LAN83C175 Datasheet, PDF (51/92 Pages) SMSC Corporation – Ethernet CARDBUS Integrated Controller With Modem Support

8C - CardBus RECEIVE FRAGMENT LIST
ADDRESS
Reset Value:
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx00
This register contains the current fragment list
address. It is the location in host memory of
the next fragment list entry that the receive
DMA will read. The two lsb’s are fixed at zero
so the address will always be dword aligned.
31 through 2 - Address.
1 and 0 - Not writable - always return zeroes.
90 - CardBus RECEIVE DMA DATA
LENGTH / CONTROL BITS
Reset Value: xxxxxxxxxxxxxxxxxxxx
This register contains the number of bytes
remaining in the current data buffer being filled
by the receive DMA. This register is a down
counter and is decremented by the number of
bytes written each time data is written to the
buffer. The register is also used as a
temporary holding space for the offset into a
frame at which a fragment list based copy
begins. The receive DMA control bits may
also be read and written through this I/O port.
31 through 20 Unused.
19 - OWNER: Indicates whether the last
descriptor read was owned by the NIC (1) or
the host (0). This bit is read only at this
location. It may be written through the
PRSTAT register.
18 - HEADER: Indicates that this descriptor is for
a header copy.
17 - LFFORM: Fragment list format - a 1
indicates that the data length field comes before
the pointer in the fragment list. A 0 indicates that
the pointer comes before the data length.
16 - FRAGLIST: Indicates that this descriptor
points to a fragment list.
15 through 0 - BUFFER LENGTH / OFFSET.
94 - CardBus RECEIVE FRAGMENT COUNT
Reset Value: xxxxxx
This register contains the number of fragments in
the current receive DMA fragment list. It is
decremented just before each fragment is read.
31 through 6 - Unused.
5 through 0 - Fragment Count.
98 - CardBus RECEIVE RAM CURRENT
ADDRESS
Reset Value: xxxxxxxxxxxxxxxxxx
This register contains the byte address of the data
currently being accessed in the local receive RAM.
31 through 18 - Unused.
17 through 0 - RX RAM Address.
51