jos/user/pingpong.c

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2018-10-06 06:52:47 -07:00
// 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;
}
}