@@ -9,6 +9,7 @@ - Customizable autofire speed
  - Ability to set default Game Boy model
  - Map viewer
  - Automatic cheat loading and saving
+ - GameShark and Action Replay button support
 Bugfixes:
  - GB Audio: Make audio unsigned with bias (fixes mgba.io/i/749)
  - GB Serialize: Fix audio state loading

@@ -30,7 +30,8 @@ CHEAT_IF_ULT,
 	CHEAT_IF_UGT,
 	CHEAT_IF_AND,
 	CHEAT_IF_LAND,
-	CHEAT_IF_NAND
+	CHEAT_IF_NAND,
+	CHEAT_IF_BUTTON,
 };
 
 struct mCheat {
@@ -80,6 +81,7 @@ struct mCheatSet* (*createSet)(struct mCheatDevice*, const char* name);
 
 	struct mCheatSets cheats;
 	bool autosave;
+	bool buttonDown;
 };
 
 struct VFile;
@@ -102,6 +104,7 @@ bool mCheatSaveFile(struct mCheatDevice*, struct VFile*);
 void mCheatAutosave(struct mCheatDevice*);
 
 void mCheatRefresh(struct mCheatDevice*, struct mCheatSet*);
+void mCheatPressButton(struct mCheatDevice*, bool down);
 
 CXX_GUARD_END
 

@@ -52,6 +52,7 @@ device->d.id = M_CHEAT_DEVICE_ID;
 	device->d.init = mCheatDeviceInit;
 	device->d.deinit = mCheatDeviceDeinit;
 	device->autosave = false;
+	device->buttonDown = false;
 	mCheatSetsInit(&device->cheats, 4);
 }
 
@@ -360,6 +361,12 @@ conditionRemaining = cheat->repeat;
 				negativeConditionRemaining = cheat->negativeRepeat;
 				operationsRemaining = 1;
 				break;
+			case CHEAT_IF_BUTTON:
+				condition = device->buttonDown;
+				conditionRemaining = cheat->repeat;
+				negativeConditionRemaining = cheat->negativeRepeat;
+				operationsRemaining = 1;
+				break;
 			}
 
 			if (performAssignment) {
@@ -382,6 +389,10 @@ elseLoc = i + conditionRemaining;
 			endLoc = elseLoc + negativeConditionRemaining;
 		}
 	}
+}
+
+void mCheatPressButton(struct mCheatDevice* device, bool down) {
+	device->buttonDown = down;
 }
 
 void mCheatDeviceInit(void* cpu, struct mCPUComponent* component) {

@@ -154,9 +154,32 @@ cheats->romPatches[0].applied = false;
 		cheats->romPatches[0].exists = true;
 		return true;
 	case GSA_BUTTON:
-		// TODO: Implement button
-		mLOG(CHEATS, STUB, "GameShark button unimplemented");
-		return false;
+		switch (op1 & 0x00F00000) {
+		case 0x00100000:
+			cheat = mCheatListAppend(&cheats->d.list);
+			cheat->type = CHEAT_IF_BUTTON;
+			cheat->repeat = 1;
+			cheat->negativeRepeat = 0;
+			cheat = mCheatListAppend(&cheats->d.list);
+			cheat->type = CHEAT_ASSIGN;
+			cheat->width = 1;
+			cheat->address = op1 & 0x0F0FFFFF;
+			break;
+		case 0x00200000:
+			cheat = mCheatListAppend(&cheats->d.list);
+			cheat->type = CHEAT_IF_BUTTON;
+			cheat->repeat = 1;
+			cheat->negativeRepeat = 0;
+			cheat = mCheatListAppend(&cheats->d.list);
+			cheat->type = CHEAT_ASSIGN;
+			cheat->width = 2;
+			cheat->address = op1 & 0x0F0FFFFF;
+			break;
+		default:
+			mLOG(CHEATS, STUB, "GameShark button type unimplemented");
+			return false;
+		}
+		break;
 	case GSA_IF_EQ:
 		if (op1 == 0xDEADFACE) {
 			GBACheatReseedGameShark(cheats->gsaSeeds, op2, _gsa1T1, _gsa1T2);

