From: Eddie Hung Date: Fri, 30 Aug 2019 19:28:35 +0000 (-0700) Subject: Merge remote-tracking branch 'origin/master' into xaig_arrival X-Git-Tag: working-ls180~1075^2^2~8 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=c7f1ccbcb0b36093f619bbbd3c5dd621161134de;p=yosys.git Merge remote-tracking branch 'origin/master' into xaig_arrival --- c7f1ccbcb0b36093f619bbbd3c5dd621161134de diff --cc README.md index 9e1761ec4,e0a95a9d5..6ac321c1f --- a/README.md +++ b/README.md @@@ -347,6 -347,23 +347,20 @@@ Verilog Attributes and non-standard fea it as the external-facing pin of an I/O pad, and prevents ``iopadmap`` from inserting another pad cell on it. + - The module attribute ``abc_box_id`` specifies a positive integer linking a + 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. ++ - In addition to the ``(* ... *)`` attribute syntax, Yosys supports the non-standard ``{* ... *}`` attribute syntax to set default attributes for everything that comes after the ``{* ... *}`` statement. (Reset