P4V1::FixExtracts Class Reference

Inheritance diagram for P4V1::FixExtracts:

Public Member Functions
	FixExtracts (ProgramStructure *structure)
const IR::Node *	postorder (IR::MethodCallStatement *statement) override
const IR::Node *	postorder (IR::P4Parser *parser) override
const IR::Node *	postorder (IR::P4Program *program) override

Detailed Description

This pass uses the @length annotation set by the v1 front-end on varbit fields and converts extracts for headers with varbit fields. This only supports headers with a single varbit field. (The @length annotation is inserted as a conversion from the length header property.) For example:

header H { bit<8> len; @length(len) varbit<64> data; } ... H h; pkt.extract(h);

is converted to:

header H { bit<8> len; varbit<64> data; // annotation removed } ... H h;

Fixed-length size of H header H_0 { bit<8> len; }

H_0 h_0; h_0 = pkt.lookahead<H_0>(); pkt.extract(h, h_0.len);