From 783706193b97d27a51d8b040319fa1ef042dc408 Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Sat, 12 Feb 2022 03:13:38 -0400
Subject: [PATCH] fix: properly decode format 11 instructions

---
 src/cpu.zig                           | 2 +-
 src/cpu/thumb/block_data_transfer.zig | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/cpu.zig b/src/cpu.zig
index 688bae8..1cf426e 100644
--- a/src/cpu.zig
+++ b/src/cpu.zig
@@ -496,7 +496,7 @@ fn thumbPopulate() [0x400]ThumbInstrFn {
                     },
                     0b001 => blk: {
                         const L = i >> 5 & 1 == 1;
-                        const rd = i >> 2 & 0x3;
+                        const rd = i >> 2 & 0x7;
                         break :blk format11(L, rd);
                     },
                     0b010 => blk: {
diff --git a/src/cpu/thumb/block_data_transfer.zig b/src/cpu/thumb/block_data_transfer.zig
index 975623d..62789de 100644
--- a/src/cpu/thumb/block_data_transfer.zig
+++ b/src/cpu/thumb/block_data_transfer.zig
@@ -5,12 +5,12 @@ const InstrFn = @import("../../cpu.zig").ThumbInstrFn;
 pub fn format14(comptime L: bool, comptime R: bool) InstrFn {
     return struct {
         fn inner(cpu: *Arm7tdmi, bus: *Bus, opcode: u16) void {
-            const count = countRlist(opcode);
-            const start = cpu.r[13] - if (!L) 4 * (@boolToInt(R) + count) else 0;
+            const count = @boolToInt(R) + countRlist(opcode);
+            const start = cpu.r[13] - if (!L) count * 4 else 0;
 
             var end = cpu.r[13];
             if (L) {
-                end += 4 * (@boolToInt(R) + count);
+                end += count * 4;
             } else {
                 end -= 4;
             }
@@ -40,7 +40,7 @@ pub fn format14(comptime L: bool, comptime R: bool) InstrFn {
                 address += 4;
             }
 
-            cpu.r[13] = if (L) end else cpu.r[13] - 4 * (@boolToInt(R) + count);
+            cpu.r[13] = if (L) end else start;
         }
     }.inner;
 }