Support for Signals

[black-sliver]

Async signalling that rom changed, console was reset or breakpoint was hit would be useful in some scenarios.

The emulator could send support for SIGNALS_LIST (see issue #1), which returns a list of supported signals. The client could then SIGNALS_SUBSCRIBE to signals and the emulator could send signals without breaking existing behaviour.

Signals could be prefixed by '!' (instead of 0x00 for binary and '\n' for ASCII replies).

example:

> EMU_INFO
<
< commands: SIGNALS_LIST,SIGNALS_SUBSCRIBE
<
> SIGNALS_LIST
<
< name: game-changed
< name: emu-reset
<
> SIGNALS_SUBSCRIBE game-changed,emu-reset
< !game-changed
<

[Skarsnik]

This looks good and pretty straightforward. but should a signal be delayed when a command is currently being done?

[black-sliver]

Replying to command has to be atomic currently (i.e. one block), so signal is either sent before or after the reply (so if you wait for a reply and receive '!' it was a signal and not a reply).