Struct FlitDW0 

pub struct FlitDW0 {
    pub tlp_type: FlitTlpType,
    pub tc: u8,
    pub ohc: u8,
    pub ts: u8,
    pub attr: u8,
    pub length: u16,
}

Parsed representation of a flit-mode DW0 (first 4 bytes of a flit TLP).

Flit-mode DW0 layout:

Byte 0: Type[7:0]            — flat 8-bit type code
Byte 1: TC[2:0] | OHC[4:0]  — traffic class + OHC presence bitmap
Byte 2: TS[2:0] | Attr[2:0] | Length[9:8]
Byte 3: Length[7:0]

Use FlitDW0::from_dw0 to parse from a byte slice.

Fields

tlp_type: FlitTlpType

Decoded TLP type.

tc: u8

Traffic Class (bits [2:0] of byte 1).

ohc: u8

OHC presence bitmap (bits [4:0] of byte 1). Each set bit indicates one Optional Header Content word appended after the base header. Use FlitDW0::ohc_count for the DW count.

ts: u8

Transaction Steering (bits [7:5] of byte 2).

attr: u8

Attributes (bits [4:2] of byte 2).

length: u16

Payload length in DW. A value of 0 encodes 1024 DW.

Implementations

impl FlitDW0

pub fn from_dw0(b: &[u8]) -> Result<Self, TlpError>

Parse the flit-mode DW0 from the first 4 bytes of a byte slice.

Returns Err(TlpError::InvalidLength) if b.len() < 4. Returns Err(TlpError::InvalidType) if the type code is unknown.

pub fn ohc_count(&self) -> u8

Number of OHC extension words present — popcount of FlitDW0::ohc.

pub fn total_bytes(&self) -> usize

Total TLP size in bytes: (base_header_dw + ohc_count) × 4 + payload_bytes

Per PCIe spec a length value of 0 encodes 1024 DW (4096 bytes), but only for types that actually carry a data payload (see FlitTlpType::has_data_payload). Types that never carry payload (read requests, NOP, LocalTlpPrefix, MsgToRc) always contribute zero payload bytes.

impl FlitDW0

pub fn validate_mandatory_ohc(&self) -> Result<(), TlpError>

Validate mandatory OHC rules for this TLP type.

Some flit-mode TLP types require an OHC word to be present:

• IoWrite requires OHC-A2 (bit 0 of the OHC bitmap must be set)
• CfgWrite0 requires OHC-A3 (bit 0 of the OHC bitmap must be set)

Returns Err(TlpError::MissingMandatoryOhc) if the rule is violated.

Trait Implementations

impl Clone for FlitDW0

fn clone(&self) -> FlitDW0

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FlitDW0

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

Formats the value using the given formatter.

impl PartialEq for FlitDW0

fn eq(&self, other: &FlitDW0) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for FlitDW0

impl StructuralPartialEq for FlitDW0