Current reality of what is supported.
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README.txt
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README.txt
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@ -10,14 +10,15 @@ currently handle a mix of structural and behavioral constructs. For a
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view of the current state of Icarus Verilog, see its home page at
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<http://www.icarus.com/eda/verilog>.
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IVL is not aimed at being a simulator in the traditional sense, but a
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compiler that generates code employed by back-end tools. These back-
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end tools currently include a simulator written in C++ called VVM
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and an XNF (Xilinx Netlist Format) generator. See "vvm.txt" and
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"xnf.txt" for further details on these back-end processors. In the
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future, backends are expected for EDIF/LPM, structural Verilog, etc.
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Icarus Verilog is not aimed at being a simulator in the traditional
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sense, but a compiler that generates code employed by back-end
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tools. These back- end tools currently include a simulator written in
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C++ called VVM and an XNF (Xilinx Netlist Format) generator. See
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"vvm.txt" and "xnf.txt" for further details on these back-end
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processors. In the future, backends are expected for EDIF/LPM,
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structural Verilog, etc.
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2.0 Building/Installing IVL From Source
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2.0 Building/Installing Icarus Verilog From Source
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If you are starting from source, the build process is designed to be
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as simple as practical. Someone basically familiar with the target
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@ -36,9 +37,9 @@ on a UNIX-like system:
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satisfactory make.
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- ISO C++ Compiler
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The ivl program is written in C++ and makes use of templates
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and some of the standard C++ library. egcs compilers with
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the associated libstdc++ are known to work.
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The ivl and ivlpp programs are written in C++ and makes use
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of templates and some of the standard C++ library. egcs
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compilers with the associated libstdc++ are known to work.
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- bison
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@ -66,7 +67,7 @@ root.
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make install
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3.0 How IVL Works
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3.0 How Icarus Verilog Works
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This tool includes a parser which reads in Verilog (plus extensions)
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and generates an internal netlist. The netlist is passed to various
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@ -115,12 +116,10 @@ first, followed by the structural and behavioral elaboration.
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3.3.1 Scope Elaboration
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This pass scans through the pform looking for scopes and
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parameters. A tree of NetScope objects is built up and placed in the
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Design object, with the root module represented by the root NetScope
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object.
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The elab_scope.cc and elab_pexpr.cc files contain most of the code for
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This pass scans through the pform looking for scopes and parameters. A
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tree of NetScope objects is built up and placed in the Design object,
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with the root module represented by the root NetScope object. The
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elab_scope.cc and elab_pexpr.cc files contain most of the code for
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handling this phase.
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The tail of the elaborate_scope behavior (after the pform is
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@ -131,7 +130,7 @@ the defparam overrides are applied to the parameters.
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3.3.2 Netlist Elaboration
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After the scopes and parameters are generated and the NetScope tree
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fully formed, the elaboration runs through teh pform again, this time
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fully formed, the elaboration runs through the pform again, this time
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generating the structural and behavioral netlist. Parameters are
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elaborated and evaluated by now so all the constants of code
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generation are now known locally, so the netlist can be generated by
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@ -173,7 +172,7 @@ done in a friendly way. See the iverilog(1) man page for usage details.
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4.1 Running IVL Directly
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The ivl command is the compiler driver, that invokes the parser,
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optimization functions and the code generator.
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optimization functions and the code generator, but not the preprocessor.
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Usage: ivl <options>... file
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ivl -h
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@ -305,7 +304,7 @@ To run the program
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5.0 Unsupported Constructs
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IVL is in development - as such it still only supports a (growing) subset
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of verilog. Below is a description of some of the currently unsupported
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of Verilog. Below is a description of some of the currently unsupported
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verilog features. This list is not exhaustive, and does not account
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for errors in the compiler. See the Icarus Verilog web page for the
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current state of support for Verilog.
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@ -327,20 +326,10 @@ current state of support for Verilog.
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assign foo = user_function(a,b); // sorry
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always @(a or b) foo = user_function(a,b); // OK
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- multiplicative operators (*, /, %) are not supported in
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general. They do work if the compiler can evaluate them at compile
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time.
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assign foo = a * b; // sorry
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always @(a or b) foo = a * b; // sorry
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- real data type not supported.
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- system functions are not supported. (User defined functions are
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supported, and system tasks are supported.)
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assign foo = $some_function(a,b); // sorry
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always @(a or b) foo = $some_function(a,b); // sorry
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- System functions are supported, but the compiler presumes that
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they return 32 bits. This is the typical case.
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- non-constant delay expressions, i.e.:
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