1 #include "threadimpl.h"
2 
3 void
4 makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
5 {
6 	int n;
7 	int *sp;
8 
9 	sp = (int*)ucp->uc_stack.ss_sp+ucp->uc_stack.ss_size/4;
10 	sp -= argc;
11 	/*
12 	 * Stack pointer at call instruction (before return address
13 	 * gets pushed) must be 16-byte aligned.
14 	 */
15 	if((uintptr)sp%4)
16 		abort();
17 	while((uintptr)sp%16)
18 		sp--;
19 	memmove(sp, &argc+1, argc*sizeof(int));
20 	*--sp = 0;		/* return address */
21 	ucp->uc_mcontext.mc_eip = (long)func;
22 	ucp->uc_mcontext.mc_esp = (int)sp;
23 }
24 
25 int
26 swapcontext(ucontext_t *oucp, ucontext_t *ucp)
27 {
28 	if(getcontext(oucp) == 0)
29 		setcontext(ucp);
30 	return 0;
31 }
32