openMSX
DisplayMode.hh
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1#ifndef DISPLAYMODE_HH
2#define DISPLAYMODE_HH
3
4#include "openmsx.hh"
5#include "one_of.hh"
6
7namespace openmsx {
8
16{
17private:
18 constexpr explicit DisplayMode(byte mode_) : mode(mode_) {}
23 byte mode = 0;
24
25public:
26 enum {
27 GRAPHIC1 = 0x00, // Graphic 1
28 TEXT1 = 0x01, // Text 1
29 MULTICOLOR = 0x02, // Multicolor
30 GRAPHIC2 = 0x04, // Graphic 2
31 TEXT1Q = 0x05, // !!
32 MULTIQ = 0x06, // !!
33 GRAPHIC3 = 0x08, // Graphic 3
34 TEXT2 = 0x09, // Text 2
35 GRAPHIC4 = 0x0C, // Graphic 4
36 GRAPHIC5 = 0x10, // Graphic 5
37 GRAPHIC6 = 0x14, // Graphic 6
38 GRAPHIC7 = 0x1C // Graphic 7
39 };
40
42 static constexpr byte REG0_MASK = 0x0E;
43
45 static constexpr byte REG1_MASK = 0x18;
46
48 static constexpr byte REG25_MASK = 0x18;
49
51 static constexpr byte YJK = 0x20;
52
54 static constexpr byte YAE = 0x40;
55
58 constexpr DisplayMode() = default;
59
66 constexpr DisplayMode(byte reg0, byte reg1, byte reg25) {
67 if ((reg25 & 0x08) == 0) reg25 = 0; // If YJK is off, ignore YAE.
68 mode = ((reg25 & 0x18) << 2) // YAE YJK
69 | ((reg0 & 0x0E) << 1) // M5..M3
70 | ((reg1 & 0x08) >> 2) // M2
71 | ((reg1 & 0x10) >> 4); // M1
72 }
73
74 [[nodiscard]] constexpr DisplayMode updateReg25(byte reg25) const {
75 if ((reg25 & 0x08) == 0) reg25 = 0; // If YJK is off, ignore YAE.
76 return DisplayMode(getBase() | ((reg25 & 0x18) << 2));
77 }
78
81 constexpr void reset() {
82 *this = DisplayMode();
83 }
84
87 [[nodiscard]] constexpr bool operator==(const DisplayMode&) const = default;
88
93 [[nodiscard]] constexpr byte getByte() const {
94 return mode;
95 }
96
98 constexpr void setByte(byte mode_) {
99 mode = mode_;
100 }
101
107 [[nodiscard]] constexpr byte getBase() const {
108 return mode & 0x1F;
109 }
110
114 [[nodiscard]] constexpr bool isV9938Mode() const {
115 return (mode & 0x18) != 0;
116 }
117
122 [[nodiscard]] constexpr bool isTextMode() const {
123 return getBase() == one_of(TEXT1, TEXT2, TEXT1Q);
124 }
125
130 [[nodiscard]] constexpr bool isBitmapMode() const {
131 return getBase() >= 0x0C;
132 }
133
140 [[nodiscard]] constexpr bool isPlanar() const {
141 // TODO: Is the display mode check OK? Profile undefined modes.
142 return (mode & 0x14) == 0x14;
143 }
144
147 [[nodiscard]] constexpr bool isSpriteNarrow() const {
148 // TODO: Check what happens to sprites in Graphic5 + YJK/YAE.
149 return mode == GRAPHIC5;
150 }
151
158 [[nodiscard]] constexpr int getSpriteMode(bool isMSX1) const {
159 switch (getBase()) {
160 case GRAPHIC1: case MULTICOLOR: case GRAPHIC2:
161 return 1;
162 case MULTIQ: // depends on VDP type
163 return isMSX1 ? 1 : 0;
164 case GRAPHIC3: case GRAPHIC4: case GRAPHIC5:
165 case GRAPHIC6: case GRAPHIC7:
166 return 2;
167 case TEXT1: case TEXT1Q: case TEXT2:
168 default: // and all other (bogus) modes
169 // Verified on real V9958: none of the bogus modes
170 // show sprites.
171 // TODO check on TMSxxxx
172 return 0;
173 }
174 }
175
180 [[nodiscard]] constexpr unsigned getLineWidth() const {
181 // Note: Testing "mode" instead of "base mode" ensures that YJK
182 // modes are treated as 256 pixels wide.
183 return mode == one_of(TEXT2, GRAPHIC5, GRAPHIC6)
184 ? 512
185 : 256;
186 }
187};
188
189} // namespace openmsx
190
191#endif
Definition: one_of.hh:7
Represents a VDP display mode.
Definition: DisplayMode.hh:16
constexpr bool isSpriteNarrow() const
Are sprite pixels narrow?
Definition: DisplayMode.hh:147
constexpr DisplayMode updateReg25(byte reg25) const
Definition: DisplayMode.hh:74
constexpr byte getBase() const
Get the base display mode as an integer: M5..M1 combined.
Definition: DisplayMode.hh:107
constexpr void setByte(byte mode_)
Used for de-serialization.
Definition: DisplayMode.hh:98
constexpr bool isPlanar() const
Is VRAM "planar" in the current display mode? Graphic 6 and 7 spread their bytes over two VRAM ICs,...
Definition: DisplayMode.hh:140
constexpr unsigned getLineWidth() const
Get number of pixels on a display line in this mode.
Definition: DisplayMode.hh:180
constexpr bool operator==(const DisplayMode &) const =default
Equals operator.
constexpr bool isBitmapMode() const
Is the current mode a bitmap mode? Graphic4 and higher are bitmap modes.
Definition: DisplayMode.hh:130
constexpr DisplayMode()=default
Create the initial display mode.
static constexpr byte REG25_MASK
Bits of VDP register 25 that encode part of the display mode.
Definition: DisplayMode.hh:48
constexpr bool isV9938Mode() const
Was this mode introduced by the V9938?
Definition: DisplayMode.hh:114
static constexpr byte YAE
Encoding of YAE flag.
Definition: DisplayMode.hh:54
constexpr DisplayMode(byte reg0, byte reg1, byte reg25)
Create a specific display mode.
Definition: DisplayMode.hh:66
constexpr void reset()
Bring the display mode to its initial state.
Definition: DisplayMode.hh:81
static constexpr byte REG1_MASK
Bits of VDP register 1 that encode part of the display mode.
Definition: DisplayMode.hh:45
constexpr bool isTextMode() const
Is the current mode a text mode? Text1 and Text2 are text modes.
Definition: DisplayMode.hh:122
static constexpr byte YJK
Encoding of YJK flag.
Definition: DisplayMode.hh:51
constexpr byte getByte() const
Get the display mode as a byte: YAE YJK M5..M1 combined.
Definition: DisplayMode.hh:93
constexpr int getSpriteMode(bool isMSX1) const
Get the sprite mode of this display mode.
Definition: DisplayMode.hh:158
static constexpr byte REG0_MASK
Bits of VDP register 0 that encode part of the display mode.
Definition: DisplayMode.hh:42
This file implemented 3 utility functions:
Definition: Autofire.cc:9