Functions provided by the replayer debugger

// Step back in the currently replayed trace
// Returns: error code (0 if none happened).

success step_back();

// Set the current event number, changing the PC register.
// Input  : the event to move to
// Events are numbered in reverse order, i.e. 0 is the last available event.
// Returns: error code.

success set_current_tev(long event);

// Get the current event number.
// Returns: the current event number.

long get_current_tev();