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@@ -1,12 +1,28 @@
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main:
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while true:
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case read_char() of:
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'R': create_thread(reader)
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'W': create_thread(writer)
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EOF: return
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reader:
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read()
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writer:
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write()
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shared readers := 0
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shared readers_mutex := semaphore(1)
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shared can_access := semaphore(1)
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+
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main:
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while true:
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case read_char() of:
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'R': create_thread(reader)
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'W': create_thread(writer)
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EOF: return
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+
// WRRW
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+
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reader:
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wait(readers_mutex)
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if ++readers = 1 then
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wait(can_access)
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signal(readers_mutex)
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read()
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wait(readers_mutex)
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if --readers = 0 then
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signal(can_access);
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signal(readers_mutex)
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writer:
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wait(can_access)
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write()
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signal(can_access)
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