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Describe the compilation major steps.

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steve 2001-03-21 05:12:15 +00:00
parent 27e717839a
commit e24facfaf6
1 changed files with 48 additions and 2 deletions
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vvp/README.txt
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@ -1,7 +1,7 @@
/*
* Copyright (c) 2001 Stephen Williams (steve@icarus.com)
*
* $Id: README.txt,v 1.5 2001/03/20 06:16:23 steve Exp $
* $Id: README.txt,v 1.6 2001/03/21 05:12:15 steve Exp $
*/
VVP SIMULATION ENGINE
@ -243,6 +243,50 @@ is concerned, the functor net is a blob of structure that it pokes and
prods via certain functor access instructions.
VVP COMPILATION AND EXECUTION
The vvp program operates in a few steps:
1) Initialization
Data structures are cleared to empty, and tables are
readied for compilation.
2) Compilation
The input file is read and compiled. Symbol tables are
build up as needed, objects are allocated and linked
together.
3) Cleanup
Symbol tables and other resources used only for
compilation are released to reduce the memory
footprint.
4) Simulation
Event simulation is run.
The initialization step is performed by the compile_init() function in
compile.cc. This function in turn calls all the *_init() functions in
other parts of the source that need initialization for compile. All
the various sub-init functions are called <foo>_init().
Compilation is controlled by the parser, it parse.y. As the parser
reads and parses input, the compilation proceeds in the rules by
calling various compile_* functions. All these functions live in the
compile.cc file. Compilation calls other sections of the code as
needed.
When the parser completes compilation, compile_cleanup() is called to
finish the compilation process. Unresolved references are completed,
then all the symbol tables and other compile-time-only resources are
released. Once compile_cleanup() returns, there is no more use for the
parser for the function in compile.cc.
After cleanup, the simulation is started. This is done by executing
the schedule_simulate() function. This does any final setup and starts
the simulation running and the event queue running.
HOW TO GET FROM THERE TO HERE
The vvp simulation engine is designed to be able to take as input a
@ -289,7 +333,9 @@ Each bit of a variable is created by a ``.var'' statement. For example:
becomes:
a .var;
a .var "a", 0, 0;
/*
* Copyright (c) 2001 Stephen Williams (steve@icarus.com)