[Home]
[Search]
[CTG]
[RTL]
[IDDE]
Last update Nov 7, 2004
OPTLINK
OPTLINK, the Digital Mars linker, links object files and libraries to
produce an executable program or DLL for DOS, Windows 3.x, or Win32.
For simple programs, the link step can be run automatically
by the compiler. For more complex applications that need close control
over how the program is linked, run OPTLINK as a separate step.
To control running the linker from the IDDE,
set options in the Linker subpage on the
Build page of the IDDE's Project Settings dialog box.
Overview
OPTLINK is a super-fast, high-capacity program linker. It is designed
for use by professional programmers to efficiently create both
standard .exe and .com executable files for use with MS-DOS and
segmented .exe files (segmented executable) and dynamic link
libraries (.dll) for use with Windows and Win32 in significantly
less time than is required by other linkers.
OPTLINK derives its spectacular speed from being written entirely in hand-
tuned assembly language, making maximal use of multithreading and processor
scheduling. It does full links faster than more pedestrian linkers do
incremental links.
OPTLINK combines object (.obj) and library (.lib) files into a
single file that is
executable by the operating system. OPTLINK can optionally
create memory maps and symbol tables that are useful for debugging.
OPTLINK works with modules in Intel OMF format (.obj file),
including those generated by standard assemblers, compilers and
standard object module libraries. The output files produced have all
address assignments resolved and are in one of three standard
formats:
- 16 bit DOS .exe relocatable executable MZ format (MSDOS)
- 16 bit .com/.sys/.bin memory image format (MSDOS)
- 16 bit segmented .exe NE format (Windows 3.x)
- 32 bit .exe PE format (PE) (DOSX, Win32)
All available memory is used by OPTLINK when linking
executable programs. For 16-bit programs, the number of program
description objects that can be accommodated is limited to 64KB for
each kind of object (PUBLIC, LIBRARY, SEGMENT, and so on). If
memory space is inadequate, the program descriptions are
automatically paged out to disk files which are then deleted once the
link process completes.
These features combine to create an environment in which you can
create large programs, despite apparent memory constraints.
Features
Although compatibility with existing linkers was a prime objective in
the design of OPTLINK, the product sets itself apart from other
linkers with a number of exclusive features. OPTLINK features
include:
- Speed
Executes faster than any other method for creating
executable files. Removal of duplicate records (CVPACK)
is built in.
- Capacity
Successfully builds huge applications, including debug
information.
- Smart linking
Unlike others, recursively eliminates unreferenced code.
Also eliminates unreferenced uninitialized global
variables, see /PACKFUNCTIONS.
- Efficient program generation options
Builds smaller, more efficient, faster loading and even
faster running 16-bit programs by packing code and data,
plus converting intra-segment far calls to near calls, see
/PACKCODE, /PACKDATA, /EXEPACK,
/FARCALLTRANSLATION.
- Cross referencing
Optionally included within map output. Every global
symbol and the module name( s) of where defined and
referenced is listed, see /XREF.
- Environment use
Dedicated environment variable usage simplifies searches.
- Virtual memory system
When DOS hosted, automatically uses EMS memory, XMS
memory, or disk storage, whichever is available.
Option switch precedence
Switches are read and processed in lexical order.
Any subsequent switch overrides any previous switch setting.
- The optlinks.cfg configuration file.
- The LINK environment variable.
- The OPTLINKS environment variable.
- Command line and indirect response file in the order
supplied. Recognizes the most recent switch syntax
selected.
Configuration
To specify default operating parameters not available through the
IDDE, modify the file named optlinks.cfg. You can supply
option switches that you may regularly use or desire as default.
When called, optlinks.cfg, an ASCII file, is read by OPTLINK
from its home directory, unless optlinks.cfg already exists in the
current directory. OPTLINK recognizes the "#" as a comment
character and thus ignores the remainder of the line.
Environment Variables
The environment variable names recognized are LIB, TMP, LINK,
OPTLINKS and OBJ. OPTLINK also searches the PATH environment
variable to locate certain executable files. The environment variables
are typically defined in autoexec.bat or another batch file.
- LIB
- Supplies paths to search for libraries, object files,
and resource files.
See also /SCANLIB.
- TMP
- Supplies a path used by OPTLINK for its virtual memory file.
Otherwise, the current directory is used. OPTLINK's performance
can be severely slowed when its virtual memory file must be stored
across a network.
- LINK
- Supplies linker switch settings. Recognized for Microsoft LINK
compatibility. See also /SCANLINK.
- OPTLINKS
- Supplies linker switch settings. OPTLINKS is scanned after the LINK
variable and can override any previous settings specified.
- OBJ
- Supplies paths to be searched by OPTLINK for .obj files not found
in the current working directory. Paths specified by OBJ are always
searched before any paths specified by the LIB environment
variable.
- PATH
- Supplies paths to be searched by OPTLINK for any stub .exe file
specified in the .def file.
For example, to select the linker option /IGNORECASE as the
default, the following command could be used:
set OPTLINKS=/IG
The environment variables can be overridden by command line
input. Every switch can be changed, since it has an opposite.
Versions of OPTLINK
- linknd.dll DLL version for use in IDDE.
- link.exe Win32 command line version.
- lnkr.exe DOS real mode version (obsolete).
Optimizing Linker Performance
For fast execution of the linker, follow these guidelines.
