Refactor the AXI4 stream FIFO implementation.
- Define a single address generator which supports both single and double
clock mode. (synchronous and asynchronous)
- Fix FIFO status bits (empty/full). NOTE: In asynchronous mode the
flags can have a several clock cycle delay in function of the upstream/downstream
clock ratio.
- In synchronous none FIFO mode (ADDRESS_WIDTH==0), the module acts as
an AXI4 stream pipeline.
The FIFO functions in 'first fall through' mode, adjust the fifo level
generation so it take into account the valid data which sits on the bus,
waiting for ready, too.
For consistent simulation behavior it is recommended to annotate all source
files with a timescale. Add it to those where it is currently missing.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
In cases when a shallow FIFO is requested the synthesizer infers distributed RAM
instead of block RAMs. This can be an issue when the clocks of the FIFO are
asynchronous since a timing path is created though the LUTs which implement the
memory, resulting in timing failures. Ignoring timing through the path is not a
solution since would lead to metastability.
This does not happens with block RAMs.
The solution is to use the ad_mem (block RAM) in case of async clocks and letting
the synthesizer do it's job in case of sync clocks for optimal resource utilization.
All the hdl (verilog and vhdl) source files were updated. If a file did not
have any license, it was added into it. Files, which were generated by
a tool (like Matlab) or were took over from other source (like opencores.org),
were unchanged.
New license looks as follows:
Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
Each core or library found in this collection may have its own licensing terms.
The user should keep this in in mind while exploring these cores.
Redistribution and use in source and binary forms,
with or without modification of this file, are permitted under the terms of either
(at the option of the user):
1. The GNU General Public License version 2 as published by the
Free Software Foundation, which can be found in the top level directory, or at:
https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html
OR
2. An ADI specific BSD license as noted in the top level directory, or on-line at:
https://github.com/analogdevicesinc/hdl/blob/dev/LICENSE
Currently the BRAM and data registers in the util_axis_data are ungated
when the FIFO is ready to receive data. This good for high-performance
since it reduces the number of control signals. But it is bad from a power
point of view since it causes additional reads and writes.
Change the core gate the BRAM and data register if either the consumer is
not ready to accept data or the producer has no data to offer.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Add a room output on the input side that reports how many free entries the
FIFO has and a level output on the output side that reports how many valid
entries are in the FIFO.
Note that the level output is only accurate if the output of the FIFO is not
registered, otherwise it might be off by one.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Add a option to specify whether the FIFO should have a registered output
stage or not. This is useful if the user wants to implement that stage
itself.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Bring back the AXIS FIFO as a separate module instead of embedding it into
the DMAC module. This makes it possible to use it in other modules outside
of the DMAC.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Istvan Csomortani
Adrian Costina
Lars-Peter Clausen
Laszlo Nagy