BFN::FieldPacking Struct Reference

#include <field_packing.h>

Classes
struct	PackedItem

Public Types
typedef std::vector< PackedItem >::const_iterator	const_iterator
typedef std::vector< PackedItem >::iterator	iterator

Public Member Functions
void	append (const FieldPacking &packing)
	Appends another sequence of packed items to this one.
void	appendField (const IR::Expression *field, cstring source, unsigned width, gress_t gress=INGRESS)
void	appendField (const IR::Expression *field, unsigned width, gress_t gress=INGRESS)
void	appendPadding (unsigned width)
iterator	begin ()
const_iterator	begin () const
void	clear ()
	Removes all packed items from this sequence.
bool	containsFields () const
IR::BFN::ParserState *	createExtractionState (gress_t gress, cstring stateName, const IR::BFN::ParserState *finalState) const
iterator	end ()
const_iterator	end () const
template<Endian Order, typename Func >
void	forEachField (Func func) const
bool	isAlignedTo (unsigned alignment, unsigned phase=0) const
void	padToAlignment (unsigned alignment, unsigned phase=0)

Public Attributes
std::vector< PackedItem >	fields
	The sequence of packed items (fields and padding).
unsigned	totalWidth = 0
	The total width of all packed items in the sequence.

Detailed Description

A field packing format, consisting of a sequence of spans of bits which are either mapped to a field or are treated as padding.

Member Function Documentation

appendField()

void BFN::FieldPacking::appendField	(	const IR::Expression *	field,
		cstring	source,
		unsigned	width,
		gress_t	gress = INGRESS )

Append a field to the sequence of packed items.

Parameters

field	An IR object corresponding to the field. Generally this is an IR::Member of a header or struct, but that's not required.
source	If non-empty, a string identifying the source of the field, for use by the control plane. This is primarily intended for the phase 0 table, since the control plane API we generate uses the names of the action parameter and not the metadata fields we assign those parameters to.
width	The width in bits of the field.
gress	The gress of the field, if it matters.

appendPadding()

void BFN::FieldPacking::appendPadding

(

unsigned

width

)

Appends the specified number of bits of padding to the sequence of packed items.

containsFields()

bool BFN::FieldPacking::containsFields

(

)

const

Returns

true if this sequence contains any fields; if it only contains padding or is totally empty, returns false.

createExtractionState()

IR::BFN::ParserState * BFN::FieldPacking::createExtractionState	(	gress_t	gress,
		cstring	stateName,
		const IR::BFN::ParserState *	finalState ) const

Creates a parser state that extract the fields in this sequence from the input buffer and into the destination specified by each packed item's 'field' member.

Parameters

gress	Which thread these states are intended for.
stateName	The name to use for the generated state.
finalState	The state the generated parser should branch to after its work is complete.

Returns

the root of the resulting parser program.

forEachField()

template<Endian Order, typename Func >

void BFN::FieldPacking::forEachField ( Func func ) const

inline

Iterate over each range of bits in the packing format which is occupied by a field. The callback function should have a prototype like: f(range of bits, field, field source) The ordering of the range of bits is specified by

Template Parameters

Order.

isAlignedTo()

bool BFN::FieldPacking::isAlignedTo	(	unsigned	alignment,
		unsigned	phase = 0 ) const

Returns

true if this sequence's total width is a multiple of the provided alignment (in bits), possibly with an additional bit offset.

See also

padToAlignment.

padToAlignment()

void BFN::FieldPacking::padToAlignment	(	unsigned	alignment,
		unsigned	phase = 0 )

Appends enough padding to make the total width of this sequence a multiple of the provided alignment (in bits).

Parameters

alignment	The desired alignment - e.g., 32 bits.
phase	If provided, an additional offset to the alignment - e.g. a 32 bit alignment with a 2 bit phase would add padding until the total width was 2 bits after a multiple of 32 bits.