@@ -144,13 +144,41 @@ struct mCheat* cheat;
 	switch (op2 & 0xFF000000) {
 	case PAR3_OTHER_SLOWDOWN:
 		// TODO: Slowdown
+		mLOG(CHEATS, STUB, "Unimplemented PARv3 slowdown");
 		return false;
 	case PAR3_OTHER_BUTTON_1:
+		cheat = mCheatListAppend(&cheats->d.list);
+		cheat->type = CHEAT_IF_BUTTON;
+		cheat->repeat = 1;
+		cheat->negativeRepeat = 0;
+		cheat = mCheatListAppend(&cheats->d.list);
+		cheat->type = CHEAT_ASSIGN;
+		cheat->width = 1;
+		cheat->address = _parAddr(op2);
+		cheats->incompleteCheat = mCheatListIndex(&cheats->d.list, cheat);
+		break;
 	case PAR3_OTHER_BUTTON_2:
+		cheat = mCheatListAppend(&cheats->d.list);
+		cheat->type = CHEAT_IF_BUTTON;
+		cheat->repeat = 1;
+		cheat->negativeRepeat = 0;
+		cheat = mCheatListAppend(&cheats->d.list);
+		cheat->type = CHEAT_ASSIGN;
+		cheat->width = 2;
+		cheat->address = _parAddr(op2);
+		cheats->incompleteCheat = mCheatListIndex(&cheats->d.list, cheat);
+		break;
 	case PAR3_OTHER_BUTTON_4:
-		// TODO: Button
-		mLOG(CHEATS, STUB, "GameShark button unimplemented");
-		return false;
+		cheat = mCheatListAppend(&cheats->d.list);
+		cheat->type = CHEAT_IF_BUTTON;
+		cheat->repeat = 1;
+		cheat->negativeRepeat = 0;
+		cheat = mCheatListAppend(&cheats->d.list);
+		cheat->type = CHEAT_ASSIGN;
+		cheat->width = 4;
+		cheat->address = _parAddr(op2);
+		cheats->incompleteCheat = mCheatListIndex(&cheats->d.list, cheat);
+		break;
 	// TODO: Fix overriding existing patches
 	case PAR3_OTHER_PATCH_1:
 		cheats->romPatches[0].address = BASE_CART0 | ((op2 & 0xFFFFFF) << 1);

@@ -1016,6 +1016,34 @@ assert_int_equal(core->rawRead8(core, 0x03000005, -1), 0x51);
 	assert_int_equal(core->rawRead8(core, 0x03000006, -1), 0x62);
 	assert_int_equal(core->rawRead8(core, 0x03000007, -1), 0x71);
 	assert_int_equal(core->rawRead8(core, 0x03000008, -1), 0x82);
+	set->deinit(set);
+}
+
+M_TEST_DEFINE(doPARv3IfButton) {
+	struct mCore* core = *state;
+	struct mCheatDevice* device = core->cheatDevice(core);
+	assert_non_null(device);
+	struct mCheatSet* set = device->createSet(device, NULL);
+	assert_non_null(set);
+	GBACheatSetGameSharkVersion((struct GBACheatSet*) set, GBA_GS_PARV3_RAW);
+	assert_true(set->addLine(set, "00000000 10300000", GBA_CHEAT_PRO_ACTION_REPLAY));
+	assert_true(set->addLine(set, "00000001 00000000", GBA_CHEAT_PRO_ACTION_REPLAY));
+
+	core->reset(core);
+	assert_int_equal(core->rawRead8(core, 0x03000000, -1), 0);
+
+	mCheatRefresh(device, set);
+	assert_int_equal(core->rawRead8(core, 0x03000000, -1), 0);
+
+	mCheatPressButton(device, true);
+	mCheatRefresh(device, set);
+	assert_int_equal(core->rawRead8(core, 0x03000000, -1), 0);
+
+	mCheatPressButton(device, false);
+	core->rawWrite8(core, 0x03000000, -1, 0);
+	mCheatRefresh(device, set);
+	assert_int_equal(core->rawRead8(core, 0x03000000, -1), 0);
+	set->deinit(set);
 }
 
 M_TEST_SUITE_DEFINE_SETUP_TEARDOWN(GBACheats,
@@ -1038,4 +1066,5 @@ cmocka_unit_test(doPARv3IfXElsexXElse),
 	cmocka_unit_test(doPARv3IfXContain1),
 	cmocka_unit_test(doPARv3IfXContain1Else),
 	cmocka_unit_test(doPARv3IfXElseContain1),
-	cmocka_unit_test(doPARv3IfXContain1ElseContain1))
+	cmocka_unit_test(doPARv3IfXContain1ElseContain1),
+	cmocka_unit_test(doPARv3IfButton))

@@ -52,6 +52,7 @@ #include "TileView.h"
 #include "VideoView.h"
 
 #include <mgba/core/version.h>
+#include <mgba/core/cheats.h>
 #ifdef M_CORE_GB
 #include <mgba/internal/gb/gb.h>
 #include <mgba/internal/gb/video.h>
@@ -1601,6 +1602,16 @@ QAction* exitFullScreen = new QAction(tr("Exit fullscreen"), frameMenu);
 	connect(exitFullScreen, &QAction::triggered, this, &Window::exitFullScreen);
 	exitFullScreen->setShortcut(QKeySequence("Esc"));
 	addHiddenAction(frameMenu, exitFullScreen, "exitFullScreen");
+
+	m_shortcutController->addFunctions(toolsMenu, [this]() {
+		if (m_controller) {
+			mCheatPressButton(m_controller->cheatDevice(), true);
+		}
+	}, [this]() {
+		if (m_controller) {
+			mCheatPressButton(m_controller->cheatDevice(), false);
+		}
+	}, QKeySequence(Qt::Key_Apostrophe), tr("GameShark Button (held)"), "holdGSButton");
 
 	QMenu* autofireMenu = new QMenu(tr("Autofire"), this);
 	m_shortcutController->addMenu(autofireMenu);