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.\"  -*- nroff -*-
.\"  $Id: vbom.5 558 2014-06-01 22:20:51Z mueller $
.\"
.\" Copyright 2010-2013 by Walter F.J. Mueller <W.F.J.Mueller@gsi.de>
.\" 
.\" ------------------------------------------------------------------
.
.TH VBOM 2013-10-20 "Retro Project" "Retro Project Manual"
.\" ------------------------------------------------------------------
.SH NAME
vbom \- vhdl manifest file format - 'vhdl bill of material'
.
.\" ------------------------------------------------------------------
.SH DESCRIPTION
\fBvbom\fP files describe the sources needed to build a \fIvhdl\fP
entity. The source files are either given directly in case of libraries
or via other \fBvbom\fP's in case of instantiated components. 
They are used by \fBvbomconv\fP(1) to build project descriptions 
for synthesis and simulation tools.

\fBvbomconv\fP expects that the entries in the \fBvbom\fP's
are ordered, libraries first, than the components in the order they are
instantiated, finally the name of the associated source file.

The format has five types of lines:
.
.\" ----------------------------------------------
.IP \fBComments\fP 4
Each line starting with '\fB#\fP' is treated as comment and ignored.
.
.\" ----------------------------------------------
.IP "\fBFile names\fP"
Either source files or nested \fBvbom\fP's. The file names  must be given
as relative path name from the directory the \fBvbom\fP file is located in. 
Absolute path names are not allowed, nor is expansion of environment variables.

Currently three file types are accepted:
.RS
.IP "\fB.vbom\fP" 6
refers to a nested \fBvbom\fP. Usually used for instantiated components.
.
.IP "\fB.vhd\fP"
refers to a source file. Usually used for libraries refered to in 'use'
clauses, and as last file, the source file of the entity which is
described by this \fBvbom\fP file.
.
.IP "\fB.c\fP"
refers to the C source which implements a \fIvhdl\fP function or procedure
via the \fIvhpi\fP mechanism. Supported only in conjunction with \fBghdl\fP.
.
.RE
.
.
.\" ----------------------------------------------
.IP "\fBConditional file names\fP"
File names can be preceeded by a condition prefix of the form

.EX
   [\fItag\fP]filename
   [\fItag\fP,\fItag\fP,...]filename
.EE

The main purpose of this mechanism is to handle libraries and components 
which are only refered in 
.EX
    -- synthesis translate_off
    -- synthesis translate_on
.EE
sections and are used only for simulation.

Currently supported \fItag\fP names are
.RS
.RS 3
.PD 0
.IP "\fBxst\fP" 6
included in conjunction with xst synthesis
.IP "\fBghdl\fP"
included in conjunction with ghdl simulation
.IP "\fBisim\fP"
included in conjunction with isim simulation
.IP "\fBsim\fP"
included in conjunction with simulation (ghdl or isim)
.PD
.RE
.RE
.
.\" ----------------------------------------------
.IP "\fBLogical names\fP"
A logical name can be defined with
.EX
    <lname> = <filename> 
.EE
The first definition of a logical name encountered in the traversal of the
\fBvbom\fP's by \fBvbomconv\fP(1) is taken, all later definitions are ignored.

A logical name can be used with
.EX
    <lname> : <filename> 
.EE
The filename in the usage clause is the default used in case the
logical name wasn't defined before it is used.

Again, the filenames, either of type \fI.vhd\fP or \fI.vbom\fP ,
must be given as relative path name from the directory the \fBvbom\fP
file is located in.

.\" ----------------------------------------------
.IP \fBDirectives\fP
Directives start with a '\fB@\fP', currently implemented are:
.RS
.IP "\fB@top\fP:\fIname\fP" 4
Specifies the top level design name. Mainly used when it is different 
from the stem of the \fBvbom\fP file name.
.
.IP "\fB@lib\fP:\fIname\fP"
Specifies an additional system library. Allowed values for \fIname\fP are
\fIunisim\fP and \fIsimprim\fP. Currently used to generate the appropriate 
-L options for \fBghdl\fP commands, e.g. generated by the 
\fBvbomconv\fP action \fB\-\-ghdl_m\fP.
.
.IP "\fB@ucf_cpp\fP:\fIfile\fP"
Specifies that a \fIfile\fP.ucf file is to be generated by \fBcpp\fP(1)
from a \fIfile\fP.ucf_cpp source file. This allows to modularize ISE ucf files.
.RE
.
.\" ------------------------------------------------------------------
.SH EXAMPLES
.SS Simple entity
A simple vhdl entity named \fIbp_2l4l\fP which is defined in the source
file \fIbp_2l4l.vhd\fP, which uses the library \fIslvtypes\fP and
instantiates \fIbp_2line\fP and \fIbp_4line\fP, might have a 
\fIbp_2l4l.vbom\fP like
.PP
.EX
    # libs
    ../../vlib/slvtypes.vhd
    # components
    bp_2line.vbom
    bp_4line.vbom
    # design
    bp_2l4l.vhd
.EE
.PP
Note that the vhdl source file \fIbp_2l4l.vhd\fP is always given in the 
\fBvbom\fP file which describes this source file. 
The comments are put in by convention to help the human reader and 
are not interpreted by \fBvbomconv\fP.
.
.\" ------------------------------------------------------------------
.SH "SEE ALSO"
.BR vbomconv (1),
.BR ghdl (1),
.BR cpp (1)
.
.\" ------------------------------------------------------------------
.SH AUTHOR
Walter F.J. Mueller <W.F.J.Mueller@gsi.de>