summaryrefslogtreecommitdiffstatshomepage
path: root/src/mame/video/z88.cpp
blob: ce89fb011bbec70936245c8e70930b84310c4edd (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
// license:GPL-2.0+
// copyright-holders:Kevin Thacker,Sandro Ronco
/***************************************************************************

  z88.c

  Functions to emulate the video hardware of the Cambridge Z88

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

#include "emu.h"
#include "includes/z88.h"


inline void z88_state::plot_pixel(bitmap_ind16 &bitmap, int x, int y, uint16_t color)
{
	if (x < Z88_SCREEN_WIDTH)
		bitmap.pix16(y, x) = color;
}

// convert absolute offset into correct address to get data from
inline uint8_t* z88_state::convert_address(uint32_t offset)
{
	if (offset < 0x080000) // rom
		return m_bios + (offset & 0x7ffff);
	else if (offset < 0x100000) // slot0
		return m_ram_base + (offset & 0x7ffff);
	else if (offset < 0x200000) // slot1
		return m_carts[1]->get_cart_base() + (offset & 0xfffff);
	else if (offset < 0x300000) // slot2
		return m_carts[2]->get_cart_base() + (offset & 0xfffff);
	else if (offset < 0x400000) // slot3
		return m_carts[3]->get_cart_base() + (offset & 0xfffff);

	return nullptr;
}

/***************************************************************************
  Start the video hardware emulation.
***************************************************************************/

// Initialise the palette
void z88_state::z88_palette(palette_device &palette) const
{
	m_palette->set_pen_color(0, rgb_t(138, 146, 148));
	m_palette->set_pen_color(1, rgb_t(92,  83,  88));
	m_palette->set_pen_color(2, rgb_t(122, 126, 129));
}

/* temp - change to gfxelement structure */

void z88_state::vh_render_8x8(bitmap_ind16 &bitmap, int x, int y, uint16_t pen0, uint16_t pen1, uint8_t *gfx)
{
	for (int h = 0; h < 8; h++)
	{
		uint8_t data = gfx[h];

		for (int b = 0; b < 8; b++)
		{
			plot_pixel(bitmap, x + b, y + h, BIT(data, 7 - b) ? pen1 : pen0);
		}
	}
}

void z88_state::vh_render_6x8(bitmap_ind16 &bitmap, int x, int y, uint16_t pen0, uint16_t pen1, uint8_t *gfx)
{
	for (int h = 0; h < 8; h++)
	{
		uint8_t data = gfx[h] << 2;

		for (int b = 0; b < 6; b++)
		{
			plot_pixel(bitmap, x + 1 + b, y + h, BIT(data, 7 - b) ? pen1 : pen0);
		}
	}
}

void z88_state::vh_render_line(bitmap_ind16 &bitmap, int x, int y, uint16_t pen)
{
	for (int i = 0; i < 8; i++)
	{
		plot_pixel(bitmap, x + i, y + 7, pen);
	}
}

UPD65031_SCREEN_UPDATE(z88_state::lcd_update)
{
	if (sbf == 0)
	{
		// LCD disabled
		bitmap.fill(0);
	}
	else
	{
		uint8_t *vram = convert_address(sbf << 11);

		for (int y = 0; y < (Z88_SCREEN_HEIGHT >> 3); y++)
		{
			int x = 0, c = 0;

			while (x < Z88_SCREEN_WIDTH)
			{
				uint8_t byte0 = vram[(y * 0x100) + c];
				uint8_t byte1 = vram[(y * 0x100) + c + 1];

				// inverted graphics?
				uint16_t pen0 = 0;
				uint16_t pen1 = 0;
				if (byte1 & Z88_SCR_HW_REV)
					pen0 = (byte1 & Z88_SCR_HW_GRY) ? 2 : 1;
				else
					pen1 = (byte1 & Z88_SCR_HW_GRY) ? 2 : 1;

				if ((byte1 & Z88_SCR_HW_NULL) == Z88_SCR_HW_NULL)
				{
					// hidden
				}
				else if (!(byte1 & Z88_SCR_HW_HRS) || (((byte1 & Z88_SCR_HW_CURS) == Z88_SCR_HW_CURS)))
				{
					// low-res 6x8
					const uint16_t ch = (byte0 | (byte1 << 8)) & 0x1ff;

					uint8_t *char_gfx;
					if ((ch & 0x01c0) == 0x01c0)
						char_gfx = convert_address(lores0 << 9) + ((ch & 0x3f) << 3);
					else
						char_gfx = convert_address(lores1 << 12) + (ch << 3);

					// cursor flash
					if (flash && (byte1 & Z88_SCR_HW_CURS) == Z88_SCR_HW_CURS)
						vh_render_6x8(bitmap, x, y << 3, pen1, pen0, char_gfx);
					else
						vh_render_6x8(bitmap, x, y << 3, pen0, pen1, char_gfx);

					// underline?
					if (byte1 & Z88_SCR_HW_UND)
						vh_render_line(bitmap, x, y << 3, pen1);

					x += 6;
				}
				else if ((byte1 & Z88_SCR_HW_HRS) && !(byte1 & Z88_SCR_HW_REV))
				{
					// high-res 8x8
					const uint16_t ch = (byte0 | (byte1 << 8)) & 0x3ff;

					uint8_t *char_gfx;
					if (BIT(ch, 8))
						char_gfx = convert_address(hires1 << 11) + ((ch & 0xff) << 3);
					else
						char_gfx = convert_address(hires0 << 13) + ((ch & 0xff) << 3);

					// flash
					if ((byte1 & Z88_SCR_HW_FLS) && flash)
						pen0 = pen1 = 0;

					vh_render_8x8(bitmap, x, y << 3, pen0, pen1, char_gfx);

					x += 8;
				}

				// every char takes 2 bytes
				c += 2;
			}
		}
	}
}