tour.gml

开放源码的编译器open watcom 1.6.0版的源代码

.chap Project Overview

This document serves as an introduction and a guide for developers of
the Open Watcom compilers and tools. It is not particularly useful for
the users (who are also developers) of Open Watcom compilers &mdash
they are encouraged to read the User's Guide, Programmer's Guide,
C Language Reference and other user oriented books.
.np
It should not be assumed that this book is in any way final or the
ultimate reference. Readers are encouraged to add, change and modify this
document to better reflect evolution of the Open Watcom project.

.section History
.*
.np
.ix 'history'
.ix 'WATFOR'
The history of the Open Watcom project is rather long, in terms of
Interned years it would probably span millennia. The origins can be
traced back to 1965. That summer a team of undergraduate students
at the University of Waterloo develped a FORTRAN compiler (called
WATFOR) that ran on the University's IBM 7040 systems. The compiler
was soon ported to IBM 360 and later to the famous DEC PDP-11.
.np
.ix 'WATFOR-77'
In early 1980s a brand new version of the compiler was created
that supported the FORTRAN 77 language. It ran on two platforms,
the IBM 370 and the emerging IBM PC. The PC version of WATFOR-77
was finished in 1985 and in the same year support for Japanese was
added. In 1986, WATFOR-77 was ported to the QNX operating system.
.np
The early compilers were written in a portable language called
WSL or Watcom Systems Language. In late 1980s the developers
rewrote the existing code in C and from then on all new developments
were done on C, later with traces of C++ here and there.
.np
In parallel to the FORTRAN compilers Watcom developed optimizing
C compilers. When the first PC version (Watcom C 6.0) was introduced
in 1987, it immediately attracted attention by producing faster code
than other compilers available at that time.
.np
In 1988 work started on an advanced highly optimizing code generator
that supported both the C language and FORTRAN and was portable across
multiple platforms. Generation of tight code, availability on multiple
platforms (DOS, Windows, OS/2 and Windows NT in one package) and the
ability to cross-compile made Watcom C and C++ compilers quite popular
in mid-1990s. Around 1993-1996, nearly all DOS games were developed
with Watcom C, including famous titles such as DOOM, Descent or Duke
Nukem 3D.
.np
.ix 'VX-REXX'
Watcom International, Inc. had other successful products besides its
highly acclaimed compilers. VX-REXX was a popular GUI RAD tool for
OS/2 and Watcom SQL was a cross-platform "embeddable" SQL database.
.np
.ix 'PowerSoft'
In mid-1990s, Watcom International, Inc. was acquired by PowerSoft, the
maker of Power++, PowerDesigner and other GUI RAD tools for the Windows
platform. PowerSoft used Watcom compiler technology as a back-end for
their GUI tools besides continuing to market and develop existing
Watcom tools.
.np
.ix 'Sybase'
PowerSoft itself had merged with Sybase, Inc. in 1994. PowerSoft's
development tools nicely complemented Sybase's database servers.
Sybase was also interested in Watcom SQL which was enhanced and turned
into Sybase SQL Anywhere.
.np
Sybase continued to sell Watcom C/C++ and FORTRAN compilers version 11 but
it was obvious that Sybase couldn't compete with Microsoft in the
languages market. Sybase decided to end-of-life the Watcom compilers
effective 2000.
.np
.ix 'SciTech'
But that's not the end of the story. Many customers did not want to give
up the Watcom compilers because there was no suitable replacement in many
areas. One of these customers was Kendall Bennett of SciTech Software, Inc.
SciTech entered into negotiations with Sybase and in an unprecedented move,
Sybase agreed upon open sourcing the Watcom compilers and tools. One of
the reasons why this was possible at all was the fact that Watcom had very
little reliance on third-party tools and source code and had developed
practically everything in-house, from YACC to IDE.
.np
The process of opening the source was longer than originally anticipated
(all software related projects tend to work out this way for some
inexplicable reason) but in the first half of 2002, the source was finally
made available under the Sybase Open Watcom Public License version 1.0.


