#include <decoder.hh>

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, MachInst inst)
	Feed data to the decoder. More...

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

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

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

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...

Protected Attributes
ExtMachInst	emi

MachInst	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::DecoderFlavour	decoderFlavour

Static Protected Attributes
static GenericISA::BasicDecodeCache	defaultCache
	A cache of decoded instruction objects. More...

Detailed Description

Definition at line 59 of file decoder.hh.

Constructor & Destructor Documentation

◆ Decoder()

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

Definition at line 57 of file decoder.cc.

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

Member Function Documentation

◆ consumeBytes()

void 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 emi, offset, and outOfBytes.

Referenced by process().

◆ decode() [1/2]

StaticInstPtr 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 emi, foundIt, instDone, and itBits.

Referenced by instReady().

◆ decode() [2/2]

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

inline

Decode a pre-decoded machine instruction.

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 173 of file decoder.hh.

References GenericISA::BasicDecodeCache::decode(), and decodeInst().

◆ decodeInst()

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

Decode a machine instruction without calling the cache.

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

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.

Referenced by decode().

◆ instReady()

bool 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 121 of file decoder.hh.

References decode(), instDone, moreBytes(), and MipsISA::pc.

◆ moreBytes()

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

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, letoh(), offset, ArmISA::OK, outOfBytes, process(), sveLen, and ArmISA::UNALIGNED.

Referenced by instReady().

◆ needMoreBytes()

bool 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 111 of file decoder.hh.

References outOfBytes.

◆ process()

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

Referenced by moreBytes().

◆ reset()

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

inline

Definition at line 201 of file decoder.hh.

◆ setSveLen()

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

inline

Definition at line 207 of file decoder.hh.

References ArmISA::len.

◆ takeOverFrom()

void 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 197 of file decoder.hh.

Member Data Documentation

◆ bigThumb

bool ArmISA::Decoder::bigThumb

protected

Definition at line 65 of file decoder.hh.

Referenced by process(), and reset().

◆ data

MachInst ArmISA::Decoder::data

protected

Definition at line 64 of file decoder.hh.

Referenced by moreBytes(), and process().

◆ decoderFlavour

Enums::DecoderFlavour ArmISA::Decoder::decoderFlavour

protected

Definition at line 81 of file decoder.hh.

◆ defaultCache

GenericISA::BasicDecodeCache ArmISA::Decoder::defaultCache

staticprotected

A cache of decoded instruction objects.

Definition at line 84 of file decoder.hh.

◆ emi

ExtMachInst ArmISA::Decoder::emi

protected

Definition at line 63 of file decoder.hh.

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

◆ foundIt

bool ArmISA::Decoder::foundIt

protected

Definition at line 69 of file decoder.hh.

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

◆ fpscrLen

int ArmISA::Decoder::fpscrLen

protected

Definition at line 72 of file decoder.hh.

Referenced by moreBytes().

◆ fpscrStride

int ArmISA::Decoder::fpscrStride

protected

Definition at line 73 of file decoder.hh.

Referenced by moreBytes().

◆ instDone

bool ArmISA::Decoder::instDone

protected

Definition at line 66 of file decoder.hh.

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

◆ itBits

ITSTATE ArmISA::Decoder::itBits

protected

Definition at line 70 of file decoder.hh.

Referenced by decode(), and process().

◆ offset

int ArmISA::Decoder::offset

protected

Definition at line 68 of file decoder.hh.

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

◆ outOfBytes

bool ArmISA::Decoder::outOfBytes

protected

Definition at line 67 of file decoder.hh.

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

◆ sveLen

int ArmISA::Decoder::sveLen

protected

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

Definition at line 79 of file decoder.hh.

Referenced by Decoder(), and moreBytes().

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

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()

Member Data Documentation

◆ bigThumb

◆ data

◆ decoderFlavour

◆ defaultCache

◆ emi

◆ foundIt

◆ fpscrLen

◆ fpscrStride

◆ instDone

◆ itBits

◆ offset

◆ outOfBytes

◆ sveLen