SH7670 Datasheet, PDF (513/1292 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7670 Series

Section 13 Ethernet Controller Direct Memory Access Controller (E-DMAC)
13.3.5 Padding Receive Data
The E-DMAC can pad one to three bytes anywhere in the receive data to increase the efficiency of
processing of receive data. For example, by padding two bytes after the 14-byte MAC header of
an Ethernet frame with this function, the subsequent data can be placed at the beginning of the
four-byte boundary.
[No padding]
16-byte
boundary
Receive buffer area
MAC header (14 bytes)
16-byte
boundary
MAC header (14 bytes)
Padding for separation
in the 16-byte boundary
16-byte
boundary
MAC header (14 bytes)
4 bytes
[Padding]
Padding of two bytes after the 14th byte
16-byte
boundary
Receive buffer area
MAC header (14 bytes)
16-byte
boundary
MAC header (14 bytes)
16-byte
boundary
MAC header (14 bytes)
Padding two bytes after
the MAC header
Padding for separation
in the 16-byte boundary
4 bytes
Figure 13.8 Padding Receive Data
Rev. 1.00 Nov. 14, 2007 Page 487 of 1262
REJ09B0437-0100