.section Guided Tour
.*
.np
This section will take you on a guided tour of the Open Watcom source tree,
presenting an overview of its structure and highlighting some of the more
memorable sights.
.np
The Open Watcom directory structure mostly mirrors the layout used by
the Watcom/Sybase build server but it has been cleaned up, straightened
out and unified, although there still may be some warts.
.np
The root of the Open Watcom directory tree can be in the root of
any drive (if your OS uses drive letters) or in any directory, for
instance
.id e:\ow.
Long filenames are not recommended if compatibility with DOS tools is
desired. Directory names which include spaces are highly discouraged in
any case.
.np
The main subdirectories in the Open Watcom root are the following:
.begnote
.note bat
currently contains mostly useless batch files and several useful ones.
One extremely important file lives here:
.us makeinit.
This file controls the operation of wmake and is the key to understanding
of the build process. Since wmake looks for
.us makeinit
along the
.id PATH,
the
.us bat
directory should be placed at or near the start of your
.id PATH
environment variable.
.note bin, binp
contains miscellaneous binaries used in the build process. The binp directory
contains OS/2 executables, bin contains DOS or Win32 executables.
.note bld
is
.us the
directory where it's at. It contains all the Open Watcom source code. It is
so important (and huge) that it deserves its own section.
.note docs
contains source files for the Open Watcom documentation as well as binaries
needed to translate the sources into PostScript, HTML or various online
help formats. The source files of this document are stored under this directory.
For more information please refer the the chapter entitled Documentation
later in this manual.
.note rel2
is the "release" directory is where the binaries and other files produced
in the course of the build process end up. The structure of this directory
mirrors the
.us WATCOM
directory of a typical Open Watcom installation.
.endnote


.section The bld directory
.*
.np
.ix 'bld'
Following is a brief description of all subdirectories of bld. Each subdirectory
roughly corresponds to one "project". There's a lot of projects!
.begnote
.note as
the Alpha AXP and PowerPC assembler. The x86 assembler lives separately.
.note aui
user interface library employed by the debugger and profiler.
.note bdiff
binary diff and patch utilities.
.note bmp2eps
a utility for converting Windows bitmap files into EPS format, used for
building documentation.
.note brinfo
part of the C++ source browser.
.note browser
the GUI C++ source browser.
.note build
directory holding build related files such as binaries used internally during
build process and several master make include files which lie at the heart of
the build system. Worth visiting!
.note builder
builder tool controlled by those
.us lang.ctl
files that are all over the place.
.note causeway
the popular CauseWay DOS extender, in a form buildable with Open Watcom tools.
.note cc
the C compiler front end.
.note cfloat
utility function for conversion between various floating point binary formats.
.note cg
Open Watcom code generators, the heart of the compilers. These are shared by
all languages (C, C++, FORTRAN). Currently supported targets are 16-bit and
32-bit x86 as well as Alpha AXP.
.note clib
the C runtime library. Pretty big project in itself.
.note cmdedit
command line editing utilities, pretty much obsolete.
.note comp_cfg
compiler configuration header files for various targets.
.note cpp
a simple C style preprocessor used by several other projects.
.note ctest
C compiler regression tests. Run them often.
.note cvpack
the CV pack utility (for CodeView style debugging information).
.note diff
Open Watcom version of the popular utility.
.note dig
files used primarily by the debugger &mdash this directory contains files that
are shared between debugger, profiler, trap files and Dr. Watcom.
.note dip
Debug Information Processors, used by debugger. The DIPs provide an
interface between the debugger and various debug information formats.
.note dmpobj
a simple OMF dump utility.
.note dwarf
library for reading and writing DWARF style debugging information.
.note editdll
interface modules between the IDE and external editors.
.note emu
80387 emulator library.
.note emu86
8087 emulator library.
.note f77
FORTRAN 77 compiler front end, runtime library, regression tests and
samples. All the FORTRAN stuff is crowded in there.
.note fe_misc