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