On 01/22/2011 11:29 AM, Stefan Hajnoczi wrote:
Asynchronous image format code is becoming very complex. Let's try
using coroutines to write sequential code without callbacks but use
coroutines to switch stacks under the hood.
+
+int cc_swap(struct continuation *from, struct continuation *to)
+{
+ to->exited = 0;
+ if (getcontext(&to->last) == -1)
+ return -1;
+ else if (to->exited == 0)
+ to->exited = 1;
+ else if (to->exited == 1)
+ return 1;
+
+ return swapcontext(&from->uc,&to->uc);
+}
swapcontext() is very slow, involving the fpu and a syscall.
A nice trick I've used in the past is to use getcontext/makecontext for
the initial setup and setjmp/longjmp for switching. Of course this can
be done later, as an optimization.
--
error compiling committee.c: too many arguments to function
