From df8418119ca732babce256aef46b6f2175be62cf Mon Sep 17 00:00:00 2001
From: mrmr1993 <mr_1993@hotmail.co.uk>
Date: Tue, 5 Dec 2023 23:40:02 +0000
Subject: [PATCH] Implement `slti`

---
 optimism/src/mips/interpreter.rs | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/optimism/src/mips/interpreter.rs b/optimism/src/mips/interpreter.rs
index 797d08b320..f3b7b83085 100644
--- a/optimism/src/mips/interpreter.rs
+++ b/optimism/src/mips/interpreter.rs
@@ -1001,7 +1001,19 @@ pub fn interpret_itype<Env: InterpreterEnv>(env: &mut Env, instr: ITypeInstructi
             // REMOVEME: when all itype instructions are implemented.
             return;
         }
-        ITypeInstruction::SetLessThanImmediate => (),
+        ITypeInstruction::SetLessThanImmediate => {
+            let rs = env.read_register(&rs);
+            let immediate = env.sign_extend(&immediate, 16);
+            let res = {
+                // FIXME: Constrain
+                let pos = env.alloc_scratch();
+                unsafe { env.test_less_than_signed(&rs, &immediate, pos) }
+            };
+            env.write_register(&rt, res);
+            env.set_instruction_pointer(next_instruction_pointer.clone());
+            env.set_next_instruction_pointer(next_instruction_pointer + Env::constant(4u32));
+            return;
+        }
         ITypeInstruction::SetLessThanImmediateUnsigned => {
             let rs = env.read_register(&rs);
             let immediate = env.sign_extend(&immediate, 16);