Struct TxDescriptor 

pub struct TxDescriptor { /* private fields */ }

TX DMA descriptor — enhanced 8-word layout (32 bytes).

The ESP32 GMAC requires the enhanced descriptor format when DMABUSMODE.ATDS = 1 (which is what the IDF / ph-esp32-mac driver runs with). Reserved fields below are written by the DMA but unused by the CPU; they exist purely so the descriptor stride is 32 bytes and the DMA does not stomp adjacent descriptors when chained.

Implementations

impl TxDescriptor

pub const SIZE: usize = 32

Descriptor size in bytes (enhanced 8-word layout).

pub const fn new() -> Self

Create a new zeroed TX descriptor.

pub fn setup_chained(&self, buffer: *const u8, next_desc: *const TxDescriptor)

Initialize descriptor for chained mode.

Sets the buffer pointer, next-descriptor pointer, and the SECOND_ADDR_CHAINED flag. The descriptor is left CPU-owned.

pub fn is_owned(&self) -> bool

Check if DMA owns this descriptor.

pub fn set_owned(&self)

Give ownership to DMA.

pub fn clear_owned(&self)

Take ownership from DMA.

pub fn prepare(&self, len: usize, first: bool, last: bool)

Prepare descriptor for transmission with segment flags.

Sets the buffer length and first/last segment flags. Does not set the OWN bit — call set_owned afterwards to submit to DMA.

CIC (Checksum Insertion Control) is always set to 0b11 (bits 23:22), which instructs the MAC to insert the IPv4 header checksum and the TCP/UDP/ICMP payload checksum including the pseudo-header. For non-IPv4 frames the MAC ignores the CIC field, so setting it unconditionally is safe.

pub fn prepare_and_submit(&self, len: usize, first: bool, last: bool)

Prepare and submit to DMA in one operation.

pub fn has_error(&self) -> bool

Check if transmission had errors (error summary bit).

pub fn error_flags(&self) -> u32

Get all error flags from TDES0.

pub fn buffer_addr(&self) -> u32

Get buffer address (TDES2).

pub fn next_desc_addr(&self) -> u32

Get next descriptor address (TDES3, chained mode).

pub fn reset(&self)

Reset descriptor to initial state, preserving the chain pointer.

pub fn raw_tdes0(&self) -> u32

Raw TDES0 value (for debugging / tests).

pub fn raw_tdes1(&self) -> u32

Raw TDES1 value (for debugging / tests).

Trait Implementations

impl Default for TxDescriptor

fn default() -> Self

Returns the “default value” for a type.

impl Send for TxDescriptor

impl Sync for TxDescriptor