We allow zero 'values' in a miniflow for it to have the same map
as the corresponding minimask. Minimasks themselves never have
zero data values, though. Document this and optimize the code
accordingly.
Signed-off-by: Jarno Rajahalme <jrajaha...@nicira.com>
---
lib/flow.c | 16 +++-------------
lib/flow.h | 9 +++++++--
lib/match.c | 6 ++----
3 files changed, 12 insertions(+), 19 deletions(-)
diff --git a/lib/flow.c b/lib/flow.c
index 8f80f88..4592023 100644
--- a/lib/flow.c
+++ b/lib/flow.c
@@ -1516,11 +1516,7 @@ miniflow_hash_in_minimask(const struct miniflow *flow,
hash = basis;
for (map = mask->masks.map; map; map = zero_rightmost_1bit(map)) {
- if (*p) {
- int ofs = raw_ctz(map);
- hash = mhash_add(hash, miniflow_get(flow, ofs) & *p);
- }
- p++;
+ hash = mhash_add(hash, miniflow_get(flow, raw_ctz(map)) & *p++);
}
return mhash_finish(hash, (p - mask->masks.values) * 4);
@@ -1542,10 +1538,7 @@ flow_hash_in_minimask(const struct flow *flow, const
struct minimask *mask,
hash = basis;
for (map = mask->masks.map; map; map = zero_rightmost_1bit(map)) {
- if (*p) {
- hash = mhash_add(hash, flow_u32[raw_ctz(map)] & *p);
- }
- p++;
+ hash = mhash_add(hash, flow_u32[raw_ctz(map)] & *p++);
}
return mhash_finish(hash, (p - mask->masks.values) * 4);
@@ -1567,10 +1560,7 @@ flow_hash_in_minimask_range(const struct flow *flow,
uint32_t hash = *basis;
for (; map; map = zero_rightmost_1bit(map)) {
- if (*p) {
- hash = mhash_add(hash, flow_u32[raw_ctz(map)] & *p);
- }
- p++;
+ hash = mhash_add(hash, flow_u32[raw_ctz(map)] & *p++);
}
*basis = hash; /* Allow continuation from the unfinished value. */
diff --git a/lib/flow.h b/lib/flow.h
index a828b66..0b0f593 100644
--- a/lib/flow.h
+++ b/lib/flow.h
@@ -362,7 +362,9 @@ BUILD_ASSERT_DECL(FLOW_U32S <= 64);
*
* Elements in 'values' are allowed to be zero. This is useful for "struct
* minimatch", for which ensuring that the miniflow and minimask members have
- * same 'map' allows optimization .
+ * same 'map' allows optimization. This allowance applies only to a miniflow
+ * that is not a mask. That is, a minimask may NOT have zero elements in
+ * its 'values'.
*/
struct miniflow {
uint64_t map;
@@ -400,7 +402,10 @@ uint64_t miniflow_get_map_in_range(const struct miniflow
*, uint8_t start,
/* A sparse representation of a "struct flow_wildcards".
*
- * See the large comment on struct miniflow for details. */
+ * See the large comment on struct miniflow for details.
+ *
+ * Note: While miniflow can have zero data for a 1-bit in the map,
+ * a minimask may not! We rely on this in the implementation. */
struct minimask {
struct miniflow masks;
};
diff --git a/lib/match.c b/lib/match.c
index 9e5da13..cb72843 100644
--- a/lib/match.c
+++ b/lib/match.c
@@ -1191,10 +1191,8 @@ minimatch_hash_range(const struct minimatch *match,
uint8_t start, uint8_t end,
uint32_t hash = *basis;
for (; map; map = zero_rightmost_1bit(map)) {
- if (*p) {
- hash = mhash_add(hash, *(p - df) & *p);
- }
- p++;
+ hash = mhash_add(hash, *(p - df) & *p);
+ p++;
}
*basis = hash; /* Allow continuation from the unfinished value. */
return mhash_finish(hash, (p - match->mask.masks.values) * 4);
--
1.7.9.5
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