summaryrefslogtreecommitdiffstatshomepage
path: root/src/devices/bus/nes/ggenie.c
blob: f9320a5fbee0d5e5ed5b9c0409dfc8b8b406f87c (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
// license:BSD-3-Clause
// copyright-holders:Fabio Priuli
/***********************************************************************************************************


 NES/Famicom cartridge emulation for Galoob Game Genie PCBs


 Here we emulate the following PCBs

 * Galoob Game Genie, passthrough hacking cart

 ***********************************************************************************************************/


#include "emu.h"
#include "ggenie.h"
#include "includes/nes.h"


#ifdef NES_PCB_DEBUG
#define VERBOSE 1
#else
#define VERBOSE 0
#endif

#define LOG_MMC(x) do { if (VERBOSE) logerror x; } while (0)


//-------------------------------------------------
//  constructor
//-------------------------------------------------

const device_type NES_GGENIE = &device_creator<nes_ggenie_device>;


nes_ggenie_device::nes_ggenie_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
					: nes_nrom_device(mconfig, NES_GGENIE, "NES Cart Game Genie PCB", tag, owner, clock, "nes_ggenie", __FILE__),
						m_ggslot(*this, "gg_slot")
{
}


void nes_ggenie_device::device_start()
{
	common_start();
	save_item(NAME(m_gg_bypass));
}

void nes_ggenie_device::pcb_start(running_machine &machine, UINT8 *ciram_ptr, bool cart_mounted)
{
	device_nes_cart_interface::pcb_start(machine, ciram_ptr, cart_mounted);
	if (m_ggslot->m_cart)
		m_ggslot->pcb_start(m_ciram);
}

void nes_ggenie_device::pcb_reset()
{
	m_chr_source = m_vrom_chunks ? CHRROM : CHRRAM;
	prg32(0);
	chr8(0, m_chr_source);

	set_nt_mirroring(PPU_MIRROR_LOW);
	m_gg_bypass = 0;

	if (m_ggslot->m_cart)
		m_ggslot->m_cart->pcb_reset();
}




/*-------------------------------------------------
 mapper specific handlers
 -------------------------------------------------*/

/*-------------------------------------------------

 Game Genie board emulation

 -------------------------------------------------*/

WRITE8_MEMBER(nes_ggenie_device::write_h)
{
//  LOG_MMC(("axrom write_h, offset: %04x, data: %02x\n", offset, data));
	if (!m_gg_bypass)
	{
		// From blargg: Codes are written to $8001-800C, starting at $800C and going down to $8001.
		// Next, two values are written to $8000. The first specify the kind of codes which have
		// been inserted, the second write to $8000 is always zero (all 8 bits).
		// This probably disables the boot ROM (the code is executing from RAM at this point).
		// Once done, the code jumps to ($FFFC) to begin the game.
		// All 12 bytes from $8001-800C are written regardless of how many codes are inserted.
		// The value written to $8000 is the only clue as to what codes are actually valid and which
		// ones have compare values.
		if (offset)
		{
			int code;
			offset -= 1;
			code = (offset & 0xc) >> 2;
			if (code == 3)
				return; // how did we end up here? the GG is not expected to write to $800d-800f!

			switch (offset & 3)
			{
				case 0:
					m_gg_addr[code] |= (data & 0x7f) << 8;
					break;
				case 1:
					m_gg_addr[code] = data;
					break;
				case 2:
					m_gg_comp[code] = data;
					break;
				case 3:
					m_gg_repl[code] = data;
					break;
			}
			return;
		}

		if (offset == 0 && data == 0)
		{
			m_gg_bypass = 1;
			m_maincpu->set_pc(0xfffc);
		}
		else
		{
			// bit 0 is always set (GG enable?)
			m_gg_is_comp[0] = BIT(data, 1);
			m_gg_is_comp[1] = BIT(data, 2);
			m_gg_is_comp[2] = BIT(data, 3);
			m_gg_disable[0] = BIT(data, 4);
			m_gg_disable[1] = BIT(data, 5);
			m_gg_disable[2] = BIT(data, 6);
			// bit 7 is always clear
			logerror("Game Genie Summary:\n");
			for (int i = 0; i < 3; i++)
			{
				logerror("Code %d: %s\n", i, m_gg_disable[i] ? "No" : "Yes");
				if (!m_gg_disable[i])
				{
					logerror("\tAddr: 0x%X\n", m_gg_addr[i]);
					logerror("\tValue: 0x%X\n", m_gg_repl[i]);
					if (m_gg_is_comp[i])
						logerror("\t if equals: 0x%X\n", m_gg_comp[i]);

