From: Ben Pfaff <blp@nicira.com>
Date: Tue, 27 Jan 2009 01:18:25 +0000 (-0800)
Subject: Export network address mask logic in switch-flow.c for public use.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e53f0b3a0323005f28f745469262adf275d9d7a2;p=openvswitch

Export network address mask logic in switch-flow.c for public use.

The flow classifier needs to do the same kinds of tests.
---

diff --git a/lib/flow.h b/lib/flow.h
index 5c6c71d7..367a0d3a 100644
--- a/lib/flow.h
+++ b/lib/flow.h
@@ -33,6 +33,7 @@
 #ifndef FLOW_H
 #define FLOW_H 1
 
+#include <netinet/in.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <string.h>
@@ -89,4 +90,23 @@ flow_hash(const struct flow *flow, uint32_t basis)
                       sizeof *flow / sizeof(uint32_t), basis);
 }
 
+/* Given the wildcard bit count in bits 'shift' through 'shift + 5' (inclusive)
+ * of 'wildcards', returns a 32-bit bit mask with a 1 in each bit that must
+ * match and a 0 in each bit that is wildcarded.
+ *
+ * The bits in 'wildcards' are in the format used in enum ofp_flow_wildcards: 0
+ * is exact match, 1 ignores the LSB, 2 ignores the 2 least-significant bits,
+ * ..., 32 and higher wildcard the entire field.  This is the *opposite* of the
+ * usual convention where e.g. /24 indicates that 8 bits (not 24 bits) are
+ * wildcarded.
+ *
+ * 'wildcards' is in host byte order.  The return value is in network byte
+ * order. */
+static inline uint32_t
+flow_nw_bits_to_mask(uint32_t wildcards, int shift)
+{
+    wildcards = (wildcards >> shift) & 0x3f;
+    return wildcards < 32 ? htonl(~((1u << wildcards) - 1)) : 0;
+}
+
 #endif /* flow.h */
diff --git a/udatapath/switch-flow.c b/udatapath/switch-flow.c
index 6bc2d3c5..79c7eff5 100644
--- a/udatapath/switch-flow.c
+++ b/udatapath/switch-flow.c
@@ -60,12 +60,6 @@ flow_fields_match(const struct flow *a, const struct flow *b, uint16_t w,
             && (w & OFPFW_TP_DST || a->tp_dst == b->tp_dst));
 }
 
-static uint32_t make_nw_mask(int n_wild_bits)
-{
-    n_wild_bits &= (1u << OFPFW_NW_SRC_BITS) - 1;
-    return n_wild_bits < 32 ? htonl(~((1u << n_wild_bits) - 1)) : 0;
-}
-
 /* Returns nonzero if 'a' and 'b' match, that is, if their fields are equal
  * modulo wildcards in 'b', zero otherwise. */
 inline int
@@ -148,8 +142,8 @@ flow_extract_match(struct sw_flow_key* to, const struct ofp_match* from)
     }
 
 	/* We set these late because code above adjusts to->wildcards. */
-	to->nw_src_mask = make_nw_mask(to->wildcards >> OFPFW_NW_SRC_SHIFT);
-	to->nw_dst_mask = make_nw_mask(to->wildcards >> OFPFW_NW_DST_SHIFT);
+	to->nw_src_mask = flow_nw_bits_to_mask(to->wildcards, OFPFW_NW_SRC_SHIFT);
+	to->nw_dst_mask = flow_nw_bits_to_mask(to->wildcards, OFPFW_NW_DST_SHIFT);
 }
 
 /* Allocates and returns a new flow with room for 'actions_len' actions.