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NAME

       asimut - A simulation tool for hardware descriptions

SYNOPSIS

       asimut [options] [root_file] [pattern_file] [result_file]

DESCRIPTION

       asimut  is  a  logical  simulation  tool  for hardware descriptions. It
       compiles and loads a complete  hardware  description  written  in  VHDL
       (Very  high  speed  integrated circuits Hardware Description Language).
       The hardware description may be structural (a hierarchy  of  instances)
       or  behavioural.  Only a subset of VHDL is supported. Descriptions that
       do not match this subset cause a syntax error during  compilation.  See
       vhdl(5) for detailed information about the supported subset of VHDL.

       Once  a  hardware  description is loaded, asimut looks for a simulation
       pattern description file. This file is to be  written  in  pat  format.
       The  file is compiled, loaded and linked with the hardware description.
       Then, the simulation is started. When patterns are processed, a  result
       file in pat format is produced.

       If  a  save  action  has been requested in the pattern description file
       (see pat (5)), asimut creates also a save file representing  the  state
       of  the  description  at the end of the simulation of the last pattern.
       The save file is named root_file.sav, where root_file is  the  name  of
       the description.

       The  save file can be used in a later simulation sequence to initialize
       the state of the (same)  hardware  description  before  the  simulation
       begins.   Using  this  mechanism,  a  large sequence of patterns can be
       breaked  onto  several  small  sequences,  each  one  initializing  the
       hardware  description  with  the  save  file resulted from the previous
       sequence.

       asimut reads several parameters from the environment variables :

       MBK_CATA_LIB        list  of  directories  containing  description  and
                           pattern  files  (using  $PATH  syntax). The default
                           path is the current directory (see mbk(1)).

       MBK_WORK_LIB        specifies  the  current  working   directory.   The
                           working  directory  idicates  the  place  where all
                           output files are written.

       MBK_CATAL_NAME      Indicates the file where the behavioral description
                           files  are  listed. This file is used to leaf cells
                           of a structural description.(see mbk(1))

       MBK_IN_LO           file extension for structural entity. (see mbk(1))

       VH_BEHSFX           list of file extensions  for  behavioural  entities
                           (using $PATH syntax). The default file extension is
                           vbe.

       VH_PATSFX           list of file  extensions  for  pattern  description
                           entities  (using  $PATH  syntax).  The default file
                           extension is pat.

       VH_DLYSFX           list of  file  extensions  for  delays  description
                           entities  (using  $PATH  syntax).  The default file
                           extension is dly.

       VH_MAXERR           maximum number of errors allowed during  simulation
                           phase.  If  the  number  of  errors  occured during
                           simulation  reaches  VH_MAXERR,  asimut  stops  the
                           simulation  at  the  end  of processing the current
                           pattern. Patterns  following  the  current  pattern
                           remain unprocessed and are reproduced in the result
                           file.  The default value of VH_MAXERR is 10.

       root_file is the name of the description.

       By default asimut looks for  a  structural  description.  It  uses  the
       MBK_IN_LO  environment  variables  to  identify both the format and the
       extension of structural description  files.  To  load  structural  VHDL
       files MBK_IN_LO must be set to vst.

       To  load a pure behavioural description -b option must be specified. In
       such a case asimut  loads  a  data  flow  VHDL  description  file.  The
       VH_BEHSFX environment variable gives the extensions to be used.

       pattern_file  is  the  entity name of the pattern description. The file
       containing this entity must be named pattern_file.ext ,  where  ext  is
       one of the extension specified in VH_PATSFX.

       result_file is the result file produced by asimut. The result file is a
       pattern description file with the extension specified by VH_PATSFX.

OPTIONS

       -b                  consider the root_file description as a behavioural
                           description

       -backdelay [min, max, typ] delay_file
                           use  file delay_file.ext for delays backannotation,
                           where ext is one  of  the  extension  specified  in
                           VH_DLYSFX.

       -bdd                use  BDDs  (Binary  Decision  Diagram) to represent
                           expressions. Using this option makes the simulation
                           be   two   times   faster   but   increases  memory
                           requirement

       -c                  run only the compilation stage

       -core core_file     at the first error encountered, dump the  state  of
                           the  circuit  in both an ascii file (suffixed .cor)
                           and a binary save file (suffixed .sav) which can be
                           used  as  initialization file in a further session.
                           If the -nores option is specified a pattern file is
                           also produced.

       -dbg[sbpldc]        call the debugger (developper usage)

       -defaultdelay (-dd) only null delays (no after clause in the VHDL file)
                           are changed if backannotated delays or fixed delays
                           are specified.

       -fixeddelay value (-fd value)
                           all delays of the description are fixed to value.

       -h                  display this help file

       -i value            initialize  all  signals  of  the  description with
                           value. Value can be 0 or 1

       -i save_file        read a save file and use it to initialize the state
                           of  the  description  before  processing  the first
                           pattern (the file name cannot be 1 nor 0)

       -inspect instance_name
                           produce  a  pattern  file  corresponding   to   the
                           interface  of  the instance identified by instance-
                           name

       -l n                print at most n characters for pattern labels.  The
                           default value for n is 15.

       -nores              do not generate result file

       -p n                load  at  most  n  patterns from input pattern file
                           each  time.  Using  this  feature  reduces   memory
                           allocation  when  a great number of patterns are to
                           be simulated. In addition after the n patterns have
                           been processed, the simulation result is printed in
                           the result pattern file. The default value for n is
                           0 which makes the whole pattern file be loaded.

       -t                  trace signals when making BDDs (developper usage).

       -transport          use transport delay model (default is inertial).

       -zerodelay (-zd)    all the delays of the VHDL description are supposed
                           to be null delays.

EXAMPLE

       asimut -b -i init_add adder_32 adder_patterns res_add

       simulates  a  behavioural  description   held   in   the   file   named
       'adder_32.vbe   using   the   pattern  file  `adder_patterns.pat'.  The
       simulation results is written into 'res_add.pat' and the description is
       initialized with the values contained in 'init_add.sav'.

DIAGNOSTICS

       Register  initializations in the pattern file allows changing the value
       of a register into a  known  value.  However,  using  this  feature  to
       initialize  a  register  before  executing  the  first  pattern  is not
       recommended. Registers value (defined by the initialization  statement)
       may  be  overwritten  since description has not a coherent state before
       the first pattern.

SEE ALSO

       vhdl(5), pat(5), genpat(1), mbk(1)