Start the garbage collector.

I don't think we finished it, but I wrote this code a while ago and I'm
just trying to get it committed.

1 files changed, 33 insertions, 0 deletions

diff --git a/bytecode/src/stack.rs b/bytecode/src/stack.rs
new file mode 100644
index 0000000..66d3f7c
--- /dev/null
+++ b/bytecode/src/stack.rs
@@ -0,0 +1,33 @@
+struct Stack {
+    v: Vec<u64>,
+}
+
+impl Stack {
+    fn pop(&mut self) -> Result<u64, String> {
+        self.v.pop().ok_or(String::from("stack underflow"))
+    }
+
+    fn pop_int(&mut self) -> Result<i64, String> {
+        Ok(self.pop()? as i64 >> 1)
+    }
+
+    fn push_int(&mut self, i: i64) {
+        self.v.push((i as u64) << 1 | 1);
+    }
+
+    fn pop_pointer(&mut self) -> Result<Pointer, String> {
+        Ok(Pointer::from_bytes(self.pop()?))
+    }
+
+    fn push_pointer(&mut self, p: Pointer) {
+        self.v.push(p.bytes());
+    }
+
+    fn pop_usize(&mut self) -> Result<usize, String> {
+        Ok(usize::try_from(self.pop()?).unwrap() >> 1)
+    }
+
+    fn push_usize(&mut self, p: usize) {
+        self.v.push(u64::try_from(p).unwrap() << 1 | 1);
+    }
+}