Total rework of simulator for dev branch. Create separate thread for interrupt processes. Tick-accurate simulation of timers. Non-blocking character input for running in realtime mode. Decouple hardware sim from grbl code as much as possible. Expanded command line options. Provisions for cross-platform solution.

sim/platform.h

@@ -0,0 +1,23 @@
+#ifndef platform_h
+
+#ifdef  PLAT_LINUX
+#include "platform_linux.h"
+#else
+#include "platform_windows.h"
+#endif
+
+#define platform_h
+
+void platform_init();
+void platform_terminate();
+
+plat_thread_t* platform_start_thread(plat_threadfunc_t func);
+void platform_stop_thread(plat_thread_t* thread);
+void platform_kill_thread(plat_thread_t* thread);
+
+uint32_t  platform_ns();  //monotonically increasing nanoseconds since program start.
+void platform_sleep(long microsec); //sleep for suggested time in microsec.
+
+uint8_t platform_poll_stdin(); //non-blocking stdin read - returns 0 if no char present, 0xFF for EOF
+
+#endif