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Diffstat (limited to 'README.md')
| -rw-r--r-- | README.md | 13 |
1 files changed, 5 insertions, 8 deletions
@@ -412,19 +412,16 @@ Verilog Attributes and non-standard features blackbox or whitebox definition to a corresponding entry in a `abc9` box-file. -- The port attribute ``abc_scc_break`` indicates a module input port that will - be treated as a primary output during `abc9` techmapping. Doing so eliminates - the possibility of a strongly-connected component (i.e. a combinatorial loop) - existing. Typically, this is specified for sequential inputs on otherwise - combinatorial boxes -- for example, applying ``abc_scc_break`` onto the `D` - port of a LUTRAM cell prevents `abc9` from interpreting any `Q` -> `D` paths - as a combinatorial loop. - - The port attribute ``abc_carry`` marks the carry-in (if an input port) and carry-out (if output port) ports of a box. This information is necessary for `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 ``abc_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 techmapping. + Non-standard or SystemVerilog features for formal verification ============================================================== |