap();
+            let (neg1, bbytes) = case.get("b").unwrap();
+            let (neg2, cbytes) = case.get("c").unwrap();
+            assert!(!neg0 && !neg1 && !neg2);
+
+            let a = $name::from_bytes(abytes);
+            let b = $name::from_bytes(bbytes);
+            let c = $plus1::from_bytes(cbytes);
+            assert_eq!(c, &a + &b);
+
+            if c.value[c.value.len()-1] == 0 {
+                let mut aprime = a.clone();
+                aprime += b;
+                assert_eq!($name::from(c), aprime);
+            }
+        });
+    };
+}