zxq5
adfba876d2
- setup new UI layout using tiling and an action/message based system for updating global state based on interactions with individual tiles and vice versa - added custom dialogs and UI helpers to create a more cohesive UI - added a disassembler widget (WIP) - added a documentation widget (WIP) - refactored backend halt/pause logic to fix bugs. - started emulator implementation documentation (to complement the ISA spec)
80 lines
2.2 KiB
Markdown
80 lines
2.2 KiB
Markdown
# States
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### Definitions
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- Model
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- Private - internal state of the processor, always up to date.
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- time: Duration,
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- state: **Running | Paused | Halted | Shutdown | Breakpoint**
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- Shared - shared across threads. updated periodically
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- time: Duration
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- cycles: Integer
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## Running
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the running state is the main loop of the emulator.
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### Responsibilities:
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- run fetch-decode-execute cycle
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- handle interrupts
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- go to paused state if requested by UI.
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- go to the halted state if it hits that instruction
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- keep the UI updated occasionally, but prioritise extremely high throughput
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### Transitions:
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- to `Paused`
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- when the `pause` signal is received
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- to `Halted`
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- when hitting the `Hlt` instruction.
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- to `Shutdown`
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- when the `shutdown` signal is received
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***DEBUG IMPLEMENTATION ONLY***
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- to `Breakpoint`
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- when hitting a breakpoint
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## Paused
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the paused state is started and ended by the UI thread.
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### Responsibilities:
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- update the UI when requested
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- reset when requested by the UI
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- save the running-time and executed instructions since the last pause state.
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- add `private.time` to `shared.time`
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- reset `private.time, shared.time, shared.cycles` on state exit
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### Transitions
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- to `Halted`
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- when the `run` signal is received and the previous state was `Halted`
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- to `Running`
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- when the `run` signal is received
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- to `Shutdown`
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- when the `shutdown` signal is received
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## Halted
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the state reached when the emulator has hit a `Hlt` instruction and is waiting to continue
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### Responsibilities:
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- update the UI when requested
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- unpause when an interrupt is received
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- keep track of the time spent in the running state across multiple hlt/interrupt cycles
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- add `private.time` to `shared.time`
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- reset `private.time` on state exit
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- preserve `shared` on state exit
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### Transitions
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- to `Running`
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- when the `interrupt` signal is received
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- to `Paused`
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- when the `pause` signal is received
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- to `Shutdown`
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- when the `shutdown` signal is received
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## Shutdown
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the shutdown state is a terminal state. the emulator cleans up its memory and exits.
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## Breakpoint
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debug state used only in the debugger implementation of the emulator
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### Transitions
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- to `Running`
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- when the `run` signal is received |