Struct cranelift_codegen_shared::isa::x86::EncodingBits

pub struct EncodingBits {
    pub opcode_byte: u8,
    pub prefix: OpcodePrefix,
    pub rrr: Integer<u8, Bits3>,
    pub rex_w: Integer<u8, Bits1>,
}

Named interface to the u16 Encoding bits, representing an opcode.

Cranelift requires each recipe to have a single encoding size in bytes. X86 opcodes are variable length, so we use separate recipes for different styles of opcodes and prefixes. The opcode format is indicated by the recipe name prefix.

VEX/XOP and EVEX prefixes are not yet supported. Encodings using any of these prefixes are represented by separate recipes.

The encoding bits are:

0-7: The opcode byte . 8-9: pp, mandatory prefix: 00: none (Op*) 01: 66 (Mp*) 10: F3 (Mp*) 11: F2 (Mp*) 10-11: mm, opcode map: 00: (Op1/Mp1) 01: 0F (Op2/Mp2) 10: 0F 38 (Op3/Mp3) 11: 0F 3A (Op3/Mp3) 12-14 rrr, opcode bits for the ModR/M byte for certain opcodes. 15: REX.W bit (or VEX.W/E)

Fields

opcode_byte: u8

Instruction opcode byte, without the prefix.

prefix: OpcodePrefix

Prefix kind for the instruction, as an enum.

rrr: Integer<u8, Bits3>

Bits for the ModR/M byte for certain opcodes.

rex_w: Integer<u8, Bits1>

REX.W bit (or VEX.W/E).

Methods

impl EncodingBits

pub fn packed_struct_display_formatter<'a>(
    &'a self
) -> PackedStructDisplay<'a, Self, [u8; 2]>

Display formatter for console applications

impl EncodingBits

pub fn new(op_bytes: &[u8], rrr: u16, rex_w: u16) -> Self

Constructs a new EncodingBits from parts.

pub fn bits(self) -> u16

Returns the raw bits.

pub fn pp(self) -> u8

Extracts the PP bits of the OpcodePrefix.

pub fn mm(self) -> u8

Extracts the MM bits of the OpcodePrefix.

Trait Implementations

impl From<u16> for EncodingBits

fn from(bits: u16) -> EncodingBits

Performs the conversion.

impl Clone for EncodingBits

fn clone(&self) -> EncodingBits

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for EncodingBits

impl PartialEq<EncodingBits> for EncodingBits

fn eq(&self, other: &EncodingBits) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &EncodingBits) -> bool

This method tests for !=.

impl Display for EncodingBits

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl StructuralPartialEq for EncodingBits

impl PackedStruct<[u8; 2]> for EncodingBits

Structure that can be packed an unpacked into 2 bytes.

Bit, MSB0	Name	Type
8:15	opcode_byte	u8
4:7	prefix	OpcodePrefix
1:3	rrr	Integer < u8 , packed_bits :: Bits3 >
0	rex_w	Integer < u8 , packed_bits :: Bits1 >

fn pack(&self) -> [u8; 2]

Packs the structure into a byte array.

fn unpack(src: &[u8; 2]) -> Result<EncodingBits, PackingError>

Unpacks the structure from a byte array.

impl PackedStructInfo for EncodingBits

fn packed_bits() -> usize

Number of bits that this structure occupies when being packed.

impl PackedStructSlice for EncodingBits

fn pack_to_slice(&self, output: &mut [u8]) -> Result<(), PackingError>

Pack the structure into an output buffer.

fn unpack_from_slice(src: &[u8]) -> Result<Self, PackingError>

Unpack the structure from a buffer.

fn packed_bytes() -> usize

Number of bytes that this structure demands for packing or unpacking.

fn pack_to_vec(&self) -> Result<Vec<u8>, PackingError>

Pack the structure into a new byte vector.

impl PackedStructDebug for EncodingBits

fn fmt_fields(&self, fmt: &mut Formatter) -> Result<(), Error>

fn packed_struct_display_header() -> &'static str