Adding upstream version 0.6.0.

Signed-off-by: Daniel Baumann <daniel@debian.org>

doc/ck_ring_dequeue_spmc

@@ -0,0 +1,117 @@
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+.Dd April 20, 2013
+.Dt CK_RING_DEQUEUE_SPMC 3
+.Sh NAME
+.Nm ck_ring_dequeue_spmc
+.Nd dequeue pointer from bounded FIFO
+.Sh LIBRARY
+Concurrency Kit (libck, \-lck)
+.Sh SYNOPSIS
+.In ck_ring.h
+.Ft bool
+.Fn ck_ring_dequeue_spmc "ck_ring_t *ring" "ck_ring_buffer_t *buffer" "void *result"
+.Sh DESCRIPTION
+The
+.Fn ck_ring_dequeue_spmc 3
+function dequeues a pointer from the bounded buffer
+pointed to by
+.Fa ring
+in FIFO fashion. The pointer is stored in the pointer
+pointed to by
+.Fa result .
+The buffer pointed to by
+.Fa buffer
+must be unique to
+.Fa ring .
+The decoupling of the ring from the buffer serves
+to address use-cases involving multiple address spaces
+and DMA, among others.
+If you are on non-POSIX platforms or wish for strict
+compliance with C, then it is recommended to pass a
+pointer of type void ** for
+.Fa result .
+This function is safe to call without locking for UINT_MAX
+concurrent invocations of
+.Fn ck_ring_dequeue_spmc 3
+or
+.Fn ck_ring_trydequeue_spmc 3
+and up to one concurrent
+.Fn ck_ring_enqueue_spmc 3
+or
+.Fn ck_ring_tryenqueue_spmc 3
+invocation. This function provides lock-free progress
+guarantees.
+.Sh EXAMPLE
+.Bd -literal -offset indent
+#include <ck_ring.h>
+
+/* This ring was previously initialized with ck_ring_init. */
+ck_ring_t ring;
+
+/* The ring was initialized for 1023 elements. */
+ck_ring_buffer_t buffer[1024];
+
+void
+dequeue(void)
+{
+	void *result;
+
+	/* Dequeue from ring until it is empty. */
+	while (ck_ring_dequeue_spmc(&ring, &buffer, &result) == true) {
+		/*
+		 * Results contains the oldest pointer in ring
+		 * since the dequeue operation returned true.
+		 */
+		operation(result);
+	}
+
+	/* An empty ring was encountered, leave. */
+	return;
+}
+.Ed
+.Sh RETURN VALUES
+The function returns true if the buffer was non-empty.
+The result of the dequeue operation is stored in the
+value pointed to by
+.Fa result .
+The function will return false if the buffer was empty
+and the value in
+.Fa result
+will be undefined.
+.Sh SEE ALSO
+.Xr ck_ring_init 3 ,
+.Xr ck_ring_trydequeue_spmc 3 ,
+.Xr ck_ring_enqueue_spmc 3 ,
+.Xr ck_ring_enqueue_spmc_size 3 ,
+.Xr ck_ring_dequeue_spsc 3 ,
+.Xr ck_ring_enqueue_spsc 3 ,
+.Xr ck_ring_enqueue_spsc_size 3 ,
+.Xr ck_ring_capacity 3 ,
+.Xr ck_ring_size 3
+.Pp
+Additional information available at http://concurrencykit.org/