30 lines
527 B
C
30 lines
527 B
C
// Ping-pong a counter between two processes.
|
|
// Only need to start one of these -- splits into two with fork.
|
|
|
|
#include <inc/lib.h>
|
|
|
|
void
|
|
umain(int argc, char **argv)
|
|
{
|
|
envid_t who;
|
|
|
|
if ((who = fork()) != 0) {
|
|
// get the ball rolling
|
|
cprintf("send 0 from %x to %x\n", sys_getenvid(), who);
|
|
ipc_send(who, 0, 0, 0);
|
|
}
|
|
|
|
while (1) {
|
|
uint32_t i = ipc_recv(&who, 0, 0);
|
|
cprintf("%x got %d from %x\n", sys_getenvid(), i, who);
|
|
if (i == 10)
|
|
return;
|
|
i++;
|
|
ipc_send(who, i, 0, 0);
|
|
if (i == 10)
|
|
return;
|
|
}
|
|
|
|
}
|
|
|