Producer and Consumer – Semaphore Example

program prod_cons_sem;

var in, out: integer;

buf: array[0..n-1] of integer;

empty, full, mutex: semaphore;

procedure append(x: integer); procedure remove(var y: integer);

begin begin

WAIT(full); WAIT(mutex);

WAIT(mutex); WAIT(empty);

buf[in] := x; y := buff[out];

in := (in + 1)mod n; out := (out + 1)mod n;

SIGNAL(mutex); SIGNAL(full);

SIGNAL(empty); SIGNAL(mutex);

end; end;

procedure producer; procedure consumer;

var item: integer; var item: integer;

while true do while true do

begin begin

generate item; remove(item);

append(item); use item;

end; end;

begin {main program executable code}

in := 0; out := 0; full := n; empty := 0, mutex := 1;

cobegin

producer;

consumer;

coend;

end.