Commit ccc12d3c authored by William D. Jones's avatar William D. Jones Committed by Sébastien Bourdeauducq
Browse files

lattice/icestorm: Clarify supported/unsupported attributes.

parent 87bba69a
......@@ -87,17 +87,20 @@ icepack {icepack_opt} {build_name}.txt {build_name}.bin{fail_stmt}
class LatticeIceStormToolchain:
attr_translate = {
"keep": ("keep", "true"),
"no_retiming": None, # yosys does not do retiming
"async_reg": None,
# The next 5 attributes are Vivado-specific. Ignore.
"mr_ff": None,
"no_retiming": None, # yosys/arachne-pnr does not do retiming.
"async_reg": None, # yosys has no equivalent, and arachne-pnr
# wouldn't take advantage of it anyway.
# While custom constraints are supported in yosys, neither
# arachne-pnr nor icetime currently can take advantage of them
# to add fine-grained timing constraints.
"mr_ff": None, # user-defined attribute
"mr_false_path": None, # user-defined attribute
"ars_ff1": None, # user-defined attribute
"ars_ff2": None, # user-defined attribute
"ars_false_path": None, # user-defined attribute
# Shift reg primitive issues are ISE-specific. Ignore.
# ice40 does not have a shift register primitive.
"no_shreg_extract": None
}
......
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