(MESS) megadriv.c: Added support for Game Genie as a passthru cart. [Fabio Priuli]

.gitattributes

@@ -1025,6 +1025,8 @@ src/emu/bus/macpds/pds_tpdfpd.c svneol=native#text/plain
 src/emu/bus/macpds/pds_tpdfpd.h svneol=native#text/plain
 src/emu/bus/megadrive/eeprom.c svneol=native#text/plain
 src/emu/bus/megadrive/eeprom.h svneol=native#text/plain
+src/emu/bus/megadrive/ggenie.c svneol=native#text/plain
+src/emu/bus/megadrive/ggenie.h svneol=native#text/plain
 src/emu/bus/megadrive/jcart.c svneol=native#text/plain
 src/emu/bus/megadrive/jcart.h svneol=native#text/plain
 src/emu/bus/megadrive/md_carts.c svneol=native#text/plain

hash/megadriv.xml

@@ -31046,22 +31046,24 @@ Notice that these are not working on real hardware due to bugged code with VDP i
 		</part>
 	</software>
 
-	<software name="ggenie" supported="no">
+	<software name="ggenie">
 		<description>Game Genie (Euro, USA, Rev. A)</description>
 		<year>199?</year>
 		<publisher>&lt;unknown&gt;</publisher>
 		<part name="cart" interface="megadriv_cart">
+			<feature name="slot" value="rom_ggenie"/>
 			<dataarea name="rom" width="16" endianness="big" size="32768">
 				<rom name="sgr001-a+sgr002-a.bin" size="32768" crc="14dbce4a" sha1="937e1878ebd104f489e6bdbc410a184f79f1144a" offset="0x000000"/>
 			</dataarea>
 		</part>
 	</software>
 
-	<software name="ggenie1" cloneof="ggenie" supported="no">
+	<software name="ggenie1" cloneof="ggenie">
 		<description>Game Genie (Euro, USA)</description>
 		<year>199?</year>
 		<publisher>&lt;unknown&gt;</publisher>
 		<part name="cart" interface="megadriv_cart">
+			<feature name="slot" value="rom_ggenie"/>
 			<dataarea name="rom" width="16" endianness="big" size="32768">
 				<rom name="sgr001+sgr002.bin" size="32768" crc="5f293e4c" sha1="ea4b0418d90bc47996f6788ad455391d07cad6cc" offset="0x000000"/>
 			</dataarea>

src/emu/bus/bus.mak

@@ -947,6 +947,7 @@ OBJDIRS += $(BUSOBJ)/megadrive
 BUSOBJS += $(BUSOBJ)/megadrive/md_slot.o
 BUSOBJS += $(BUSOBJ)/megadrive/md_carts.o
 BUSOBJS += $(BUSOBJ)/megadrive/eeprom.o
+BUSOBJS += $(BUSOBJ)/megadrive/ggenie.o
 BUSOBJS += $(BUSOBJ)/megadrive/jcart.o
 BUSOBJS += $(BUSOBJ)/megadrive/rom.o
 BUSOBJS += $(BUSOBJ)/megadrive/sk.o

