Support 16-bit pointers as well as i/usize

This is based on the original work of Dylan McKay for the
[avr-rust project][ar].

[ar]: https://github.com/avr-rust/rust

6 files changed, 46 insertions, 0 deletions

diff --git a/src/libcore/fmt/num.rs b/src/libcore/fmt/num.rs
index a944c996c1a..d55e0317a94 100644
--- a/src/libcore/fmt/num.rs
+++ b/src/libcore/fmt/num.rs
@@ -29,6 +29,7 @@ trait Int: Zero + PartialEq + PartialOrd + Div<Output=Self> + Rem<Output=Self> +
            Sub<Output=Self> + Copy {
     fn from_u8(u: u8) -> Self;
     fn to_u8(&self) -> u8;
+    fn to_u16(&self) -> u16;
     fn to_u32(&self) -> u32;
     fn to_u64(&self) -> u64;
 }
@@ -37,6 +38,7 @@ macro_rules! doit {
     ($($t:ident)*) => ($(impl Int for $t {
         fn from_u8(u: u8) -> $t { u as $t }
         fn to_u8(&self) -> u8 { *self as u8 }
+        fn to_u16(&self) -> u16 { *self as u16 }
         fn to_u32(&self) -> u32 { *self as u32 }
         fn to_u64(&self) -> u64 { *self as u64 }
     })*)
@@ -256,6 +258,8 @@ macro_rules! impl_Display {
 
 impl_Display!(i8, u8, i16, u16, i32, u32: to_u32);
 impl_Display!(i64, u64: to_u64);
+#[cfg(target_pointer_width = "16")]
+impl_Display!(isize, usize: to_u16);
 #[cfg(target_pointer_width = "32")]
 impl_Display!(isize, usize: to_u32);
 #[cfg(target_pointer_width = "64")]
diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index a0f2a2adcb6..5c2179ccf33 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -518,6 +518,10 @@ pub fn replace<T>(dest: &mut T, mut src: T) -> T {
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn drop<T>(_x: T) { }
 
+macro_rules! repeat_u8_as_u16 {
+    ($name:expr) => { (($name as u16) <<  8 |
+                       ($name as u16)) }
+}
 macro_rules! repeat_u8_as_u32 {
     ($name:expr) => { (($name as u32) << 24 |
                        ($name as u32) << 16 |
@@ -543,11 +547,18 @@ macro_rules! repeat_u8_as_u64 {
 pub const POST_DROP_U8: u8 = 0x1d;
 #[unstable(feature = "filling_drop", issue = "5016")]
 #[allow(missing_docs)]
+pub const POST_DROP_U16: u16 = repeat_u8_as_u16!(POST_DROP_U8);
+#[unstable(feature = "filling_drop", issue = "5016")]
+#[allow(missing_docs)]
 pub const POST_DROP_U32: u32 = repeat_u8_as_u32!(POST_DROP_U8);
 #[unstable(feature = "filling_drop", issue = "5016")]
 #[allow(missing_docs)]
 pub const POST_DROP_U64: u64 = repeat_u8_as_u64!(POST_DROP_U8);
 
+#[cfg(target_pointer_width = "16")]
+#[unstable(feature = "filling_drop", issue = "5016")]
+#[allow(missing_docs)]
+pub const POST_DROP_USIZE: usize = POST_DROP_U16 as usize;
 #[cfg(target_pointer_width = "32")]
 #[unstable(feature = "filling_drop", issue = "5016")]
 #[allow(missing_docs)]
diff --git a/src/libcore/num/isize.rs b/src/libcore/num/isize.rs
index de5b1777f93..86bcef4011d 100644
--- a/src/libcore/num/isize.rs
+++ b/src/libcore/num/isize.rs
@@ -14,6 +14,8 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+#[cfg(target_pointer_width = "16")]
+int_module! { isize, 16 }
 #[cfg(target_pointer_width = "32")]
 int_module! { isize, 32 }
 #[cfg(target_pointer_width = "64")]
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index 9b6f6698def..5988a6375d4 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -1176,6 +1176,15 @@ impl i64 {
         intrinsics::mul_with_overflow }
 }
 
+#[cfg(target_pointer_width = "16")]
+#[lang = "isize"]
+impl isize {
+    int_impl! { i16, u16, 16,
+        intrinsics::add_with_overflow,
+        intrinsics::sub_with_overflow,
+        intrinsics::mul_with_overflow }
+}
+
 #[cfg(target_pointer_width = "32")]
 #[lang = "isize"]
 impl isize {
@@ -2188,6 +2197,18 @@ impl u64 {
         intrinsics::mul_with_overflow }
 }
 
+#[cfg(target_pointer_width = "16")]
+#[lang = "usize"]
+impl usize {
+    uint_impl! { u16, 16,
+        intrinsics::ctpop,
+        intrinsics::ctlz,
+        intrinsics::cttz,
+        intrinsics::bswap,
+        intrinsics::add_with_overflow,
+        intrinsics::sub_with_overflow,
+        intrinsics::mul_with_overflow }
+}
 #[cfg(target_pointer_width = "32")]
 #[lang = "usize"]
 impl usize {
diff --git a/src/libcore/num/usize.rs b/src/libcore/num/usize.rs
index 0c7d16a41bc..685c52e271e 100644
--- a/src/libcore/num/usize.rs
+++ b/src/libcore/num/usize.rs
@@ -14,6 +14,8 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
+#[cfg(target_pointer_width = "16")]
+uint_module! { usize, 16 }
 #[cfg(target_pointer_width = "32")]
 uint_module! { usize, 32 }
 #[cfg(target_pointer_width = "64")]
diff --git a/src/libcore/num/wrapping.rs b/src/libcore/num/wrapping.rs
index 04e8bc4913b..4857817e84e 100644
--- a/src/libcore/num/wrapping.rs
+++ b/src/libcore/num/wrapping.rs
@@ -292,6 +292,12 @@ wrapping_impl! { usize u8 u16 u32 u64 isize i8 i16 i32 i64 }
 mod shift_max {
     #![allow(non_upper_case_globals)]
 
+    #[cfg(target_pointer_width = "16")]
+    mod platform {
+        pub const usize: u32 = super::u16;
+        pub const isize: u32 = super::i16;
+    }
+
     #[cfg(target_pointer_width = "32")]
     mod platform {
         pub const usize: u32 = super::u32;