factor/vm/os-macosx-x86.h

#define SIGSEGV_EXC_STATE_TYPE i386_exception_state_t
#define SIGSEGV_EXC_STATE_FLAVOR i386_EXCEPTION_STATE
#define SIGSEGV_EXC_STATE_COUNT i386_EXCEPTION_STATE_COUNT
#define SIGSEGV_THREAD_STATE_TYPE i386_thread_state_t
#define SIGSEGV_THREAD_STATE_FLAVOR i386_THREAD_STATE
#define SIGSEGV_THREAD_STATE_COUNT i386_THREAD_STATE_COUNT

#if __DARWIN_UNIX03
    #define SIGSEGV_EXC_STATE_FAULT(exc_state) (exc_state).__faultvaddr
    #define SIGSEGV_STACK_POINTER(thr_state) (thr_state).__esp
    #define SIGSEGV_PROGRAM_COUNTER(thr_state) (thr_state).__eip
#else
    #define SIGSEGV_EXC_STATE_FAULT(exc_state) (exc_state).faultvaddr
    #define SIGSEGV_STACK_POINTER(thr_state) (thr_state).esp
    #define SIGSEGV_PROGRAM_COUNTER(thr_state) (thr_state).eip
#endif

/* Adjust stack pointer so we can push an arg */
INLINE unsigned long fix_stack_ptr(unsigned long sp)
{
	  return sp - (sp & 0xf);
}

INLINE void pass_arg0(SIGSEGV_THREAD_STATE_TYPE *thr_state, CELL arg)
{
	*(CELL *)SIGSEGV_STACK_POINTER(*thr_state) = arg;
	SIGSEGV_STACK_POINTER(*thr_state) -= CELLS;
}