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CLK/Components/9918/Implementation/AccessEnums.hpp

86 lines
1.7 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 {
namespace 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;
}
}
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,
};
}
}
#endif /* AccessEnums_hpp */