src/emu/bus/megadrive/ggenie.c

@@ -0,0 +1,183 @@
+/***********************************************************************************************************
+
+
+ Game Genie pass-thorugh cart emulation
+
+
+ based on Charles MacDonald's docs: http://cgfm2.emuviews.com/txt/genie.txt
+ 
+
+ There is an interesting difference between Rev.0 and Rev.A
+ After the codes has been entered, the former just performs 
+ a last write to the MODE register (m_gg_regs[0]) which both 
+ sets the enable bits for the 6 available cheats (in the low 
+ 8 bits) and locks the GG so that later reads goes to the 
+ piggyback cart. The latter revision, instead, performs the
+ same operations in two subsequent 8bit writes, accessing 
+ separately the low and high bits of the register.
+ 
+ ***********************************************************************************************************/
+
+#include "emu.h"
+#include "ggenie.h"
+#include "rom.h"
+
+
+//-------------------------------------------------
+//  md_rom_device - constructor
+//-------------------------------------------------
+
+const device_type MD_ROM_GAMEGENIE = &device_creator<md_rom_ggenie_device>;
+
+
+md_rom_ggenie_device::md_rom_ggenie_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
+					: device_t(mconfig, MD_ROM_GAMEGENIE, "MD Game Genie", tag, owner, clock, "md_ggenie", __FILE__),
+						device_md_cart_interface( mconfig, *this ),
+						m_exp(*this, "subslot")
+{
+}
+
+
+void md_rom_ggenie_device::device_start()
+{
+	save_item(NAME(m_gg_bypass));
+	save_item(NAME(m_reg_enable));
+	save_item(NAME(m_gg_regs));
+	save_item(NAME(m_gg_addr));
+	save_item(NAME(m_gg_data));
+}
+
+void md_rom_ggenie_device::device_reset()
+{
+	m_gg_bypass = 0;
+	m_reg_enable = 0;
+	memset(m_gg_regs, 0, sizeof(m_gg_regs));
+	memset(m_gg_addr, 0, sizeof(m_gg_addr));
+	memset(m_gg_data, 0, sizeof(m_gg_data));
+}
+
+/*-------------------------------------------------
+ mapper specific handlers
+ -------------------------------------------------*/
+
+READ16_MEMBER(md_rom_ggenie_device::read)
+{
+	if (!m_gg_bypass || !m_exp->m_cart)
+	{
+		if (m_reg_enable)
+			return m_gg_regs[offset & 0x1f];
+		else
+			return m_rom[MD_ADDR(offset)];
+	}
+
+	if (m_exp->m_cart)
+	{
+		if (offset == m_gg_addr[0]/2 && BIT(m_gg_regs[0], 0))
+			return m_gg_data[0];
+		else if (offset == m_gg_addr[1]/2 && BIT(m_gg_regs[0], 1))
+			return m_gg_data[1];
+		else if (offset == m_gg_addr[2]/2 && BIT(m_gg_regs[0], 2))
+			return m_gg_data[2];
+		else if (offset == m_gg_addr[3]/2 && BIT(m_gg_regs[0], 3))
+			return m_gg_data[3];
+		else if (offset == m_gg_addr[4]/2 && BIT(m_gg_regs[0], 4))
+			return m_gg_data[4];
+		else if (offset == m_gg_addr[5]/2 && BIT(m_gg_regs[0], 5))
+			return m_gg_data[5];
+		else
+			return m_exp->m_cart->read(space, offset);
+	}	
+	else
+		return 0xffff;
+}
+
+WRITE16_MEMBER(md_rom_ggenie_device::write)
+{
+	if (offset >= 0x40/2)
+		return;
+
+	if (ACCESSING_BITS_0_7)
+		m_gg_regs[offset] = (m_gg_regs[offset] & 0xff00) | (data & 0x00ff);
+
+	if (ACCESSING_BITS_8_15)
+		m_gg_regs[offset] = (m_gg_regs[offset] & 0x00ff) | (data & 0xff00);
+
+	//printf("write to 0x%X, data 0x%X\n", offset, data);
+
+	// MODE
+	if (offset == 0)
+	{
+		// bit10 set = read goes to piggyback cart
+		if (data & 0x400)
+			m_gg_bypass = 1;
+		// bit10 unset = read goes to Game Genie ASIC/ROM
+		else
+		{
+			m_gg_bypass = 0;
+			
+			// bit9 set = read goes to ASIC registers
+			if (data & 0x200)
+				m_reg_enable = 1;
+			// bit9 unset = read goes to GG ROM
+			else
+				m_reg_enable = 0;
+		}
+		
+		// LOCK bit
+		if (data & 0x100)
+		{
+			// addresses
+			m_gg_addr[0] = ((m_gg_regs[2]   & 0x3f) << 16) | m_gg_regs[3];
+			m_gg_addr[1] = ((m_gg_regs[5]   & 0x3f) << 16) | m_gg_regs[6];
+			m_gg_addr[2] = ((m_gg_regs[8]   & 0x3f) << 16) | m_gg_regs[9];
+			m_gg_addr[3] = ((m_gg_regs[11]  & 0x3f) << 16) | m_gg_regs[12];
+			m_gg_addr[4] = ((m_gg_regs[14]  & 0x3f) << 16) | m_gg_regs[15];
+			m_gg_addr[5] = ((m_gg_regs[17]  & 0x3f) << 16) | m_gg_regs[18];
+			
+			// data
+			m_gg_data[0] = m_gg_regs[4];
+			m_gg_data[1] = m_gg_regs[7];
+			m_gg_data[2] = m_gg_regs[10];
+			m_gg_data[3] = m_gg_regs[13];
+			m_gg_data[4] = m_gg_regs[16];
+			m_gg_data[5] = m_gg_regs[19];
+
+			//printf("mode %X\n", data);
+			//for (int i = 0; i < 6; i++)
+			//	printf("addr %d = 0x%X - data 0x%X\n", i, m_gg_addr[i], m_gg_data[i]);
+		}
+	}	
+	else if (offset == 1)
+	{
+		// RESET
+		m_gg_regs[1] |= 1;
+	}
+}
+
+//-------------------------------------------------
+//  MACHINE_CONFIG_FRAGMENT( ggenie_slot )
+//-------------------------------------------------
+
+static SLOT_INTERFACE_START(ggenie_sub_cart)
+	SLOT_INTERFACE_INTERNAL("rom",  MD_STD_ROM)
+	SLOT_INTERFACE_INTERNAL("rom_svp",  MD_STD_ROM)
+	SLOT_INTERFACE_INTERNAL("rom_sram",  MD_ROM_SRAM)
+	SLOT_INTERFACE_INTERNAL("rom_sramsafe",  MD_ROM_SRAM)
+	SLOT_INTERFACE_INTERNAL("rom_fram",  MD_ROM_FRAM)
+SLOT_INTERFACE_END
+
+static MACHINE_CONFIG_FRAGMENT( ggenie_slot )
+	MCFG_MD_CARTRIDGE_ADD("subslot", ggenie_sub_cart, NULL)
+	MCFG_MD_CARTRIDGE_NOT_MANDATORY
+MACHINE_CONFIG_END
+
+
+//-------------------------------------------------
+//  machine_config_additions - device-specific
+//  machine configurations
+//-------------------------------------------------
+
+machine_config_constructor md_rom_ggenie_device::device_mconfig_additions() const
+{
+	return MACHINE_CONFIG_NAME( ggenie_slot );
+}

