Merge pull request #12 from rbartlensky/fix-instruction-encoding-decoding

Fix instruction encoding and decoding.

Author: ltratt

luacompiler/build.rs

@@ -2,11 +2,14 @@ extern crate lrlex;
 extern crate lrpar;
 
 use lrlex::LexerBuilder;
+use lrpar::ActionKind;
 use lrpar::CTParserBuilder;
 
 fn main() -> Result<(), Box<std::error::Error>> {
-    let lex_rule_ids_map =
-        CTParserBuilder::<u8>::new_with_storaget().process_file_in_src("lua5_3/lua5_3.y")?;
+    let mut ct = CTParserBuilder::<u8>::new_with_storaget()
+        .error_on_conflicts(false)
+        .action_kind(ActionKind::GenericParseTree);
+    let lex_rule_ids_map = ct.process_file_in_src("lua5_3/lua5_3.y")?;
     LexerBuilder::new()
         .rule_ids_map(lex_rule_ids_map)
         .process_file_in_src("lua5_3/lua5_3.l")?;

luacompiler/src/lib/bytecode/instructions.rs

@@ -1,4 +1,4 @@
-const MASK: u32 = 0x000F;
+const MASK: u32 = 0x000000FF;
 
 /// Get the opcode of an instruction
 pub fn opcode(instr: u32) -> u8 {
@@ -7,22 +7,22 @@ pub fn opcode(instr: u32) -> u8 {
 
 /// Get the first argument of an instruction.
 pub fn first_arg(instr: u32) -> u8 {
-    ((instr >> 4) & MASK) as u8
+    ((instr >> 8) & MASK) as u8
 }
 
 /// Get the second argument of an instruction.
 pub fn second_arg(instr: u32) -> u8 {
-    ((instr >> 8) & MASK) as u8
+    ((instr >> 16) & MASK) as u8
 }
 
 /// Get the third argument of an instruction.
 pub fn third_arg(instr: u32) -> u8 {
-    ((instr >> 12) & MASK) as u8
+    ((instr >> 24) & MASK) as u8
 }
 
 /// Create an instruction with the given opcode and arguments.
 pub fn make_instr(opcode: Opcode, arg1: u8, arg2: u8, arg3: u8) -> u32 {
-    opcode as u32 + ((arg1 as u32) << 4) + ((arg2 as u32) << 8) + ((arg3 as u32) << 12)
+    opcode as u32 + ((arg1 as u32) << 8) + ((arg2 as u32) << 16) + ((arg3 as u32) << 24)
 }
 
 /// Represents a high level instruction whose operands have a size of usize.
@@ -58,3 +58,23 @@ pub enum Opcode {
     FDIV = 9, // R(1) = R(2) // R(3)
     EXP = 10, // R(1) = R(2) ^ R(3)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn encoding_and_decoding_works() {
+        for i in 0..=255 {
+            for j in 0..=255 {
+                for k in 0..=255 {
+                    let instr = make_instr(Opcode::MOV, i, j, k);
+                    assert_eq!(opcode(instr), Opcode::MOV as u8);
+                    assert_eq!(first_arg(instr), i);
+                    assert_eq!(second_arg(instr), j);
+                    assert_eq!(third_arg(instr), k);
+                }
+            }
+        }
+    }
+}