ring: Move generic code for ring layout setup to own function

Initialization of the ring->layout members is the same for RX and TX
rings. Instead of duplicating the code in setup_rx_ring_layout() and
setup_tx_ring_layout(), create a new function
setup_ring_layout_generic() which is called from the former two.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

1 files changed, 21 insertions, 0 deletions

diff --git a/ring.c b/ring.c
index e42828e..26de18e 100644
--- a/ring.c
+++ b/ring.c
@@ -1,6 +1,7 @@
 /*
  * netsniff-ng - the packet sniffing beast
  * Copyright 2009, 2010 Daniel Borkmann.
+ * Copyright 2014, 2015 Tobias Klauser
  * Subject to the GPL, version 2.
  */
 
@@ -19,6 +20,26 @@
 #include "ring.h"
 #include "built_in.h"
 
+void setup_ring_layout_generic(int sock, struct ring *ring, size_t size,
+			       bool jumbo_support)
+{
+	fmemset(&ring->layout, 0, sizeof(ring->layout));
+
+	ring->layout.tp_block_size = (jumbo_support ?
+				      RUNTIME_PAGE_SIZE << 4 :
+				      RUNTIME_PAGE_SIZE << 2);
+
+	ring->layout.tp_frame_size = (jumbo_support ?
+				      TPACKET_ALIGNMENT << 12 :
+				      TPACKET_ALIGNMENT << 7);
+
+	ring->layout.tp_block_nr = size / ring->layout.tp_block_size;
+	ring->layout.tp_frame_nr = ring->layout.tp_block_size /
+				   ring->layout.tp_frame_size *
+				   ring->layout.tp_block_nr;
+
+}
+
 void mmap_ring_generic(int sock, struct ring *ring)
 {
 	ring->mm_space = mmap(NULL, ring->mm_len, PROT_READ | PROT_WRITE,