mirror of https://github.com/YosysHQ/nextpnr.git
d966fc5dcb
The ALUs in the GW5A series have undergone changes compared to previous
chips.
The most significant change is the appearance of an input MUX for
carry — it is now possible to switch between VCC, GND, and COUT of the
previous ALU, as well as generate carry in logic.
The granularity of resource allocation for ALUs has also changed — it is
now possible to use each half of a slice independently for ALUs.
Not all new features are reflected in this commit:
- since there is one CIN MUX for every six ALUs and it only works for
ALUs with index 0, the new granularity is not very useful: the head of
the chain can only be placed in the zero ALU. It is possible to gain one
LUT by allocating ALUs in odd numbers, but we will leave that for the
future.
- using CIN MUX to generate carry in logic is interesting, but we have
not yet been able to get the vendor IDE to generate such a
configuration to figure out which wires are used, so for now we are
leaving the old behavior in logic with the allocation of a specialized
head ALU.
Signed-off-by: YRabbit <rabbit@yrabbit.cyou>
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| .. | ||
| himbaechel_dbgen | ||
| uarch | ||
| .gitignore | ||
| CMakeLists.txt | ||
| arch.cc | ||
| arch.h | ||
| arch_pybindings.cc | ||
| arch_pybindings.h | ||
| archdefs.h | ||
| chipdb.h | ||
| himbaechel_api.cc | ||
| himbaechel_api.h | ||
| himbaechel_constids.h | ||
| himbaechel_gfxids.h | ||
| himbaechel_helpers.cc | ||
| himbaechel_helpers.h | ||
| main.cc | ||