summaryrefslogtreecommitdiffstatshomepage
path: root/src/devices/machine/nvram.cpp
blob: 88d1191187aa1c73da4f679a8354329da90e6fcb (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
// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/***************************************************************************

    nvram.c

    Generic non-volatile RAM.

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

#include "emu.h"
#include "machine/nvram.h"

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

// device type definition
const device_type NVRAM = &device_creator<nvram_device>;

//-------------------------------------------------
//  nvram_device - constructor
//-------------------------------------------------

nvram_device::nvram_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
	: device_t(mconfig, NVRAM, "NVRAM", tag, owner, clock, "nvram", __FILE__),
		device_nvram_interface(mconfig, *this),
		m_default_value(DEFAULT_ALL_1),
		m_base(nullptr),
		m_length(0)
{
}


//-------------------------------------------------
//  static_set_interface - configuration helper
//  to set the interface
//-------------------------------------------------

void nvram_device::static_set_default_value(device_t &device, default_value value)
{
	nvram_device &nvram = downcast<nvram_device &>(device);
	nvram.m_default_value = value;
}


//-------------------------------------------------
//  static_set_custom_handler - configuration
//  helper to set a custom callback
//-------------------------------------------------

void nvram_device::static_set_custom_handler(device_t &device, nvram_init_delegate handler)
{
	nvram_device &nvram = downcast<nvram_device &>(device);
	nvram.m_default_value = DEFAULT_CUSTOM;
	nvram.m_custom_handler = handler;
}


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

void nvram_device::device_start()
{
	// bind our handler
	m_custom_handler.bind_relative_to(*owner());
}


//-------------------------------------------------
//  nvram_default - called to initialize NVRAM to
//  its default state
//-------------------------------------------------

void nvram_device::nvram_default()
{
	// make sure we have a valid base pointer
	determine_final_base();

	// region always wins
	if (m_region != nullptr)
	{
		memcpy(m_base, m_region->base(), m_length);
		return;
	}

	// default values for other cases
	switch (m_default_value)
	{
		// all-0's
		case DEFAULT_ALL_0:
			memset(m_base, 0, m_length);
			break;

		// all 1's
		default:
		case DEFAULT_ALL_1:
			memset(m_base, 0xff, m_length);
			break;

		// random values
		case DEFAULT_RANDOM:
		{
			UINT8 *nvram = reinterpret_cast<UINT8 *>(m_base);
			for (int index = 0; index < m_length; index++)
				nvram[index] = machine().rand();
			break;
		}

		// custom handler
		case DEFAULT_CUSTOM:
			m_custom_handler(*this, m_base, m_length);
			break;

		// none - do nothing
		case DEFAULT_NONE:
			break;
	}
}


//-------------------------------------------------
//  nvram_read - called to read NVRAM from the
//  .nv file
//-------------------------------------------------

void nvram_device::nvram_read(emu_file &file)
{
	// make sure we have a valid base pointer
	determine_final_base();

	file.read(m_base, m_length);
}


//-------------------------------------------------
//  nvram_write - called to write NVRAM to the
//  .nv file
//-------------------------------------------------

void nvram_device::nvram_write(emu_file &file)
{
	file.write(m_base, m_length);
}


//-------------------------------------------------
//  determine_final_base - get the final base
//  pointer by looking up the memory share, unless
//  a pointer was provided to us
//-------------------------------------------------

void nvram_device::determine_final_base()
{
	// find our shared pointer with the target RAM
	if (m_base == nullptr)
	{
		memory_share *share = owner()->memshare(tag());
		if (share == nullptr)
			throw emu_fatalerror("NVRAM device '%s' has no corresponding AM_SHARE region", tag());
		m_base = share->ptr();
		m_length = share->bytes();
	}

	// if we are region-backed for the default, find it now and make sure it's the right size
	if (m_region != nullptr && m_region->bytes() != m_length)
		throw emu_fatalerror("%s",string_format("NVRAM device '%s' has a default region, but it should be 0x%I64uX bytes", tag(), m_length).c_str());
}