From 6c39a5eef270e160f9954dc8eac99ce53e8423c9 Mon Sep 17 00:00:00 2001
From: taitep <taitep@taitep.se>
Date: Sun, 21 Dec 2025 19:36:25 +0100
Subject: [PATCH] Implement JALR, fix JAL, change how some stuff in
 instructions.rs is expressed

---
 src/instructions.rs     |  9 +++------
 src/instructions/rvi.rs | 14 ++++++++++----
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/instructions.rs b/src/instructions.rs
index bf942ee..e72dfb5 100644
--- a/src/instructions.rs
+++ b/src/instructions.rs
@@ -16,11 +16,7 @@ pub(crate) fn find_and_exec(instr: Instruction, core: &mut Core) -> Option<Instr
         0b00100 => match instr.funct3() {
             // OP_IMM
             0b000 => Some(rvi::addi(core, instr)),
-            0b001 => match instr.funct6() {
-                // left-shift immediate
-                0b000000 => Some(rvi::slli(core, instr)),
-                _ => None,
-            },
+            0b001 => (instr.funct6() == 0).then(|| rvi::slli(core, instr)),
             0b111 => Some(rvi::andi(core, instr)),
             _ => None,
         },
@@ -47,8 +43,9 @@ pub(crate) fn find_and_exec(instr: Instruction, core: &mut Core) -> Option<Instr
             _ => None,
         },
         0b01101 => Some(rvi::lui(core, instr)),
-        0b11011 => Some(rvi::jal(core, instr)),
         0b00101 => Some(rvi::auipc(core, instr)),
+        0b11011 => Some(rvi::jal(core, instr)),
+        0b11001 => (instr.funct3() == 0).then(|| rvi::jalr(core, instr)),
         _ => None,
     }
 }
diff --git a/src/instructions/rvi.rs b/src/instructions/rvi.rs
index 5c06b62..239ae98 100644
--- a/src/instructions/rvi.rs
+++ b/src/instructions/rvi.rs
@@ -117,15 +117,21 @@ pub fn lui(core: &mut Core, instr: Instruction) -> InstructionResult {
     InstructionResult::Normal
 }
 
+pub fn auipc(core: &mut Core, instr: Instruction) -> InstructionResult {
+    core.reg_write(instr.rd(), core.pc.wrapping_add(instr.imm_u()));
+    core.advance_pc();
+    InstructionResult::Normal
+}
+
 pub fn jal(core: &mut Core, instr: Instruction) -> InstructionResult {
-    core.reg_write(instr.rd(), core.pc);
+    core.reg_write(instr.rd(), core.pc.wrapping_add(4));
     core.pc = core.pc.wrapping_add(instr.imm_j());
     InstructionResult::Normal
 }
 
-pub fn auipc(core: &mut Core, instr: Instruction) -> InstructionResult {
-    core.reg_write(instr.rd(), core.pc.wrapping_add(instr.imm_u()));
-    core.advance_pc();
+pub fn jalr(core: &mut Core, instr: Instruction) -> InstructionResult {
+    core.reg_write(instr.rd(), core.pc.wrapping_add(4));
+    core.pc = core.reg_read(instr.rs1()).wrapping_add(instr.imm_i());
     InstructionResult::Normal
 }