SH7763 Datasheet, PDF (1039/2026 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC Engine Family SH-4A Series

Section 23 Gigabit Ethernet Controller (GETHER)
23.4.7 Padding Insertion in Receive Data
In the E-DMAC, one to three bytes of padding can be inserted in any byte position of receive data
to improve software handling capability. By using this function, for instance, inserting 2-byte
padding after the MAC header (14 bytes) of Ethernet frame enables data following the MAC
header to set in 4-byte boundary.
[No padding]
16-byte boundary
Receive buffer area
MAC header (14 bytes)
16-byte boundary
MAC header (14 bytes)
Padding for separation
at 16 byte boundary
16-byte boundary
MAC header (14 bytes)
[No padding]
4 bytes
Insert 2-byte padding after 14th byte
16-byte boundary
Receive buffer area
MAC header (14 bytes)
16-byte boundary
16-byte boundary
MAC header (14 bytes)
MAC header (14 bytes)
2 bytes padding inserted
after MAC header
Padding for separation
at 16-bytes boundary
4 bytes
Figure 23.14 Padding Insertion in Receive Data
Rev. 1.00 Oct. 01, 2007 Page 973 of 1956
REJ09B0256-0100