#include <decoder.hh>

Inheritance diagram for gem5::ArmISA::Decoder:

Public Member Functions
	Decoder (ISA *isa=nullptr)

void	reset ()
	Reset the decoders internal state. More...

bool	needMoreBytes () const
	Can the decoder accept more data? More...

bool	instReady () const
	Is an instruction ready to be decoded? More...

void	moreBytes (const PCState &pc, Addr fetchPC)
	Feed data to the decoder. More...

StaticInstPtr	decode (ArmISA::PCState &pc)
	Decode an instruction or fetch it from the code cache. More...

void	takeOverFrom (Decoder *old)
	Take over the state from an old decoder when switching CPUs. More...

void	setContext (FPSCR fpscr)

void	setSveLen (uint8_t len)

Public Member Functions inherited from gem5::InstDecoder
template<typename MoreBytesType >
	InstDecoder (MoreBytesType *mb_buf)

virtual StaticInstPtr	fetchRomMicroop (MicroPC micropc, StaticInstPtr curMacroop)

void *	moreBytesPtr () const

size_t	moreBytesSize () const

Addr	pcMask () const

Protected Member Functions
void	process ()
	Pre-decode an instruction from the current state of the decoder. More...

void	consumeBytes (int numBytes)
	Consume bytes by moving the offset into the data word and sanity check the results. More...

StaticInstPtr	decodeInst (ExtMachInst mach_inst)
	Decode a machine instruction without calling the cache. More...

StaticInstPtr	decode (ExtMachInst mach_inst, Addr addr)
	Decode a pre-decoded machine instruction. More...

Protected Attributes
ExtMachInst	emi

uint32_t	data

bool	bigThumb

bool	instDone

bool	outOfBytes

int	offset

bool	foundIt

ITSTATE	itBits

int	fpscrLen

int	fpscrStride

int	sveLen
	SVE vector length, encoded in the same format as the ZCR_EL<x>.LEN bitfields. More...

enums::DecoderFlavor	decoderFlavor

Protected Attributes inherited from gem5::InstDecoder
void *	_moreBytesPtr

size_t	_moreBytesSize

Addr	_pcMask

Static Protected Attributes
static GenericISA::BasicDecodeCache< Decoder, ExtMachInst >	defaultCache
	A cache of decoded instruction objects. More...

Friends
class	GenericISA::BasicDecodeCache< Decoder, ExtMachInst >

Detailed Description

Definition at line 62 of file decoder.hh.

Constructor & Destructor Documentation

◆ Decoder()

gem5::ArmISA::Decoder::Decoder ( ISA * isa = nullptr )

Definition at line 57 of file decoder.cc.

References gem5::ArmISA::ISA::getCurSveVecLenInBitsAtReset(), reset(), and sveLen.

Member Function Documentation

◆ consumeBytes()

void gem5::ArmISA::Decoder::consumeBytes ( int numBytes )

protected

Consume bytes by moving the offset into the data word and sanity check the results.

Definition at line 146 of file decoder.cc.

References data, emi, offset, and outOfBytes.

Referenced by process().

◆ decode() [1/2]

StaticInstPtr gem5::ArmISA::Decoder::decode ( ArmISA::PCState & pc )

Decode an instruction or fetch it from the code cache.

This method decodes the currently pending pre-decoded instruction. Data must be fed to the decoder using moreBytes() until instReady() is true before calling this method.

Parameters

pc	Instruction pointer that we are decoding.

Returns: A pointer to a static instruction or NULL if the decoder isn't ready (see instReady()).

Definition at line 174 of file decoder.cc.

References decode(), emi, foundIt, instDone, itBits, and gem5::MipsISA::pc.

◆ decode() [2/2]

StaticInstPtr gem5::ArmISA::Decoder::decode	(	ExtMachInst	mach_inst,
		Addr	addr
	)

inlineprotected

Decode a pre-decoded machine instruction.

