This table is used for data to support transmit VLAN tagging,
VLAN stripping, and VLAN translation. The table is always 4K entries deep but the width
depends on how many of the VLAN functions are included at build time. VLAN translation
requires 12 bits at each location while VLAN stripping and VLAN tagging require 1 bit each
at each location. When all transmit VLAN functions are included, the table is 14 bits wide.
If VLAN functions are not included, the bits for those functions are not present and writes
to those bits have no effect while reads return zero.
Important: The table can be either 1-bit, 2-bits, 12-bits,
13-bits, or 14-bits wide depending on which features are present. The table must be
initialized by software through the AXI4-Lite and is addressed on 32-bit word
boundaries.
The transmit VLAN Table entry with all VLAN
functions present is shown in the first following figure while the second figure shows the
transmit VLAN Table entry with only the translation field. The bit locations for the functions
do not change even when some functions are not used in the build. See Extended VLAN Support for more details.
Figure 1. Transmit VLAN Table Entry with all Fields (0x0000_4000-0x0000_7FFF)
Figure 2. Transmit VLAN Table Entry with One Field (offset 0x0000_4000-0x0000_7FFF)