mamelink readme

mamelink/README.md

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+# mamelink
+A compatibility shim for Lucasfilm Games' "fastlink", using a MAME plugin to implement similar functionality.
+
+## Building
+Run `make`. Assumes a POSIX-like environment. Works On My Machine, totally untested on anything besides Linux.
+
+## Booting reno
+Run `./start`. Assumes that `mame` is in the current path, with C64 ROMs installed.
+
+## How It Works
+It's a terrible, awful, very bad, no good hack, but it does the trick and should hopefully be portable, even to an enscripten-type browser environment. To send a command to the `mamelink` plugin, the `mamelink.c` library creates a file called `mameplugins/mamelink/linkin` with
+the request. The plugin checks for the existence of this file constantly. Once it is able to open it, it executes the instructions it finds, creates a file called `mameplugins/mamelink/linkout` with any response, and deletes `mameplugins/mamelink/linkin`. The `mamelink.c` library waits for the `linkin` file to be deleted, reads all of the data out of `linkout`, if any, and deletes it.
+
+Some amount of energy was put into avoiding race conditions but not a lot. Try not to have multiple programs poking at C64 memory at the same time. This seems unlikely to happen in practice, at least.
+
+## Why did you do it like that
+Because every sensible, normal way of doing it was broken thanks to Lua's underpowered standard library, MAME's requirement for non-blocking I/O, and the weird not-quite-acceptable socket support that MAME provides in its plugin interface. (You can only accept a connection from a single client at a time, and there is no way to determine if a client has disconnected.)