From 32bdfd563dbcb262e5417bbb5a2afccbd15b803b Mon Sep 17 00:00:00 2001
From: Nathan Lee <me@nwlee.tech>
Date: Wed, 3 Jun 2026 20:36:08 -0500
Subject: finish S and I type RV32I instructions

---
 src/main.rs | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 77685a4..8aacb63 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -44,10 +44,6 @@ fn main() {
             if let Ok(sh_name) = str_tab.get(header.sh_name as usize)
                 && sh_name == ".text"
             {
-                let (sh_data, _) = elf
-                    .section_data(&header)
-                    .expect("Unable to get section data");
-
                 pc = header.sh_addr as u32;
             }
         }
@@ -163,10 +159,12 @@ fn handle_instruction(memory: &mut [u8], registers: &mut [u32], pc: u32) {
                     let number: u32 = slice.iter().fold(0u32, |acc, &n| (acc << 8) | n as u32);
                     registers[rd] = number; // lw
                 }
-                4 => {
-                    println!("lbu {} {} {}", ABI[rd], ABI[rs1], imm & 0xFF);
-                }
-                5 => println!("lhu {} {} {}", ABI[rd], ABI[rs1], imm & 0xFFFF),
+                4 => registers[rd] = memory[(registers[rs1] + imm) as usize] as u32, // lbu
+                5 => {
+                    let low = memory[(registers[rs1] + imm) as usize];
+                    let high = memory[(registers[rs1] + imm + 1) as usize];
+                    registers[rd] = ((high as u16) << 8 | low as u16) as u32; // lhu
+                },
                 _ => panic!("Illegal instruction: {:x}", word),
             }
         }
@@ -180,9 +178,17 @@ fn handle_instruction(memory: &mut [u8], registers: &mut [u32], pc: u32) {
             let imm = (imm_high << 5) | imm_low;
 
             match f3 {
-                0 => println!("sb {} {} {}", ABI[rs1], ABI[rs2], imm & 0xFF),
-                1 => println!("sh {} {} {}", ABI[rs1], ABI[rs2], imm & 0xFFFF),
-                2 => println!("sw {} {} {}", ABI[rs1], ABI[rs2], imm & 0xFFFFFF),
+                0 => memory[(registers[rs1] + imm) as usize] = registers[rs2] as u8, // sb
+                1 => {
+                    let halfword = registers[rs2] & 0xFFFF;
+                    let index = (registers[rs1] + imm) as usize;
+                    memory[index] = (halfword & 0xFF) as u8;
+                    memory[index + 1] = (halfword >> 8) as u8;
+                }, // sh
+                2 => {
+                    let index = (registers[rs1] + imm) as usize;
+                    memory[index..index + 4].copy_from_slice(&registers[rs2].to_le_bytes()); // sw
+                },
                 _ => panic!("Illegal instruction: {:x}", word),
             };
         }
@@ -192,8 +198,7 @@ fn handle_instruction(memory: &mut [u8], registers: &mut [u32], pc: u32) {
         0b0110111 => {
             let imm = word >> 12;
             let rd = ((word >> 7) & 0b11111) as usize;
-            println!("lui {} {}", rd, imm as i32);
-            registers[rd] = imm << 12;
+            registers[rd] = imm << 12; // lui
         }
         0b0010111 => {
             let imm = word >> 12;
-- 
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