#include <mach/thread_switch.h> also included by <mach/mach.h>

mach/thread_switch.h

4 macros

macroSWITCH_OPTION_NONE

#define SWITCH_OPTION_NONE 0

macroSWITCH_OPTION_DEPRESS

#define SWITCH_OPTION_DEPRESS 1

macroSWITCH_OPTION_WAIT

#define SWITCH_OPTION_WAIT 2

macrovalid_switch_option

#define valid_switch_option(opt) (0 <= (opt) && (opt) <= 5)