Further work on implementing support for cheats

2026-06-02 01:06:50 +02:00 · 2026-02-21 19:30:03 +01:00
parent 3300c5277c
commit 83046e2cc2
11 changed files with 286 additions and 15 deletions
--- a/arm9/source/patches/arm7/cheats/CheatEnginePatch.cpp
+++ b/arm9/source/patches/arm7/cheats/CheatEnginePatch.cpp
@@ -0,0 +1,125 @@
+#include "common.h"
+#include "CheatEnginePatchCode.h"
+#include "CheatEnginePatch.h"
+
+// sdk2-4
+static const u32 sVBlankIntrPatternArm0[] = { 0xE92D4000u, 0xE24DD004u, 0xE59F0018u, 0xE5900000u };
+static const u32 sVBlankIntrPatternArm1[] = { 0xE92D4008u, 0xE59F0014u, 0xE5900000u, 0xE3500000u };
+static const u32 sVBlankIntrPatternThumb0[] = { 0x00000000u, 0xB081B500u, 0x68004804u, 0xD0012800u }; // +4
+static const u32 sVBlankIntrPatternThumb1[] = { 0x46C04770u, 0x027FFE1Du, 0x4804B508u, 0x28006800u }; // +8
+
+bool CheatEnginePatch::FindPatchTarget(PatchContext& patchContext)
+{
+    _vblankIrqHandler = patchContext.FindPattern32(sVBlankIntrPatternArm0, sizeof(sVBlankIntrPatternArm0));
+    if (_vblankIrqHandler)
+    {
+        _foundPattern = sVBlankIntrPatternArm0;
+    }
+    if (!_vblankIrqHandler)
+    {
+        _vblankIrqHandler = patchContext.FindPattern32(sVBlankIntrPatternArm1, sizeof(sVBlankIntrPatternArm1));
+        if (_vblankIrqHandler)
+        {
+            _foundPattern = sVBlankIntrPatternArm1;
+        }
+    }
+    if (!_vblankIrqHandler)
+    {
+        _vblankIrqHandler = patchContext.FindPattern32(sVBlankIntrPatternThumb0, sizeof(sVBlankIntrPatternThumb0));
+        if (_vblankIrqHandler)
+        {
+            _foundPattern = sVBlankIntrPatternThumb0;
+            _vblankIrqHandler += 1;
+        }
+    }
+    if (!_vblankIrqHandler)
+    {
+        _vblankIrqHandler = patchContext.FindPattern32(sVBlankIntrPatternThumb1, sizeof(sVBlankIntrPatternThumb1));
+        if (_vblankIrqHandler)
+        {
+            _foundPattern = sVBlankIntrPatternThumb1;
+            _vblankIrqHandler += 2;
+        }
+    }
+
+    if (_vblankIrqHandler)
+    {
+        LOG_DEBUG("ARM7 VBlankIntr found at 0x%p\n", _vblankIrqHandler);
+    }
+
+    return _vblankIrqHandler != nullptr;
+}
+
+void CheatEnginePatch::ApplyPatch(PatchContext& patchContext)
+{
+    if (!_vblankIrqHandler || !_cheats)
+        return;
+
+    auto cheatEnginePatchCode = patchContext.GetPatchCodeCollection().AddUniquePatchCode<CheatEnginePatchCode>
+    (
+        patchContext.GetPatchHeap(),
+        _cheats
+    );
+
+    if (_foundPattern == sVBlankIntrPatternArm0)
+    {
+        // push {lr}
+        // sub sp, sp, #4
+        // ldr r0,=
+        // ldr r0, [r0]
+        // cmp r0, #0
+        // beq 1f
+        // bl
+        // 1:
+        // add sp, sp, #4
+        // pop {lr}
+        // bx lr
+        _vblankIrqHandler[7] = 0xE59F0000; // ldr r0,= address
+        _vblankIrqHandler[8] = 0xE12FFF10; // bx r0
+        _vblankIrqHandler[9] = (u32)cheatEnginePatchCode->GetCheatEngineFunction(); // address
+    }
+    else if (_foundPattern == sVBlankIntrPatternArm1)
+    {
+        // push {r3,lr}
+        // ldr r0,=
+        // ldr r0, [r0]
+        // cmp r0, #0
+        // beq 1f
+        // bl
+        // 1:
+        // pop {r3,lr}
+        // bx lr
+    }
+    else if (_foundPattern == sVBlankIntrPatternThumb0)
+    {
+        // push {lr}
+        // sub sp, sp, #4
+        // ldr r0,=
+        // ldr r0, [r0]
+        // cmp r0, #0
+        // beq 1f
+        // bl
+        // 1:
+        // add sp, sp, #4
+        // pop {r3}
+        // bx r3
+        // nop
+    }
+    else if (_foundPattern == sVBlankIntrPatternThumb1)
+    {
+        // push {r3,lr}
+        // ldr r0,=
+        // ldr r0, [r0]
+        // cmp r0, #0
+        // beq 1f
+        // bl
+        // 1:
+        // pop {r3}
+        // pop {r3}
+        // bx r3
+    }
+    else
+    {
+        LOG_ERROR("ARM7 VBlankIntr signature not implemented\n");
+    }
+}