There is no need to multiply item names, it is a rudiment of my very
first addition to nextpnr.
Fully compatible with older versions of Apicula.
Note: the cosmetic changes in lines with RAM are not my initiative, but
the result of applying clang-format.
Signed-off-by: YRabbit <rabbit@yrabbit.cyou>
Gowin chips have a highly sophisticated system of long wires that are
wired to each cell and allow the clock or logic to spread quickly.
This commit implements some of the capabilities of the long wire system
for quadrants, leaving out the fine-tuning of them for each column.
To make use of the long wire system, the specified wire is cut at the
driver and a special cell is placed between the driver and the rest of
the wire.
* VCC and GND can not use long wires because they are in every cell and
there is no point in using a net
* Long wire numbers can be specified manually or assigned automatically.
* The route from the driver to the port of the new cell can be quite
long, this will have to be solved somehow.
* It might make sense to add a mechanism for automatically finding
candidates for long wires.
Signed-off-by: YRabbit <rabbit@yrabbit.cyou>
GSR is added automatically if it was not instantiated by the user explicitly.
Compatible with old apicula bases, the functionality does not work, but
the crash does not happen --- just a warning.
Signed-off-by: YRabbit <rabbit@yrabbit.cyou>
Some models have I/O cells that are IOBUFs, and other types (IBUFs and
OBUFs) are obtained by feeding 1 or 0 to the OEN input. This is done
with general-purpose routing so it's best to do it here to avoid
conflicts.
For this purpose, in the new bases, these special cells are of type IOBS
(IOB Simplified).
The proposed changes are compatible with bases of previous versions of
Apycula and do not require changing .CST constraint files.
Signed-off-by: YRabbit <rabbit@yrabbit.cyou>
* A hardwired MUX within each logical cell is used.
* The delay is equal 0.
* No user placement constraints.
* The output route contains dummy PIPs. They are ignored by gowin_pack, but it may be worth removing them.
Signed-off-by: YRabbit <rabbit@yrabbit.cyou>
