ghidra::BitFieldExpression Class Reference

A container for an expression manipulating a bitfield. More...

#include <expression.hh>

Inheritance diagram for ghidra::BitFieldExpression:

Public Member Functions
const Varnode *	recoverStructurePointer (const Varnode *vn, int4 offset)
	Recover the Varnode holding the pointer to the parent structure.
bool	isValid (void) const
	Is this a valid bitfield expression.

Static Public Member Functions
static const TypeBitField *	getPullField (const PcodeOp *pull)
	Get field description corresponding to given ZPULL or SPULL.

Public Attributes
TypeStruct *	theStruct
	Parent structure containing the bitfield.
const TypeBitField *	bitfield
	Formal bitfield description.
int4	byteRangeOffset
	Offset of byte range into encompassStruct.
int4	offsetToBitStruct
	Offset of structure containing bitfield in encompassStruct.

Protected Member Functions
void	getStructures (Datatype *dt, int4 initByteOff, int4 leastBitOff, bool isBigEndian)
	Recover the structure(s) holding the bitfield.

Detailed Description

A container for an expression manipulating a bitfield.

The expression centers around either a CPUI_INSERT or a CPUI_EXTRACT op but encompasses multiple p-code ops that represent either a single read of or single write to a bitfield within a structure. This class recovers the expected elements of the expression. The method isValid() returns true if the expression has the expected form and can be interpreted as a single read or write.

Member Function Documentation

getPullField()

const TypeBitField * ghidra::BitFieldExpression::getPullField ( const PcodeOp *  pull )

static

Get field description corresponding to given ZPULL or SPULL.

Parameters

pull	is the given ZPULL or SPULL

Returns

the corresponding bitfield description or null

References byteRangeOffset, ghidra::TypeStruct::findMatchingBitField(), ghidra::PcodeOp::getIn(), ghidra::Varnode::getOffset(), ghidra::Varnode::getSize(), ghidra::Varnode::getSpace(), getStructures(), ghidra::Varnode::getTypeReadFacing(), ghidra::AddrSpace::isBigEndian(), offsetToBitStruct, and theStruct.

Referenced by ghidra::RulePullAbsorb::absorbCompZero().

getStructures()

void ghidra::BitFieldExpression::getStructures ( Datatype *  dt, int4  initByteOff, int4  leastBitOff, bool  isBigEndian  )

protected

Recover the structure(s) holding the bitfield.

Find the structure immediately containing the byte range described by the given data-type. Then, given the least significant bit of the bitfield, find the structure immediately containing the bitfield, which may be a different structure.

Parameters

dt	is the data-type describing the byte range
initByteOff	is the initial offset of the byte range within the data-type (may be -1)
leastBitOff	is the least significant bit of the bitfield within the byte range
isBigEndian	is true if the data-type is stored in big endian memory

References ghidra::Datatype::getMetatype(), ghidra::TypePartialStruct::getOffset(), ghidra::TypePartialStruct::getParent(), ghidra::Datatype::getSize(), ghidra::Datatype::getSubType(), ghidra::TYPE_PARTIALSTRUCT, and ghidra::TYPE_STRUCT.

Referenced by getPullField().

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The documentation for this class was generated from the following files:

• expression.hh
• expression.cc