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//! Enhanced transmit buffer descriptor layout and fields.
use core::sync::atomic::{AtomicU16, AtomicU32, Ordering};
#[repr(C)]
pub struct TxBD {
pub data_length: AtomicU16,
pub flags: AtomicU16,
pub data_buffer_pointer: AtomicU32,
pub errors: AtomicU16,
pub control: AtomicU16,
pub launch_time: AtomicU32,
_reserved0: [u16; 1],
pub last_bdu: AtomicU16,
pub timestamp_1588: AtomicU32,
_reserved1: [u16; 4],
}
pub const FLAGS_READY: u16 = 1 << 15;
pub const FLAGS_WRAP: u16 = 1 << 13;
pub const FLAGS_LAST_IN: u16 = 1 << 11;
pub const FLAGS_TRANSMIT_CRC: u16 = 1 << 10;
impl TxBD {
pub(crate) fn is_ready(&self) -> bool {
self.flags.load(Ordering::SeqCst) & FLAGS_READY != 0
}
}
#[cfg(test)]
mod tests {
use super::TxBD;
use std::ptr::addr_of;
fn zeroed() -> TxBD {
// Safety: zero bitpattern is fine for primitive fields.
unsafe { core::mem::MaybeUninit::zeroed().assume_init() }
}
#[test]
fn field_offsets() {
let txbd = zeroed();
let start = &txbd as *const _ as *const u8;
assert_eq!(unsafe { start.add(0x0) }, addr_of!(txbd.data_length).cast());
assert_eq!(unsafe { start.add(0x2) }, addr_of!(txbd.flags).cast());
assert_eq!(
unsafe { start.add(0x4) },
addr_of!(txbd.data_buffer_pointer).cast()
);
assert_eq!(unsafe { start.add(0x8) }, addr_of!(txbd.errors).cast());
assert_eq!(unsafe { start.add(0xA) }, addr_of!(txbd.control).cast());
assert_eq!(unsafe { start.add(0xC) }, addr_of!(txbd.launch_time).cast());
assert_eq!(unsafe { start.add(0x12) }, addr_of!(txbd.last_bdu).cast());
assert_eq!(
unsafe { start.add(0x14) },
addr_of!(txbd.timestamp_1588).cast()
);
}
}
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