openMSX
DisplayMode.hh
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1 #ifndef DISPLAYMODE_HH
2 #define DISPLAYMODE_HH
3 
4 #include "openmsx.hh"
5 
6 namespace openmsx {
7 
15 {
16 private:
17  explicit DisplayMode(byte mode_) : mode(mode_) {}
22  byte mode;
23 
24 public:
25  enum {
26  GRAPHIC1 = 0x00, // Graphic 1
27  TEXT1 = 0x01, // Text 1
28  MULTICOLOR = 0x02, // Multicolor
29  GRAPHIC2 = 0x04, // Graphic 2
30  TEXT1Q = 0x05, // !!
31  MULTIQ = 0x06, // !!
32  GRAPHIC3 = 0x08, // Graphic 3
33  TEXT2 = 0x09, // Text 2
34  GRAPHIC4 = 0x0C, // Graphic 4
35  GRAPHIC5 = 0x10, // Graphic 5
36  GRAPHIC6 = 0x14, // Graphic 6
37  GRAPHIC7 = 0x1C // Graphic 7
38  };
39 
41  static const byte REG0_MASK = 0x0E;
42 
44  static const byte REG1_MASK = 0x18;
45 
47  static const byte REG25_MASK = 0x18;
48 
50  static const byte YJK = 0x20;
51 
53  static const byte YAE = 0x40;
54 
58  reset();
59  }
60 
67  DisplayMode(byte reg0, byte reg1, byte reg25) {
68  if ((reg25 & 0x08) == 0) reg25 = 0; // If YJK is off, ignore YAE.
69  mode = ((reg25 & 0x18) << 2) // YAE YJK
70  | ((reg0 & 0x0E) << 1) // M5..M3
71  | ((reg1 & 0x08) >> 2) // M2
72  | ((reg1 & 0x10) >> 4); // M1
73  }
74 
75  inline DisplayMode updateReg25(byte reg25) const {
76  if ((reg25 & 0x08) == 0) reg25 = 0; // If YJK is off, ignore YAE.
77  return DisplayMode(getBase() | ((reg25 & 0x18) << 2));
78  }
79 
82  inline void reset() {
83  mode = 0;
84  }
85 
88  inline bool operator==(const DisplayMode& otherMode) const {
89  return mode == otherMode.mode;
90  }
91 
94  inline bool operator!=(const DisplayMode& otherMode) const {
95  return mode != otherMode.mode;
96  }
97 
102  inline byte getByte() const {
103  return mode;
104  }
105 
107  inline void setByte(byte mode_) {
108  mode = mode_;
109  }
110 
116  inline byte getBase() const {
117  return mode & 0x1F;
118  }
119 
123  inline bool isV9938Mode() const {
124  return (mode & 0x18) != 0;
125  }
126 
131  inline bool isTextMode() const {
132  byte base = getBase();
133  return (base == TEXT1) ||
134  (base == TEXT2) ||
135  (base == TEXT1Q);
136  }
137 
142  inline bool isBitmapMode() const {
143  return getBase() >= 0x0C;
144  }
145 
152  inline bool isPlanar() const {
153  // TODO: Is the display mode check OK? Profile undefined modes.
154  return (mode & 0x14) == 0x14;
155  }
156 
159  inline bool isSpriteNarrow() const {
160  // TODO: Check what happens to sprites in Graphic5 + YJK/YAE.
161  return mode == GRAPHIC5;
162  }
163 
170  inline int getSpriteMode(bool isMSX1) const {
171  switch (getBase()) {
172  case GRAPHIC1: case MULTICOLOR: case GRAPHIC2:
173  return 1;
174  case MULTIQ: // depends on VDP type
175  return isMSX1 ? 1 : 0;
176  case GRAPHIC3: case GRAPHIC4: case GRAPHIC5:
177  case GRAPHIC6: case GRAPHIC7:
178  return 2;
179  case TEXT1: case TEXT1Q: case TEXT2:
180  default: // and all other (bogus) modes
181  // Verified on real V9958: none of the bogus modes
182  // show sprites.
183  // TODO check on TMSxxxx
184  return 0;
185  }
186  }
187 
192  inline unsigned getLineWidth() const {
193  // Note: Testing "mode" instead of "base mode" ensures that YJK
194  // modes are treated as 256 pixels wide.
195  return mode == TEXT2 || mode == GRAPHIC5 || mode == GRAPHIC6
196  ? 512
197  : 256;
198  }
199 };
200 
201 } // namespace openmsx
202 
203 #endif
unsigned getLineWidth() const
Get number of pixels on a display line in this mode.
Definition: DisplayMode.hh:192
static const byte REG25_MASK
Bits of VDP register 25 that encode part of the display mode.
Definition: DisplayMode.hh:47
byte getByte() const
Get the dispay mode as a byte: YAE YJK M5..M1 combined.
Definition: DisplayMode.hh:102
static const byte YAE
Encoding of YAE flag.
Definition: DisplayMode.hh:53
bool isV9938Mode() const
Was this mode introduced by the V9938?
Definition: DisplayMode.hh:123
uint8_t byte
8 bit unsigned integer
Definition: openmsx.hh:26
Represents a VDP display mode.
Definition: DisplayMode.hh:14
bool isTextMode() const
Is the current mode a text mode? Text1 and Text2 are text modes.
Definition: DisplayMode.hh:131
int getSpriteMode(bool isMSX1) const
Get the sprite mode of this display mode.
Definition: DisplayMode.hh:170
DisplayMode updateReg25(byte reg25) const
Definition: DisplayMode.hh:75
DisplayMode()
Create the initial display mode.
Definition: DisplayMode.hh:57
static const byte REG1_MASK
Bits of VDP register 1 that encode part of the display mode.
Definition: DisplayMode.hh:44
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:152
DisplayMode(byte reg0, byte reg1, byte reg25)
Create a specific display mode.
Definition: DisplayMode.hh:67
void setByte(byte mode_)
Used for de-serialization.
Definition: DisplayMode.hh:107
static const byte REG0_MASK
Bits of VDP register 0 that encode part of the display mode.
Definition: DisplayMode.hh:41
Thanks to enen for testing this on a real cartridge:
Definition: Autofire.cc:5
bool isSpriteNarrow() const
Are sprite pixels narrow?
Definition: DisplayMode.hh:159
bool operator==(const DisplayMode &otherMode) const
Equals operator.
Definition: DisplayMode.hh:88
static const byte YJK
Encoding of YJK flag.
Definition: DisplayMode.hh:50
bool operator!=(const DisplayMode &otherMode) const
Does-not-equal operator.
Definition: DisplayMode.hh:94
byte getBase() const
Get the base dispay mode as an integer: M5..M1 combined.
Definition: DisplayMode.hh:116
bool isBitmapMode() const
Is the current mode a bitmap mode? Graphic4 and higher are bitmap modes.
Definition: DisplayMode.hh:142
void reset()
Bring the display mode to its initial state.
Definition: DisplayMode.hh:82