Re: [dpdk-dev] [PATCH v2 17/17] libte_acl: remove unused macros.

[Jim Thompson <jim@netgate.com>]

> On Jan 20, 2015, at 4:09 AM, Ananyev, Konstantin <konstantin.ananyev@intel.com> wrote:
> 
> Hi Thomas,
> 
>> -----Original Message-----
>> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
>> Sent: Monday, January 19, 2015 5:18 PM
>> To: Ananyev, Konstantin
>> Cc: dev@dpdk.org
>> Subject: Re: [dpdk-dev] [PATCH v2 17/17] libte_acl: remove unused macros.
>> 
>> 2015-01-12 19:16, Konstantin Ananyev:
>>> /*
>>> + * ACL RT structure is a set of multibit tries (with stride == 8)
>>> + * represented by an array of transitions. The next position is calculated
>>> + * based on the current position and the input byte.
>>> + * Each transition is 64 bit value with the following format:
>>> + * | node_type_specific : 32 | node_type : 3 | node_addr : 29 |
>>> + * For all node types except RTE_ACL_NODE_MATCH, node_addr is an index
>>> + * to the start of the node in the transtions array.
>>> + * Few different node types are used:
>>> + * RTE_ACL_NODE_MATCH:
>>> + * node_addr value is and index into an array that contains the return value
>>> + * and its priority for each category.
>>> + * Upper 32 bits of the transtion value are not used for that node type.
>>> + * RTE_ACL_NODE_QRANGE:
>>> + * that node consist of up to 5 transitions.
>>> + * Upper 32 bits are interpreted as 4 signed character values which
>>> + * are ordered from smallest(INT8_MIN) to largest (INT8_MAX).
>>> + * These values define 5 ranges:
>>> + * INT8_MIN <= range[0]  <= ((int8_t *)&transition)[4]
>>> + * ((int8_t *)&transition)[4] < range[1] <= ((int8_t *)&transition)[5]
>>> + * ((int8_t *)&transition)[5] < range[2] <= ((int8_t *)&transition)[6]
>>> + * ((int8_t *)&transition)[6] < range[3] <= ((int8_t *)&transition)[7]
>>> + * ((int8_t *)&transition)[7] < range[4] <= INT8_MAX
>>> + * So for input byte value within range[i] i-th transition within that node
>>> + * will be used.
>>> + * RTE_ACL_NODE_SINGLE:
>>> + * always transitions to the same node regardless of the input value.
>>> + * RTE_ACL_NODE_DFA:
>>> + * that node consits of up to 256 transitions.
>>> + * In attempt to conserve space all transitions are divided into 4 consecutive
>>> + * groups, by 64 transitions per group:
>>> + * group64[i] contains transitions[i * 64, .. i * 64 + 63].
>>> + * Upper 32 bits are interpreted as 4 unsigned character values one per group,
>>> + * which contain index to the start of the given group within the node.
>>> + * So to calculate transition index within the node for given input byte value:
>>> + * input_byte - ((uint8_t *)&transition)[4 + input_byte / 64].
>>> + */
>> 
>> It's maybe an error. You were only supposed to remove some macros in this patch.
> 
> Ah yes, I added some comments about ACL internal layout.
> Thought it might be useful.
> Forgot to add it into patch description. 
> Are you saying I need to split it into 2 patches, or it is ok like that?

it’s great info, but it should probably go in doc/guides/prog_guide/packet_classif_access_ctrl.rst.

Jim