20.6.6.2 Bit 1 - W - Wrap
o - This is not the last data buffer descriptor in the buffer descriptor table.
1 - This is the last data buffer descriptor
in
the buffer descriptor table. After this buffer has been used,
MAL will transfer data to the first buffer descriptor in the
table.
This bit is controlled by software only. It controls
MAL
activities and does not affect the
COMMAC
channel.
20.6.6.3 Bit 2 -
CM
- Continuous Mode
o - Normal Operation
1 - Continuous Operation. After this buffer descriptor is
closed, the E-bit is not cleared by
MAl.
This
ensures that the data buffer is ready to receive data when
MAL
next accesses its buffer descriptor.
However, the E-bit is
cleared if an error occurs during reception.
This bit is
controlled by software only. It controls
MAL
activities and does not affect the
COMMAC
channel.
20.6.6.4 Bit 3 - L - Last
0-
This is not the last buffer in the current packet.
1 - This is the
last buffer in the current packet.
This bit is updated by
MAL
following the activity of the channel.
20.6.6.5 Bit 4 - F - First
0-
This is not the first buffer in the current packet.
1 - This is the first buffer in the current packet.
This bit is updated by
MAL
following the activity of the channel.
20.6.6.6 Bit 5 - I - Interrupt
1 - After finish processing the current buffer, if this bit is 1, the end of buffer field in the End of Buffer
Interrupt Status Register is set and the end
of
buffer interrupt is asserted.
o - No action is taken by
MAL
at the end of the current buffer.
MAL asserts the end of buffer interrupt after updating the buffer descriptor's status
field.
This bit is controlled by software only. It controls MAL activities and does not affect the COMMAC.
20.6.6.7 Bits 6 to 15
These bits are COM MAC-specific and they may contain control fields generated by the software in
order to
control the COM MAC channel. They may also contain status fields generated by the
COMMAC channel to be processed by software.
Preliminary
Memory Access Layer 20-17
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