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Diffstat (limited to 'README.md')
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1 files changed, 46 insertions, 13 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: @@ -327,7 +330,46 @@ Verilog Attributes and non-standard features - The ``parameter`` and ``localparam`` attributes are used to mark wires that represent module parameters or localparams (when the HDL front-end - is run in -pwires mode). + is run in ``-pwires`` mode). + +- Wires marked with the ``hierconn`` attribute are connected to wires with the + same name (format ``cell_name.identifier``) when they are imported from + sub-modules by ``flatten``. + +- 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 ``invertible_pin`` attribute can be set on a port to mark it as + invertible via a cell parameter. The name of the inversion parameter + is specified as the value of this attribute. The value of the inversion + parameter must be of the same width as the port, with 1 indicating + an inverted bit and 0 indicating a non-inverted bit. + +- 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. + +- 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_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 @@ -405,15 +447,6 @@ 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_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 ============================================================== |