@warn This method takes a pre-decoded instruction as its argument. It should typically not be called directly.

Parameters

mach_inst A pre-decoded instruction

Return values

A	pointer to the corresponding StaticInst object.

Definition at line 126 of file decoder.hh.

References gem5::X86ISA::addr, defaultCache, DPRINTF, and gem5::ArmISA::si.

Referenced by decode().

◆ decodeInst()

StaticInstPtr gem5::ArmISA::Decoder::decodeInst ( ExtMachInst mach_inst )

protected

Decode a machine instruction without calling the cache.

Note: The implementation of this method is generated by the ISA parser script.

@warn This method takes a pre-decoded instruction as its argument. It should typically not be called directly.

Parameters

mach_inst The binary instruction to decode.

Return values

A	pointer to the corresponding StaticInst object.

◆ instReady()

bool gem5::ArmISA::Decoder::instReady ( ) const

inline

Is an instruction ready to be decoded?

CPU models call this method to determine if decode() will return a new instruction on the next call. It typically only returns false if the decoder hasn't received enough data to decode a full instruction.

Definition at line 157 of file decoder.hh.

References instDone.

◆ moreBytes()

void gem5::ArmISA::Decoder::moreBytes	(	const PCState &	pc,
		Addr	fetchPC
	)

Feed data to the decoder.

A CPU model uses this interface to load instruction data into the decoder. Once enough data has been loaded (check with instReady()), a decoded instruction can be retrieved using decode(ArmISA::PCState).

This method is intended to support both fixed-length and variable-length instructions. Instruction data is fetch in MachInst blocks (which correspond to the size of a typical insturction). The method might need to be called multiple times if the instruction spans multiple blocks, in that case needMoreBytes() will return true and instReady() will return false.

The fetchPC parameter is used to indicate where in memory the instruction was fetched from. This is should be the same address as the pc. If fetching multiple blocks, it indicates where subsequent blocks are fetched from (pc + n * sizeof(MachInst)).

Parameters

pc	Instruction pointer that we are decoding.
fetchPC	The address this chunk was fetched from.
inst	Raw instruction data.

Definition at line 155 of file decoder.cc.

References data, emi, fpscrLen, fpscrStride, gem5::letoh(), offset, gem5::ArmISA::OK, outOfBytes, gem5::MipsISA::pc, process(), sveLen, and gem5::ArmISA::UNALIGNED.

◆ needMoreBytes()

bool gem5::ArmISA::Decoder::needMoreBytes ( ) const

inline

Can the decoder accept more data?

A CPU model uses this method to determine if the decoder can accept more data. Note that an instruction can be ready (see instReady() even if this method returns true.

Definition at line 147 of file decoder.hh.

References outOfBytes.

◆ process()

void gem5::ArmISA::Decoder::process ( )

protected

Pre-decode an instruction from the current state of the decoder.

Definition at line 79 of file decoder.cc.

References bigThumb, gem5::bits(), gem5::ArmISA::COND_UC, consumeBytes(), data, DPRINTF, emi, foundIt, instDone, itBits, and offset.

Referenced by moreBytes().

◆ reset()

void gem5::ArmISA::Decoder::reset ( )

Reset the decoders internal state.

Definition at line 68 of file decoder.cc.

References bigThumb, emi, foundIt, instDone, offset, and outOfBytes.

Referenced by Decoder().

◆ setContext()

void gem5::ArmISA::Decoder::setContext ( FPSCR fpscr )

inline

Definition at line 210 of file decoder.hh.

References fpscrLen, and fpscrStride.

◆ setSveLen()

void gem5::ArmISA::Decoder::setSveLen ( uint8_t len )

inline

Definition at line 217 of file decoder.hh.

References gem5::ArmISA::len, and sveLen.

◆ takeOverFrom()

void gem5::ArmISA::Decoder::takeOverFrom ( Decoder * old )

inline

Take over the state from an old decoder when switching CPUs.

