LSI Logic Confidential
FIFO and Buffer Operation
9-7
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
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Transfer stops.
•
If hardware flow control is being used with the Stop Address to break
up large transactions, then early packets must not occur.
9.4
FIFO and Buffer Operation
The FIFO is implemented as a dual-port 64-word by 64-bit memory
READ/WRITE port. Note that this section applies only to the Secondary
port.
For incoming transfers, data must not remain in the bitstream FIFO for
more than one millisecond. For cases where the FIFO buffer is not
completely filled within the one millisecond time constraint, the partially
filled buffer will be flushed to SDRAM.
The FIFO is flushed under two situations:
1.
There is no SDRAM access for one millisecond (only the contents in
the FIFO are flushed to SDRAM). It is possible that a few bytes may
remain in the buffer.
2.
Software clears the GO bit (the contents in the Packet register are
first moved into the FIFO, the GO bit is cleared to 0 if the Packet
register is not full, then the FIFO contents are flushed into SDRAM).
The remaining FIFO contents are discarded as outgoing bitstreams, if
software clears the GO bit. The bitstream is stored to or fetched from
SDRAM in the form of a circular buffer (see
Figure 9.6
Circular Buffer
Limit
Stop
Next < Stop
Next
Base
Next > Stop
Limit
Stop
Next
Base
Содержание DMN-8600
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