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Diffstat (limited to 'README.md')
| -rw-r--r-- | README.md | 13 |
1 files changed, 9 insertions, 4 deletions
@@ -373,10 +373,15 @@ Verilog Attributes and non-standard features `abc9` to preserve the integrity of carry-chains. Specifying this attribute onto a bus port will affect only its most significant bit. -- The port attribute ``abc9_arrival`` specifies an integer (for output ports - only) to be used as the arrival time of this sequential port. It can be used, - for example, to specify the clk-to-Q delay of a flip-flop for consideration - during `abc9` techmapping. +- The output port attribute ``abc9_arrival`` specifies an integer, or a string + of space-separated integers to be used as the arrival time of this blackbox + port. It can be used, for example, to specify the clk-to-Q delay of a flip- + flop output for consideration during `abc9` techmapping. + +- The input port attribute ``abc9_requiredl`` specifies an integer, or a string + of space-separated integers to be used as the required time of this blackbox + port. It can be used, for example, to specify the setup-time of a flip-flop + input for consideration during `abc9` techmapping. - The module attribute ``abc9_flop`` is a boolean marking the module as a flip-flop. This allows `abc9` to analyse its contents in order to perform |