Data context switching in a semantic processor
Embodiments of a multiple-parsing-context parser and semantic processor are shown and described. The described embodiments allow an input data stream to be parsed in multiple contexts, with the parser switching between contexts as the input data stream dictates. For instance, one embodiment allows a SONET input data stream, including multiple interleaved payloads and SONET transport overhead, to be parsed using multiple grammars, with control passing between the grammars and contexts in a single pass. This approach allows a reconfigurable semantic processor to serve different payload arrangements for a complex multiplexed SONET stream.
1 . An apparatus comprising:
a parser configured to parse a data stream according to a plurality of parsing-contexts, wherein the parser switches parsing-contexts responsive to the semantics of the data stream.
2 . The apparatus according to claim 1 wherein the parser parses a first segment of the data stream according to a first parsing-context and a second segment of the data stream according to a second parsing-context.
3 . The apparatus according to claim 2 wherein the parser includes a data interface configured to receive segments of the data stream and to count a number of received segments, the parser switches parsing-contexts responsive to the counted number.
4 . The apparatus according to claim 1 wherein the parser switches parsing-contexts according to switching symbols identified while parsing the data stream, the switching symbol indicating to the parser a next parsing-context for parsing the data stream.
5 . The apparatus according to claim 4 wherein the parser retrieves the switching symbols from the data stream.
6 . The apparatus according to claim 4 wherein the parser includes a table interface configured to identify production rule codes within a parser table and retrieve production rules from a production rule table according to the identified production rule codes, where at least one of the production rules includes a switching symbol for indicating to the parser the next parsing-context for parsing the data stream.
7 . The apparatus according to claim 1 including
a parser memory configured to store the parsing-contexts; and
a parser state machine configured to control the parsing of the data stream according to the parsing-contexts stored in the parser memory.
8 . The apparatus according to claim 7 wherein the parsing-contexts including one or more parsing symbols that direct the parsing of the data stream, the parser state machine switching parsing-contexts by directing the parser to parse the data stream according to parsing symbols from different parsing-contexts.
9 . The apparatus according to claim 7 wherein the parser memory includes a plurality of parser stacks to store the parsing symbols, the parser stacks dynamically-sized responsive to the parsing of the data stream.
10 . A method comprising:
parsing a data stream according to a plurality of parsing-contexts; and
switching parsing-contexts responsive to the semantics of the data stream.
11 . The method of claim 10 wherein the data stream includes a plurality of segments and parsing each segment according to one of a plurality of parsing contexts.
12 . The method of claim 11
counting a number of the segments within the data stream; and
switching among the parsing-contexts according to the results of the counting.
13 . The method of claim 10 includes
identifying switching symbols during the parsing of the data stream; and
switching parsing contexts responsive to the switching symbols.
14 . The method of claim 13 includes identifying the switching symbols within the data stream.
15 . The method of claim 10 includes
parsing a first segment of the data stream according to a first parsing context;
switching to a second parsing context responsive to the semantics of the data stream; and
parsing a second segment of the data stream according to the second parsing context.
16 . The method of claim 15 includes
switching to a third parsing context responsive to the semantics of the data stream; and
parsing a third segment of the data stream according to the third parsing context.
17 . The method of claim 15 includes
switching to the first parsing context responsive to the semantics of the data stream; and
parsing a third segment of the data stream according to the first parsing context.
18 . The method of claim 10 includes
populating a parser memory with the plurality of parsing-contexts;
parsing the data stream according to one of the parsing-contexts; and
parsing the data stream according to another parsing-context responsive to the semantics of the data stream.
19 . The method of claim 18 wherein the parser memory includes a plurality of parser stacks to store parsing symbols, the parser stacks are dynamically-sized responsive to the parsing of the data stream.
20 . A system comprising:
an input buffer for buffering a data stream configured according to a Synchoronous Optical Network (SONET) protocol; and
a direct execution parser configured to parse the data stream according to a plurality of parsing-contexts.
21 . The system of claim 20 wherein the input buffer is configured to at least partially de-interleave the data stream and the direct execution parser parses the de-interleaved data stream.
22 . The system of claim 21 wherein the data stream including framing data and the input buffer de-interleaves the data stream according to the framing data.
23 . The system of claim 20 wherein the direct execution parser switches parsing-contexts responsive to the SONET protocol.
24 . The system of claim 20 including
a parser table populated with production rule codes;
a production rule table populated with production rules, wherein the direct execution parser is configured to parse the data stream responsive to production rules retrieved from the production rule table.
25 . The system of claim 21 wherein the direct execution parser identifies production rule codes within the parser table and retrieve production rules from the production rule table according to the identified production rule codes.