lan9211 Standard Microsystems Corp., lan9211 Datasheet - Page 33

• Manufacturer Part Number: lan9211
• Description: Lan9211 High-performance Small Form Factor Single-chip Ethernet Controller With Hp Auto-mdix Support
• Manufacturer: Standard Microsystems Corp.

High-Performance Small Form Factor Single-Chip Ethernet Controller with HP Auto-MDIX Support
Datasheet
SMSC LAN9211
3.7.3
3.7.4
Mixed Endian Support
In order to allow flexibility with a range of designs, the LAN9211 supports mixed endian Data FIFO
accesses. The LAN9211 provides the ability to select Data FIFO endianess separately for accesses
through the Data FIFO ports (addresses 00h-3Ch) or using the FIFO_SEL input signal. This is
accomplished via the FPORTEND and FSELEND bits of the
Register, respectively.
The FPORTEND bit determines the endianess of RX and TX Data FIFO host accesses made through
the Data FIFO port addresses (00h-3Ch). When FPORTEND is cleared, Data FIFO port accesses
utilize little endian byte ordering. When FPORTEND is set, Data FIFO port accesses utilize big endian
byte ordering.
The FSELEND bit determines the endianess of RX and TX Data FIFO host accesses when using the
FIFO_SEL signal. When FSELEND is cleared, FIFO_SEL accesses utilize little endian byte ordering.
When FSELEND is set, FIFO_SEL accesses utilize big endian byte ordering.
In addition to mixed endian support, the LAN9211 provides a word swap function, as described in
Section
determines how the Data/Status FIFO’s and CSR host access byte ordering is applied.
describes the various operation modes of the endianess and word swap ordering logic.
illustrates the FIFO access byte ordering under various endianess and word swap settings. Refer to
Section 3.7.4
Note: CSR and status FIFO accesses are not affected by the FPORTEND and FSELEND endianess
Word Swap Function
In addition to mixed endian functionality, the LAN9211 supports a Word Swap Function. This feature
is controlled by the Word Swap Register, which is described in
Swap Control," on page
the Control and Status Registers and the Transmit and Receive Data/Status FIFOs.
Both the word swap function and the mixed endian control bits contain the ability to change the byte
ordering of host data path accesses.
endianess select logic is applied within the LAN9211. Logically, the endian control logic is applied after
the word swap logic for write operations, and before the word swap logic for read operations.
select bits.
3.7.4. The word swap function combined with the endianess select bits described above
for additional details.
96. This register affects how words on the data bus are written to or read from
DATASHEET
Figure 3.2
33
illustrates the order in which the word swap and
Section 5.3.17, "WORD_SWAP—Word
HW_CFG—Hardware Configuration
Revision 2.3 (08-06-08)
Figure 3.3
Table 3.8