From 9e6b1219189ac5e2767dbb37cbea93ea7de2bc0e Mon Sep 17 00:00:00 2001
From: Amneesh Singh <natto@weirdnatto.in>
Date: Tue, 11 Jun 2024 23:22:34 +0530
Subject: [PATCH] cpu/thumb: fix pc relative load

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>
---
 src/cpu/thumb/exec.cc   | 1 +
 tests/cpu/thumb/exec.cc | 6 +++---
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/cpu/thumb/exec.cc b/src/cpu/thumb/exec.cc
index b8bf328..47b92fe 100644
--- a/src/cpu/thumb/exec.cc
+++ b/src/cpu/thumb/exec.cc
@@ -189,6 +189,7 @@ Instruction::exec(Cpu& cpu) {
         },
         [&cpu](PcRelativeLoad& data) {
             uint32_t pc = cpu.pc;
+            rst_bit(pc, 0);
             rst_bit(pc, 1);
 
             cpu.gpr[data.rd] = cpu.bus->read_word(pc + data.word);
diff --git a/tests/cpu/thumb/exec.cc b/tests/cpu/thumb/exec.cc
index 6227966..ac68cb4 100644
--- a/tests/cpu/thumb/exec.cc
+++ b/tests/cpu/thumb/exec.cc
@@ -1,6 +1,5 @@
 #include "cpu/cpu-fixture.hh"
 #include "cpu/thumb/instruction.hh"
-#include "util/bits.hh"
 #include <catch2/catch_test_macros.hpp>
 
 using namespace matar;
@@ -531,8 +530,9 @@ TEST_CASE_METHOD(CpuFixture, "PC Relative Load", TAG) {
     InstructionData data = PcRelativeLoad{ .word = 0x578, .rd = 0 };
 
     setr(15, 0x3003FD5);
-    // 0x3003FD5 + 0x578
-    bus.write_word(0x300454D, 489753492);
+    // resetting bit 0 for 0x3003FD5, we get 0x3003FD4
+    // 0x3003FD4 + 0x578
+    bus.write_word(0x300454C, 489753492);
 
     CHECK(getr(0) == 0);
     exec(data);