This patch adds comments to mf_get_next_in_map() to make it more
comprehensible.
Signed-off-by: Bhanuprakash Bodireddy <bhanuprakash.bodire...@intel.com>
Signed-off-by: Jarno Rajahalme <ja...@ovn.org>
Acked-by: Antonio Fischetti <antonio.fische...@intel.com>
---
lib/flow.h | 32 +++++++++++++++++++++++++++-----
1 file changed, 27 insertions(+), 5 deletions(-)
diff --git a/lib/flow.h b/lib/flow.h
index 15b50b1..175373c 100644
--- a/lib/flow.h
+++ b/lib/flow.h
@@ -564,12 +564,27 @@ flow_values_get_next_in_maps(struct
flow_for_each_in_maps_aux *aux,
flow_values_get_next_in_maps(&aux__, &(VALUE));)
struct mf_for_each_in_map_aux {
- size_t unit;
- struct flowmap fmap;
- struct flowmap map;
- const uint64_t *values;
+ size_t unit; /* Current 64-bit unit of the flowmaps
+ being processed. */
+ struct flowmap fmap; /* Remaining 1-bits corresponding to the
+ 64-bit words in ‘values’ */
+ struct flowmap map; /* Remaining 1-bits corresponding to the
+ 64-bit words of interest. */
+ const uint64_t *values; /* 64-bit words corresponding to the
+ 1-bits in ‘fmap’. */
};
+/* Get the data from ‘aux->values’ corresponding to the next lowest 1-bit
+ * in ‘aux->map’, given that ‘aux->values’ points to an array of 64-bit
+ * words corresponding to the 1-bits in ‘aux->fmap’, starting from the
+ * rightmost 1-bit.
+ *
+ * Returns ’true’ if the traversal is incomplete, ‘false’ otherwise.
+ * ‘aux’ is prepared for the next iteration after each call.
+ *
+ * This is used to traverse through, for example, the values in a miniflow
+ * representation of a flow key selected by non-zero 64-bit words in a
+ * corresponding subtable mask. */
static inline bool
mf_get_next_in_map(struct mf_for_each_in_map_aux *aux,
uint64_t *value)
@@ -577,8 +592,10 @@ mf_get_next_in_map(struct mf_for_each_in_map_aux *aux,
map_t *map, *fmap;
map_t rm1bit;
+ /* Skip empty map units. */
while (OVS_UNLIKELY(!*(map = &aux->map.bits[aux->unit]))) {
- /* Skip remaining data in the previous unit. */
+ /* Skip remaining data in the current unit before advancing
+ * to the next. */
aux->values += count_1bits(aux->fmap.bits[aux->unit]);
if (++aux->unit == FLOWMAP_UNITS) {
return false;
@@ -589,7 +606,12 @@ mf_get_next_in_map(struct mf_for_each_in_map_aux *aux,
*map -= rm1bit;
fmap = &aux->fmap.bits[aux->unit];
+ /* If the rightmost 1-bit found from the current unit in ‘aux->map’
+ * (‘rm1bit’) is also present in ‘aux->fmap’, store the corresponding
+ * value from ‘aux->values’ to ‘*value', otherwise store 0. */
if (OVS_LIKELY(*fmap & rm1bit)) {
+ /* Skip all 64-bit words in ‘values’ preceding the one corresponding
+ * to ‘rm1bit’. */
map_t trash = *fmap & (rm1bit - 1);
/* Avoid resetting 'fmap' and calling count_1bits() when trash is
--
2.4.11
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