				}
			}
		}
	}
	else
		m_ggslot->write_h(space, offset, data, mem_mask);
}

WRITE8_MEMBER(nes_ggenie_device::write_m)
{
	if (m_gg_bypass && m_ggslot)
		m_ggslot->write_m(space, offset, data, mem_mask);
}

WRITE8_MEMBER(nes_ggenie_device::write_l)
{
	if (m_gg_bypass && m_ggslot)
		m_ggslot->write_l(space, offset, data, mem_mask);
}

READ8_MEMBER(nes_ggenie_device::read_h)
{
	if (m_gg_bypass && m_ggslot->m_cart)
	{
		UINT8 rom_value = m_ggslot->m_cart->hi_access_rom(offset);

		// check if GG code has to act on this address
		for (int i = 0; i < 3; i++)
		{
			if (!m_gg_disable[i] && offset == m_gg_addr[i])
			{
				if (!m_gg_is_comp[i] || (m_gg_is_comp[i] && m_gg_comp[i] == rom_value))
					return m_gg_repl[i];
			}
		}

		return  rom_value;
	}
	return hi_access_rom(offset);
}

READ8_MEMBER(nes_ggenie_device::read_m)
{
	if (m_gg_bypass && m_ggslot->m_cart)
		return  m_ggslot->m_cart->read_m(space, offset, mem_mask);

	return 0xff;
}

READ8_MEMBER(nes_ggenie_device::read_l)
{
	if (m_gg_bypass && m_ggslot->m_cart)
		return  m_ggslot->m_cart->read_l(space, offset, mem_mask);

	return 0xff;
}

WRITE8_MEMBER(nes_ggenie_device::chr_w)
{
	int bank = offset >> 10;

	if (m_gg_bypass && m_ggslot->m_cart)
	{
		m_ggslot->m_cart->chr_w(space, offset, data, mem_mask);
		return;
	}

	if (m_chr_src[bank] == CHRRAM)
		m_chr_access[bank][offset & 0x3ff] = data;
}

READ8_MEMBER(nes_ggenie_device::chr_r)
{
	int bank = offset >> 10;

	if (m_gg_bypass && m_ggslot->m_cart)
		return  m_ggslot->m_cart->chr_r(space, offset, mem_mask);

	return m_chr_access[bank][offset & 0x3ff];
}


WRITE8_MEMBER(nes_ggenie_device::nt_w)
{
	int page = ((offset & 0xc00) >> 10);

	if (m_gg_bypass && m_ggslot->m_cart)
	{
		m_ggslot->m_cart->nt_w(space, offset, data, mem_mask);
		return;
	}

	if (!m_nt_writable[page])
		return;

	m_nt_access[page][offset & 0x3ff] = data;
}

READ8_MEMBER(nes_ggenie_device::nt_r)
{
	int page = ((offset & 0xc00) >> 10);

	if (m_gg_bypass && m_ggslot->m_cart)
		return  m_ggslot->m_cart->nt_r(space, offset, mem_mask);

	return m_nt_access[page][offset & 0x3ff];
}

//-------------------------------------------------
//  MACHINE_CONFIG_FRAGMENT( sub_slot )
//-------------------------------------------------

static MACHINE_CONFIG_FRAGMENT( sub_slot )
	MCFG_NES_CARTRIDGE_ADD("gg_slot", nes_cart, NULL)
	MCFG_NES_CARTRIDGE_NOT_MANDATORY
MACHINE_CONFIG_END


//-------------------------------------------------
//  machine_config_additions - device-specific
//  machine configurations
//-------------------------------------------------

machine_config_constructor nes_ggenie_device::device_mconfig_additions() const
{
	return MACHINE_CONFIG_NAME( sub_slot );
}