From 0ac363e203c7ea830b095fe353c00ad9cfc0aa3b Mon Sep 17 00:00:00 2001
From: taitep <taitep@taitep.se>
Date: Mon, 22 Dec 2025 22:48:57 +0100
Subject: [PATCH] Implement LW

---
 src/instructions.rs         |  1 +
 src/instructions/rvi/mem.rs | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/src/instructions.rs b/src/instructions.rs
index 4a7a627..72ce3d2 100644
--- a/src/instructions.rs
+++ b/src/instructions.rs
@@ -45,6 +45,7 @@ pub(crate) fn find_and_exec(instr: Instruction, core: &mut Core) -> Option<Instr
             0b000 => Some(rvi::lb(core, instr)),
             0b100 => Some(rvi::lbu(core, instr)),
             0b001 => Some(rvi::lh(core, instr)),
+            0b010 => Some(rvi::lw(core, instr)),
             0b011 => Some(rvi::ld(core, instr)),
             _ => None,
         },
diff --git a/src/instructions/rvi/mem.rs b/src/instructions/rvi/mem.rs
index c57e079..d065e8d 100644
--- a/src/instructions/rvi/mem.rs
+++ b/src/instructions/rvi/mem.rs
@@ -66,6 +66,26 @@ pub fn sw(core: &mut Core, instr: Instruction) -> InstructionResult {
     }
 }
 
+pub fn lw(core: &mut Core, instr: Instruction) -> InstructionResult {
+    let addr = core.reg_read(instr.rs1()).wrapping_add(instr.imm_i());
+
+    if !addr.is_multiple_of(std::mem::size_of::<Word>() as Addr) {
+        return InstructionResult::Exception(());
+    }
+
+    let page = (addr / 4096) as PageNum;
+    let offset = (addr / 4 & ((4096 / 4 as Addr) - 1)) as u16;
+
+    match core.mem.read_word(page, offset) {
+        Ok(x) => {
+            core.reg_write(instr.rd(), x as i32 as i64 as DWord);
+            core.advance_pc();
+            InstructionResult::Normal
+        }
+        Err(_) => InstructionResult::Exception(()),
+    }
+}
+
 pub fn lh(core: &mut Core, instr: Instruction) -> InstructionResult {
     let addr = core.reg_read(instr.rs1()).wrapping_add(instr.imm_i());