GBA Peripherals: Start implementing BattleChip Gate

include/mgba/gba/interface.h

@@ -11,6 +11,7 @@
 CXX_GUARD_START
 
 #include <mgba/core/interface.h>
+#include <mgba/core/timing.h>
 
 enum GBASIOMode {
 	SIO_NORMAL_8 = 0,
@@ -36,7 +37,8 @@ struct GBAVideoRenderer;
 extern const int GBA_LUX_LEVELS[10];
 
 enum {
-	mPERIPH_GBA_LUMINANCE = 0x1000
+	mPERIPH_GBA_LUMINANCE = 0x1000,
+	mPERIPH_GBA_BATTLECHIP_GATE,
 };
 
 struct GBALuminanceSource {
@@ -58,6 +60,14 @@ struct GBASIODriver {
 void GBASIOJOYCreate(struct GBASIODriver* sio);
 int GBASIOJOYSendCommand(struct GBASIODriver* sio, enum GBASIOJOYCommand command, uint8_t* data);
 
+struct GBASIOBattlechipGate {
+	struct GBASIODriver d;
+	struct mTimingEvent event;
+	uint16_t chipId;
+	int32_t index;
+};
+
+void GBASIOBattlechipGateCreate(struct GBASIOBattlechipGate*);
 
 CXX_GUARD_END
 

src/gba/core.c

@@ -533,6 +533,9 @@ static void _GBACoreSetPeripheral(struct mCore* core, int type, void* periph) {
 	case mPERIPH_GBA_LUMINANCE:
 		gba->luminanceSource = periph;
 		break;
+	case mPERIPH_GBA_BATTLECHIP_GATE:
+		GBASIOSetDriver(&gba->sio, periph, SIO_MULTI);
+		break;
 	default:
 		return;
 	}

src/gba/extra/battlechip.c

@@ -0,0 +1,136 @@
+/* Copyright (c) 2013-2018 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include <mgba/gba/interface.h>
+
+#include <mgba/internal/gba/gba.h>
+#include <mgba/internal/gba/io.h>
+#include <mgba/internal/gba/sio.h>
+
+mLOG_DECLARE_CATEGORY(GBA_BATTLECHIP);
+mLOG_DEFINE_CATEGORY(GBA_BATTLECHIP, "GBA BattleChip Gate", "gba.battlechip");
+
+enum {
+	BATTLECHIP_INDEX_HANDSHAKE_0 = 0,
+	BATTLECHIP_INDEX_HANDSHAKE_1 = 1,
+	BATTLECHIP_INDEX_ID = 2,
+	BATTLECHIP_INDEX_END = 6
+};
+
+enum {
+	BATTLECHIP_OK = 0xFFC6,
+	BATTLECHIP_CONTINUE = 0xFFFF,
+};
+
+static bool GBASIOBattlechipGateLoad(struct GBASIODriver* driver);
+static uint16_t GBASIOBattlechipGateWriteRegister(struct GBASIODriver* driver, uint32_t address, uint16_t value);
+
+static void _battlechipTransfer(struct GBASIOBattlechipGate* gate);
+static void _battlechipTransferEvent(struct mTiming* timing, void* user, uint32_t cyclesLate);
+
+void GBASIOBattlechipGateCreate(struct GBASIOBattlechipGate* gate) {
+	gate->d.init = NULL;
+	gate->d.deinit = NULL;
+	gate->d.load = GBASIOBattlechipGateLoad;
+	gate->d.unload = NULL;
+	gate->d.writeRegister = GBASIOBattlechipGateWriteRegister;
+
+	gate->event.context = gate;
+	gate->event.callback = _battlechipTransferEvent;
+	gate->event.priority = 0x80;
+}
+
+bool GBASIOBattlechipGateLoad(struct GBASIODriver* driver) {
+	struct GBASIOBattlechipGate* gate = (struct GBASIOBattlechipGate*) driver;
+	gate->index = BATTLECHIP_INDEX_END;
+	return true;
+}
+
+uint16_t GBASIOBattlechipGateWriteRegister(struct GBASIODriver* driver, uint32_t address, uint16_t value) {
+	struct GBASIOBattlechipGate* gate = (struct GBASIOBattlechipGate*) driver;
+	switch (address) {
+	case REG_SIOCNT:
+		value &= ~0xC;
+		value |= 0x8;
+		if (value & 0x80) {
+			_battlechipTransfer(gate);
+		}
+		break;
+	case REG_SIOMLT_SEND:
+		break;
+	case REG_RCNT:
+		break;
+	default:
+		break;
+	}
+	return value;
+}
+
+void _battlechipTransfer(struct GBASIOBattlechipGate* gate) {
+	int32_t cycles = GBASIOCyclesPerTransfer[gate->d.p->multiplayerControl.baud][1];
+	mTimingSchedule(&gate->d.p->p->timing, &gate->event, cycles);
+}
+
+void _battlechipTransferEvent(struct mTiming* timing, void* user, uint32_t cyclesLate) {
+	struct GBASIOBattlechipGate* gate = user;
+
+	uint16_t cmd = gate->d.p->p->memory.io[REG_SIOMLT_SEND >> 1];
+	uint16_t reply = 0xFFFF;
+	gate->d.p->p->memory.io[REG_SIOMULTI0 >> 1] = cmd;
+	gate->d.p->p->memory.io[REG_SIOMULTI2 >> 1] = 0xFFFF;
+	gate->d.p->p->memory.io[REG_SIOMULTI3 >> 1] = 0xFFFF;
+	gate->d.p->multiplayerControl.busy = 0;
+	gate->d.p->multiplayerControl.id = 0;
+
+	mLOG(GBA_BATTLECHIP, DEBUG, "> %04x", cmd);
+
+	switch (cmd) {
+	case 0x4000:
+		gate->index = 0;
+	// Fall through
+	case 0:
+		switch (gate->index) {
+		case BATTLECHIP_INDEX_HANDSHAKE_0:
+			reply = 0x00FE;
+			break;
+		case BATTLECHIP_INDEX_HANDSHAKE_1:
+			reply = 0xFFFE;
+			break;
+		case BATTLECHIP_INDEX_ID:
+			reply = gate->chipId;
+			break;
+		default:
+			if (gate->index >= BATTLECHIP_INDEX_END) {
+				reply = BATTLECHIP_OK;
+			} else if (gate->index < 0) {
+				reply = BATTLECHIP_CONTINUE;
+			} else {
+				reply = 0;
+			}
+			break;
+		}
+		++gate->index;
+		break;
+	case 0x8FFF:
+		gate->index = -2;
+	// Fall through
+	default:
+	case 0xA3D0:
+		reply = BATTLECHIP_OK;
+		break;
+	case 0x4234:
+	case 0x574A:
+		reply = BATTLECHIP_CONTINUE;
+		break;
+	}
+
+	mLOG(GBA_BATTLECHIP, DEBUG, "< %04x", reply);
+
+	gate->d.p->p->memory.io[REG_SIOMULTI1 >> 1] = reply;
+
+	if (gate->d.p->multiplayerControl.irq) {
+		GBARaiseIRQ(gate->d.p->p, IRQ_SIO);
+	}
+}