summaryrefslogtreecommitdiffstatshomepage
path: root/src/emu/video/ramdac.c
blob: cfa8aab814289f9d1e1f695324cf0576d64fcf81 (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
// license:MAME
// copyright-holders:Angelo Salese
/***************************************************************************

    Generic Palette RAMDAC device

    Written by Angelo Salese

    TODO:
    - masking register, almost likely it controls rollback on incrementing
      r/w palette access;
    - needs information about different models and what exactly they does

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

#include "emu.h"
#include "video/ramdac.h"

// default address map
static ADDRESS_MAP_START( ramdac_palram, AS_0, 8, ramdac_device )
	AM_RANGE(0x000, 0x0ff) AM_RAM // R bank
	AM_RANGE(0x100, 0x1ff) AM_RAM // G bank
	AM_RANGE(0x200, 0x2ff) AM_RAM // B bank
	AM_RANGE(0x300, 0x3ff) AM_NOP
ADDRESS_MAP_END

//**************************************************************************
//  GLOBAL VARIABLES
//**************************************************************************

// device type definition
const device_type RAMDAC = &device_creator<ramdac_device>;


//**************************************************************************
//  LIVE DEVICE
//**************************************************************************

//-------------------------------------------------
//  ramdac_device - constructor
//-------------------------------------------------

ramdac_device::ramdac_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
	: device_t(mconfig, RAMDAC, "RAMDAC", tag, owner, clock, "ramdac", __FILE__),
		device_memory_interface(mconfig, *this),
		m_space_config("videoram", ENDIANNESS_LITTLE, 8, 10, 0, NULL, *ADDRESS_MAP_NAME(ramdac_palram)),
		m_palette(*this),
		m_split_read_reg(0)
{
}

//-------------------------------------------------
//  static_set_palette_tag: Set the tag of the
//  palette device
//-------------------------------------------------

void ramdac_device::static_set_palette_tag(device_t &device, const char *tag)
{
	downcast<ramdac_device &>(device).m_palette.set_tag(tag);
}

//-------------------------------------------------
//  memory_space_config - return a description of
//  any address spaces owned by this device
//-------------------------------------------------

const address_space_config *ramdac_device::memory_space_config(address_spacenum spacenum) const
{
	return (spacenum == AS_0) ? &m_space_config : NULL;
}

//-------------------------------------------------
//  readbyte - read a byte at the given address
//-------------------------------------------------

inline UINT8 ramdac_device::readbyte(offs_t address)
{
	return space().read_byte(address);
}


//-------------------------------------------------
//  writebyte - write a byte at the given address
//-------------------------------------------------

inline void ramdac_device::writebyte(offs_t address, UINT8 data)
{
	space().write_byte(address, data);
}

//-------------------------------------------------
//  device_validity_check - perform validity checks
//  on this device
//-------------------------------------------------

void ramdac_device::device_validity_check(validity_checker &valid) const
{
}

//-------------------------------------------------
//  device_start - device-specific startup
//-------------------------------------------------

void ramdac_device::device_start()
{
	m_palram = auto_alloc_array_clear(machine(), UINT8, 1 << 10);

}


//-------------------------------------------------
//  device_reset - device-specific reset
//-------------------------------------------------

void ramdac_device::device_reset()
{
	m_pal_index[0] = 0;
	m_int_index[0] = 0;
	m_pal_index[1] = 0;
	m_int_index[1] = 0;
	m_pal_mask = 0xff;
}


//**************************************************************************
//  READ/WRITE HANDLERS
//  [0] = W register, [1] = R register
//**************************************************************************

inline void ramdac_device::reg_increment(UINT8 inc_type)
{
	m_int_index[inc_type]++;
	if(m_int_index[inc_type] == 3)
	{
		m_int_index[inc_type] = 0;
		m_pal_index[inc_type]++;
	}
}

READ8_MEMBER( ramdac_device::index_r )
{
	return m_pal_index[0];
}

WRITE8_MEMBER( ramdac_device::index_w )
{
	m_pal_index[0] = data;
	m_int_index[0] = 0;
}

WRITE8_MEMBER( ramdac_device::index_r_w )
{
	m_pal_index[1] = data;
	m_int_index[1] = 0;
}

READ8_MEMBER( ramdac_device::pal_r )
{
	UINT8 res;
	res = readbyte(m_pal_index[m_split_read_reg] | (m_int_index[m_split_read_reg] << 8));
	reg_increment(m_split_read_reg);
	return res;
}

WRITE8_MEMBER( ramdac_device::pal_w )
{
	writebyte(m_pal_index[0] | (m_int_index[0] << 8),data);
	reg_increment(0);
}

WRITE8_MEMBER( ramdac_device::mask_w )
{
	m_pal_mask = data;
}


//**************************************************************************
//  Generic bank read/write handlers
//**************************************************************************

READ8_MEMBER( ramdac_device::ramdac_pal_r )
{
	return m_palram[offset];
}

WRITE8_MEMBER( ramdac_device::ramdac_rgb666_w )
{
	UINT16 pal_offs;

	m_palram[offset] = data & 0x3f;
	pal_offs = (offset & 0xff);

	m_palette->set_pen_color(offset&0xff,pal6bit(m_palram[pal_offs|0x000]),pal6bit(m_palram[pal_offs|0x100]),pal6bit(m_palram[pal_offs|0x200]));
}

WRITE8_MEMBER( ramdac_device::ramdac_rgb888_w )
{
	UINT16 pal_offs;

	m_palram[offset] = data;
	pal_offs = (offset & 0xff);

	m_palette->set_pen_color(offset&0xff,m_palram[pal_offs|0x000],m_palram[pal_offs|0x100],m_palram[pal_offs|0x200]);
}