VICE bridge

vice.js

const vice = Process.getModuleByName('/usr/lib/c64emu.rgl');
const mainloopOuterLoop = vice.getExportByName('maincpu_mainloop').add(0xf4);
const memStore = new NativeFunction(vice.getExportByName('mem_store'), 'void', ['uint16', 'uint8'], { exceptions: 'propagate' });

const ioPending = Memory.alloc(4);
const ioCallbacks = [];

function poke(address, value) {
  schedule(() => { memStore(address, value); });
}

function schedule(callback) {
  ioCallbacks.push(callback);
  ioPending.writeU32(1);
}

const cm = new CModule(`
#include <glib.h>

extern gboolean io_pending;
extern void process_io (void);

void
on_tick (void)
{
  if (io_pending)
    process_io ();
}
`, {
  io_pending: ioPending,
  process_io: new NativeCallback(() => {
    let callback;
    while ((callback = ioCallbacks.shift()) !== undefined) {
      try {
        callback();
      } catch (e) {
        Script.nextTick(() => { throw e; });
      }
    }
    ioPending.writeU32(0);
  }, 'void', []),
});
Interceptor.attach(mainloopOuterLoop, cm.on_tick);