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Diffstat (limited to 'README.md')
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1 files changed, 38 insertions, 3 deletions
@@ -1,7 +1,7 @@ ``` yosys -- Yosys Open SYnthesis Suite -Copyright (C) 2012 - 2018 Clifford Wolf <clifford@clifford.at> +Copyright (C) 2012 - 2019 Clifford Wolf <clifford@clifford.at> Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above @@ -69,11 +69,14 @@ prerequisites for building yosys: graphviz xdot pkg-config python3 libboost-system-dev \ libboost-python-dev libboost-filesystem-dev zlib1g-dev -Similarily, on Mac OS X MacPorts or Homebrew can be used to install dependencies: +Similarily, on Mac OS X Homebrew can be used to install dependencies: $ brew tap Homebrew/bundle && brew bundle + +or MacPorts: + $ sudo port install bison flex readline gawk libffi \ - git graphviz pkgconfig python36 boost zlib + git graphviz pkgconfig python36 boost zlib tcl On FreeBSD use the following command to install all prerequisites: @@ -329,6 +332,21 @@ Verilog Attributes and non-standard features that represent module parameters or localparams (when the HDL front-end is run in -pwires mode). +- The ``clkbuf_driver`` attribute can be set on an output port of a blackbox + module to mark it as a clock buffer output, and thus prevent ``clkbufmap`` + from inserting another clock buffer on a net driven by such output. + +- The ``clkbuf_sink`` attribute can be set on an input port of a module to + request clock buffer insertion by the ``clkbufmap`` pass. + +- The ``clkbuf_inhibit`` is the default attribute to set on a wire to prevent + automatic clock buffer insertion by ``clkbufmap``. This behaviour can be + overridden by providing a custom selection to ``clkbufmap``. + +- The ``iopad_external_pin`` attribute on a blackbox module's port marks + it as the external-facing pin of an I/O pad, and prevents ``iopadmap`` + from inserting another pad cell on it. + - 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 @@ -405,6 +423,23 @@ Verilog Attributes and non-standard features blackboxes and whiteboxes. Use ``read_verilog -specify`` to enable this functionality. (By default specify .. endspecify blocks are ignored.) +- 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. + Non-standard or SystemVerilog features for formal verification ============================================================== |