** Release Notes for Icarus Verilog 0.8.3
This is a new release of the stable 0.8 branch. The changes from 0.8.2
are intended to be evolutionary, rather then revolutionary, to enhance
the stability of the branch.
Various simulator bugs have been fixed, including (but not limited to):
- Detect overrun of timescale vs. precision
- Handle more operators in constant expressions
- Various ivl crashes and panics fixed.
- Some performance bottlenecks have been fixed.
- Various tool compilation problems have been fixed.
Also, the internal synthesizer (for synthesis targets) has been
considerably improved. NOTE that the code generators have not been
improved to take advantage of all the changes here, so there is work
yet to be done.
The mingw build process for compiling in Windows has been reworked. It
is now possible (indeed preferable) to compile fully native Icarus
Verilog binaries on Windows with no Cygwin tools at all.
The current release is a considerable improvement over the previous stable
release. It includes 20 months of fixes and language coverage improvements.
For a complete history of changes, see the release notes for individual
snapshots between the 0.7 and 0.8 releases found at
ftp://ftp.icarus.com/pub/eda/verilog/snapshots/pre-0.8
A brief list of highlights:
- Support for advanced standard data types such as real,
- Lots more language support in general,
- Kernel of an extensible, interactive debugger is new,
- More complete support for user supplied system functions and tasks,
including PLI system functions with various return value types,
- Better standards compliance for core system tasks and functions in
general, including some Verilog 2001 file I/O support, and
- Performance improvements in general.
This release represents many bug fixes, expanded language coverage,
greatly enhanced xilinx fpga synthesis and several performance enhancements.
The complete list is rather long.
WHAT'S NEW SINCE 0.5?
Quite a lot. Innumerable bugs have been fixed, and standards coverage
has been improved significantly. Warning and error messages have been
improved, and so has compile performance. Gate delays, strength
modeling, and floating point delays have all improved since the 0.5
release. If you had trouble with the 0.5 release, the 0.6 release
probably fixes your problem.
Support for large designs spanning multiple files has been improved
dramatically. The usual preprocessor inclusion method still works, but
The 0.6 release adds command files for keeping source file lists, and
automatic library searches for missing modules. The library mechinisms
are compatible with commercial tools, and commercial module libraries
can be used with Icarus Verilog.
Many compiler limitations related to the size and complexity of large
designs have been relaxed or eliminated. There are no known design
size limitations remaining in the compiler. Icarus Verilog should be
able to handle any design that you have the patience to compile.
* The Big Change: VVP
Past versions of Icarus Verilog performed simulation by compiling the
Verilog design to intermediate C++ code, then in turn compiling that
C++ (usually with G++) to a binary executable. This program was then
executed to actually run the simulation.
The 0.5 compiler, however, uses a custom internal language called
"vvp." The vvp code generator writes a program in the vvp language
that the vvp interpreter executes. This gets runtime performance
similar to the older vvm method, but compile times are much faster.
The result of this change is that there is a new program, ``vvp'',
that is installed with the existing ``iverilog'' compiler. This
program actually executes the simulation generated by the vvp code
generator.
There are manual pages for the iverilog command and the new vvp
command, as well as a QUICK_START document to help you run your first
simulation.
* What Else Is New
The compiler itself is now a lot more robust. While it still does not
compile and understand the entire IEEE1364 standard, the compiler is
less likely to crash on bad input, gives better error messages, and
has generally been cleaned up.
