[ovs-dev] [PATCH v3 02/12] flow: Add comments to mf_get_next_in_map().

[Jarno Rajahalme]

> On Oct 17, 2016, at 8:06 PM, Daniele Di Proietto <diproiettod at ovn.org> wrote:
> 
> 2016-10-14 7:37 GMT-07:00 Bhanuprakash Bodireddy <
> bhanuprakash.bodireddy at intel.com <mailto:bhanuprakash.bodireddy at intel.com>>:
> 
>> This patch adds comments to mf_get_next_in_map() to make it more
>> comprehensible.
>> 
>> Signed-off-by: Jarno Rajahalme <jarno at ovn.org <mailto:jarno at ovn.org>>
>> Acked-by: Bhanuprakash Bodireddy <bhanuprakash.bodireddy at intel.com <mailto:bhanuprakash.bodireddy at intel.com>>
>> Acked-by: Antonio Fischetti <antonio.fischetti at intel.com <mailto:antonio.fischetti at intel.com>>
>> 
> 
> The tags here look weird, at least your signoff is missing.
> 

I guess this was based on all the changes in the patch being written by me. I’m OK with these tags, if this makes sense.

  Jarno

> 
>> ---
>> lib/flow.h | 32 +++++++++++++++++++++++++++-----
>> 1 file changed, 27 insertions(+), 5 deletions(-)
>> 
>> diff --git a/lib/flow.h b/lib/flow.h
>> index ea24e28..5a14941 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);
>> 
>>         *fmap -= trash;
>> --
>> 2.4.11
>> 
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>> 
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