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CLK/Components/9918/Implementation/AccessEnums.hpp
2023-05-16 13:01:23 -04:00

116 lines
2.6 KiB
C++

//
// AccessEnums.hpp
// Clock Signal
//
// Created by Thomas Harte on 26/01/2023.
// Copyright © 2023 Thomas Harte. All rights reserved.
//
#ifndef AccessEnums_hpp
#define AccessEnums_hpp
namespace TI::TMS {
// The screen mode is a necessary predecessor to picking the line mode,
// which is the thing latched per line.
enum class ScreenMode {
// Original TMS modes.
Blank,
Text,
MultiColour,
ColouredText,
Graphics,
// 8-bit Sega modes.
SMSMode4,
// New Yamaha V9938 modes.
YamahaText80,
YamahaGraphics3,
YamahaGraphics4,
YamahaGraphics5,
YamahaGraphics6,
YamahaGraphics7,
// Rebranded Yamaha V9938 modes.
YamahaGraphics1 = ColouredText,
YamahaGraphics2 = Graphics,
};
constexpr int pixels_per_byte(ScreenMode mode) {
switch(mode) {
default:
case ScreenMode::Blank: return 1;
case ScreenMode::Text: return 6;
case ScreenMode::MultiColour: return 2;
case ScreenMode::ColouredText: return 8;
case ScreenMode::Graphics: return 8;
case ScreenMode::SMSMode4: return 2;
case ScreenMode::YamahaText80: return 6;
case ScreenMode::YamahaGraphics3: return 8;
case ScreenMode::YamahaGraphics4: return 2;
case ScreenMode::YamahaGraphics5: return 4;
case ScreenMode::YamahaGraphics6: return 2;
case ScreenMode::YamahaGraphics7: return 1;
}
}
constexpr int width(ScreenMode mode) {
switch(mode) {
default:
case ScreenMode::Blank: return 0;
case ScreenMode::Text: return 240;
case ScreenMode::MultiColour: return 256;
case ScreenMode::ColouredText: return 256;
case ScreenMode::Graphics: return 256;
case ScreenMode::SMSMode4: return 256;
case ScreenMode::YamahaText80: return 480;
case ScreenMode::YamahaGraphics3: return 256;
case ScreenMode::YamahaGraphics4: return 256;
case ScreenMode::YamahaGraphics5: return 512;
case ScreenMode::YamahaGraphics6: return 512;
case ScreenMode::YamahaGraphics7: return 256;
}
}
constexpr bool interleaves_banks(ScreenMode mode) {
return mode == ScreenMode::YamahaGraphics6 || mode == ScreenMode::YamahaGraphics7;
}
constexpr bool is_text(ScreenMode mode) {
return mode == ScreenMode::Text || mode == ScreenMode::YamahaText80;
}
enum class FetchMode {
Text,
Character,
Refresh,
SMS,
Yamaha,
};
enum class MemoryAccess {
Read, Write, None
};
enum class VerticalState {
/// Describes any line on which pixels do not appear and no fetching occurs, including
/// the border, blanking and sync.
Blank,
/// A line on which pixels do not appear but fetching occurs.
Prefetch,
/// A line on which pixels appear and fetching occurs.
Pixels,
};
enum class SpriteMode {
Mode1,
Mode2,
MasterSystem,
};
}
#endif /* AccessEnums_hpp */