Parameters

old	Decoder used in old CPU

Definition at line 205 of file decoder.hh.

Friends And Related Function Documentation

◆ GenericISA::BasicDecodeCache< Decoder, ExtMachInst >

friend class GenericISA::BasicDecodeCache< Decoder, ExtMachInst >

friend

Definition at line 88 of file decoder.hh.

Member Data Documentation

◆ bigThumb

bool gem5::ArmISA::Decoder::bigThumb

protected

Definition at line 68 of file decoder.hh.

Referenced by process(), and reset().

◆ data

uint32_t gem5::ArmISA::Decoder::data

protected

Definition at line 67 of file decoder.hh.

Referenced by consumeBytes(), moreBytes(), and process().

◆ decoderFlavor

enums::DecoderFlavor gem5::ArmISA::Decoder::decoderFlavor

protected

Definition at line 84 of file decoder.hh.

◆ defaultCache

GenericISA::BasicDecodeCache< Decoder, ExtMachInst > gem5::ArmISA::Decoder::defaultCache

staticprotected

A cache of decoded instruction objects.

Definition at line 87 of file decoder.hh.

Referenced by decode().

◆ emi

ExtMachInst gem5::ArmISA::Decoder::emi

protected

Definition at line 66 of file decoder.hh.

Referenced by consumeBytes(), decode(), moreBytes(), process(), and reset().

◆ foundIt

bool gem5::ArmISA::Decoder::foundIt

protected

Definition at line 72 of file decoder.hh.

Referenced by decode(), process(), and reset().

◆ fpscrLen

int gem5::ArmISA::Decoder::fpscrLen

protected

Definition at line 75 of file decoder.hh.

Referenced by moreBytes(), and setContext().

◆ fpscrStride

int gem5::ArmISA::Decoder::fpscrStride

protected

Definition at line 76 of file decoder.hh.

Referenced by moreBytes(), and setContext().

◆ instDone

bool gem5::ArmISA::Decoder::instDone

protected

Definition at line 69 of file decoder.hh.

Referenced by decode(), instReady(), process(), and reset().

◆ itBits

ITSTATE gem5::ArmISA::Decoder::itBits

protected

Definition at line 73 of file decoder.hh.

Referenced by decode(), and process().

◆ offset

int gem5::ArmISA::Decoder::offset

protected

Definition at line 71 of file decoder.hh.

Referenced by consumeBytes(), moreBytes(), process(), and reset().

◆ outOfBytes

bool gem5::ArmISA::Decoder::outOfBytes

protected

Definition at line 70 of file decoder.hh.

Referenced by consumeBytes(), moreBytes(), needMoreBytes(), and reset().

◆ sveLen

int gem5::ArmISA::Decoder::sveLen

protected

SVE vector length, encoded in the same format as the ZCR_EL<x>.LEN bitfields.

Definition at line 82 of file decoder.hh.

Referenced by Decoder(), moreBytes(), and setSveLen().

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

arch/arm/decoder.hh
arch/arm/decoder.cc

Public Member Functions

Protected Member Functions

Protected Attributes

Static Protected Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

◆ Decoder()

Member Function Documentation

◆ consumeBytes()

◆ decode() [1/2]

◆ decode() [2/2]

◆ decodeInst()

◆ instReady()

◆ moreBytes()

◆ needMoreBytes()

◆ process()

◆ reset()

◆ setContext()

◆ setSveLen()

◆ takeOverFrom()

Friends And Related Function Documentation

◆ GenericISA::BasicDecodeCache< Decoder, ExtMachInst >

Member Data Documentation

◆ bigThumb

◆ data

◆ decoderFlavor

◆ defaultCache

◆ emi

◆ foundIt

◆ fpscrLen

◆ fpscrStride

◆ instDone

◆ itBits

◆ offset

◆ outOfBytes

◆ sveLen