From 209e44ae64a1af10063b1c589377e136c644ec8f Mon Sep 17 00:00:00 2001
From: taitep <taitep@taitep.se>
Date: Sun, 21 Dec 2025 21:00:25 +0100
Subject: [PATCH] Implement LD and BNE

---
 src/instructions.rs     |  2 ++
 src/instructions/rvi.rs | 30 ++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/src/instructions.rs b/src/instructions.rs
index e72dfb5..a2edc53 100644
--- a/src/instructions.rs
+++ b/src/instructions.rs
@@ -35,11 +35,13 @@ pub(crate) fn find_and_exec(instr: Instruction, core: &mut Core) -> Option<Instr
             // LOAD
             0b000 => Some(rvi::lb(core, instr)),
             0b100 => Some(rvi::lbu(core, instr)),
+            0b011 => Some(rvi::ld(core, instr)),
             _ => None,
         },
         0b11000 => match instr.funct3() {
             // BRANCH
             0b000 => Some(rvi::beq(core, instr)),
+            0b001 => Some(rvi::bne(core, instr)),
             _ => None,
         },
         0b01101 => Some(rvi::lui(core, instr)),
diff --git a/src/instructions/rvi.rs b/src/instructions/rvi.rs
index 239ae98..f182e88 100644
--- a/src/instructions/rvi.rs
+++ b/src/instructions/rvi.rs
@@ -61,6 +61,26 @@ pub fn sd(core: &mut Core, instr: Instruction) -> InstructionResult {
     }
 }
 
+pub fn ld(core: &mut Core, instr: Instruction) -> InstructionResult {
+    let addr = core.reg_read(instr.rs1()).wrapping_add(instr.imm_s());
+
+    if !addr.is_multiple_of(std::mem::size_of::<DWord>() as Addr) {
+        return InstructionResult::Exception(());
+    }
+
+    let page = (addr / 4096) as PageNum;
+    let offset = (addr / 8 & ((4096 / 8 as Addr) - 1)) as u16;
+
+    match core.mem.read_dword(page, offset) {
+        Ok(x) => {
+            core.reg_write(instr.rd(), x);
+            core.advance_pc();
+            InstructionResult::Normal
+        }
+        Err(_) => InstructionResult::Exception(()),
+    }
+}
+
 pub fn sb(core: &mut Core, instr: Instruction) -> InstructionResult {
     let addr = core.reg_read(instr.rs1()).wrapping_add(instr.imm_s());
 
@@ -145,6 +165,16 @@ pub fn beq(core: &mut Core, instr: Instruction) -> InstructionResult {
     InstructionResult::Normal
 }
 
+pub fn bne(core: &mut Core, instr: Instruction) -> InstructionResult {
+    if core.reg_read(instr.rs1()) != core.reg_read(instr.rs2()) {
+        core.pc = core.pc.wrapping_add(instr.imm_b());
+    } else {
+        core.advance_pc();
+    }
+
+    InstructionResult::Normal
+}
+
 pub fn slli(core: &mut Core, instr: Instruction) -> InstructionResult {
     core.reg_write(instr.rd(), core.reg_read(instr.rs1()) << instr.imm_shamt());