1 files changed, 91 insertions, 0 deletions
diff --git a/src/bd/txbd.rs b/src/bd/txbd.rs
new file mode 100644
index 0000000..9550eff
--- /dev/null
+++ b/src/bd/txbd.rs
@@ -0,0 +1,91 @@
+//! Enhanced transmit buffer descriptor layout and fields.
+
+use ral_registers::RWRegister;
+
+#[repr(C)]
+pub struct TxBD {
+    pub data_length: RWRegister<u16>,
+    pub flags: RWRegister<u16>,
+    pub data_buffer_pointer: RWRegister<u32>,
+    pub errors: RWRegister<u16>,
+    pub control: RWRegister<u16>,
+    pub launch_time: RWRegister<u32>,
+    _reserved0: [u16; 1],
+    pub last_bdu: RWRegister<u16>,
+    pub timestamp_1588: RWRegister<u32>,
+    _reserved1: [u16; 4],
+}
+
+bdfields!(flags, u16,
+    ready           [ offset = 15, bits = 1, ],
+    to1             [ offset = 14, bits = 1, ],
+    wrap            [ offset = 13, bits = 1, ],
+    to2             [ offset = 12, bits = 1, ],
+    last_in         [ offset = 11, bits = 1, ],
+    transmit_crc    [ offset = 10, bits = 1, ],
+);
+
+bdfields!(errors, u16,
+    transmit            [ offset = 15, bits = 1, ],
+    underflow           [ offset = 13, bits = 1, ],
+    excess_collision    [ offset = 12, bits = 1, ],
+    frame_error         [ offset = 11, bits = 1, ],
+    late_collision      [ offset = 10, bits = 1, ],
+    overflow            [ offset =  9, bits = 1, ],
+    timestamp           [ offset =  8, bits = 1, ],
+);
+
+bdfields!(control, u16,
+    interrupt           [ offset = 14, bits = 1, ],
+    timestamp           [ offset = 13, bits = 1, ],
+    pins                [ offset = 12, bits = 1, ],
+    iins                [ offset = 11, bits = 1, ],
+    utlt                [ offset =  8, bits = 1, ],
+    ftype               [ offset =  4, bits = 4, NON_AVB = 0, AVB_A = 1, AVB_B = 2 ],
+);
+
+bdfields!(last_bdu, u16,
+    last_bdu            [ offset = 15, bits = 1, ],
+);
+
+#[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()
+        );
+    }
+
+    #[test]
+    fn bdfields_enum() {
+        let txbd = zeroed();
+        ral_registers::modify_reg!(super, &txbd, control, ftype: AVB_B);
+        assert_eq!(txbd.control.read(), 0x2 << 4);
+        ral_registers::modify_reg!(super, &txbd, control, interrupt: 1);
+        assert_eq!(txbd.control.read(), 0x2 << 4 | 1 << 14);
+        ral_registers::modify_reg!(super, &txbd, control, ftype: 0);
+        assert_eq!(txbd.control.read(), 1 << 14);
+    }
+}