src/emu/bus/megadrive/ggenie.h

@@ -0,0 +1,38 @@
+#ifndef __MD_GGENIE_H
+#define __MD_GGENIE_H
+
+#include "md_slot.h"
+
+
+// ======================> md_rom_ggenie_device
+
+class md_rom_ggenie_device : public device_t,
+						public device_md_cart_interface
+{
+public:
+	// construction/destruction
+	md_rom_ggenie_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock);
+
+	// device-level overrides
+	virtual void device_start();
+	virtual void device_reset();
+	virtual machine_config_constructor device_mconfig_additions() const;
+
+	// reading and writing
+	virtual DECLARE_READ16_MEMBER(read);
+	virtual DECLARE_WRITE16_MEMBER(write);
+
+private:
+	required_device<md_cart_slot_device> m_exp;
+	UINT16 m_gg_regs[0x20];
+	int m_gg_bypass;
+	int m_reg_enable;
+	UINT16 m_gg_addr[6];
+	UINT16 m_gg_data[6];
+};
+
+
+// device type definition
+extern const device_type MD_ROM_GAMEGENIE;
+
+#endif

src/emu/bus/megadrive/md_carts.c

@@ -35,6 +35,8 @@ SLOT_INTERFACE_START(md_cart)
 	SLOT_INTERFACE_INTERNAL("rom_stm95",  MD_EEPROM_STM95)
 // CodeMasters 2-in-1 (reset based)
 	SLOT_INTERFACE_INTERNAL("rom_cm2in1",  MD_ROM_CM2IN1)
+// Game Genie
+	SLOT_INTERFACE_INTERNAL("rom_ggenie",  MD_ROM_GAMEGENIE)
 // unique bankswitch
 	SLOT_INTERFACE_INTERNAL("rom_ssf2",  MD_ROM_SSF2)
 	SLOT_INTERFACE_INTERNAL("rom_radica",  MD_ROM_RADICA)

src/emu/bus/megadrive/md_carts.h

@@ -14,6 +14,7 @@
 #include "rom.h"
 #include "svp.h"
 #include "sk.h"
+#include "ggenie.h"
 #include "eeprom.h"
 #include "jcart.h"
 #include "stm95.h"