- Disable relocation checks by using the
/NORELOCATIONCHECK option.
- If the /MAP option is being used to create a .map file,
disable sorting of the map by using the /MAP:address
option.
- If the /MAP option is being used to create a .map file,
disable placement of line number information in the map
by using the /NOLINENUMBERS option (the default).
- If the executable file is a Windows program, use the /RC
option to add resources to the executable file.
- If running OPTLINK from a Windows DOS box,
use the DPMI version (link.exe) and set the DOS box
.pif file parameters in dosprmpt.pif as follows:
XMS required: 0XMS memory not locked (-1 desired)
EMS required: 0EMS memory not locked (-1 desired)
- Configure a small RAM disk so more EMS, XMS, or DPMI
memory is available for OPTLINK.
- Avoid linking to a network server.
Operational Modes
OPTLINK can get commands from the command line, interactively,
or from an indirect file.
All input on the command line should be in a series of parameters.
For the interactive mode at a console, use link.exe. Using indirect
file operation, you can enter prompt-like responses into a file. The
specific file name is passed to OPTLINK on the command line and
is read by OPTLINK for its linker input.
In all modes of operation, OPTLINK commands, switches and parameters
are the same.
Command Line and Interactive Operation
Command line operation of OPTLINK uses the following syntax:
LINK obj[,out[,map[,lib[,def[,res]]]]]
For interactive operation input LINK followed by any option
switches (described later) and press Enter. OPTLINK then
prompts for responses. Option switches may be entered after
any response.
OPTLINK parameters include the following:
- obj
- One or more input (.obj) file names.
If multiple names are
supplied, they may be joined by "+" characters or blank spaces, but
the comma separates the four parts of the command line. If more
names are required than are able to fit onto the command line, a "+"
immediately before the end of the line makes the list continue to the
next line.
Wild-card characters "?" and "*" to specify multiple files are
allowed. If
specific names are preceded or followed by wild-card references,
those modules specifically named will not be included twice. At the
end of the input list, use specific data or a "+" character to
invoke the default choices. If neither is supplied, operation switches
to the interactive mode, and OPTLINK prompts for the remaining
inputs. The "#" character tells OPTLINK to ignore the rest of the
comment characters following on that line.
- out
- Specifies the name for the output executable or dynamic link library.
If no extension is supplied, an .exe file is generated; if the
extension is .com, a .com file is created automatically, and if
extension is .sys, a binary device driver format file is created. To
skip this entry and cause OPTLINK to default to the executable type
provided in a definition file or option switch, supply a comma or
press the Enter key in the interactive mode. If no directive or option
switch is supplied, the default file name (that of the first .obj file)
with .exe extension will be created.
- map
- The file name for map output.
Using an Enter key while in the
interactive mode suppresses all map output, unless previously
configured with a /MAP suggested file name. See the related switch
descriptions (/MAP, /XREF, /LINENUMBERS, or /DETAILEDMAP)
later in this manual.
- lib
- Searches in order one or more library names to resolve any symbols
not defined in the input .obj files.
Wild card references can be used as with the obj entry.
The libraries are searched
in the order specified here. Use the "+" character
to separate multiple libraries.
Use the "+" continuation
character that comes before the end-of-line or before the comment
(#) string to extend past the end of the line.
The lib entry may be either a single file name or a pathname (with
trailing "\") to a directory containing the libraries.
OPTLINK searches library files in the order that they are presented to
it: that is, those named on the command line, and then those
referenced by embedded commands in object modules.
To locate each library file for which no path is specified, OPTLINK
first searches the current directory followed by any paths specified in
the LIB variable, and finally any paths named in the command line.
- def
- The module definition file name.
Optionally supplied, this file contains
program linking information.
- res
- One or more resource (.RES) file names.
When supplied, OPTLINK
performs the bind step of the Resource Compiler while linking. This
eliminates the need to use a Resource Compiler to combine
resources to the output file.
Also like the .OBJ entry, wild-card references may be used. The
libraries will be searched in the order specified. The same separators
used for the obj portion apply, and the res entry may also be
extended past the end of a line by means of the continuance
character (+) immediately before the end of line or comment (#)
string.
Examples of command line operation
The simplest method of using OPTLINK is to provide only the name
of the .obj file to be used and accept the default suggestions for all
other parameters:
C> LINK DUMP;
OPTLINK Copyright (C) Digital Mars 1989-94
All rights reserved.
OPTLINK's sign-on copyright message is displayed on the console as
shown above.
If the .obj file does not exist in the current directory or in any of
the paths supplied by the environment variables, OPTLINK sends an
error message:
C> LINK DUMPER;
OPTLINK Copyright (C) Digital Mars 1989-94
All rights reserved.
DUMPER.OBJ
Error 2: File Not Found DUMPER.OBJ
If there is not a semicolon on a short command line, OPTLINK
reverts to the interactive mode after all command line input is used,
as the following examples indicate:
C> LINK DUMP,,MYMAP;
OPTLINK Copyright (C) Digital Mars 1989-94
All rights reserved.
C> LINK DUMP,,MYMAP
OPTLINK Copyright (C) Digital Mars 1989-94
All rights reserved.
Libraries and Paths: (.lib):
Definition File: (.def):
Resource Files: (.res)
Examples of interactive operation
Use the Enter key at the Map File: prompt.
C> LINK
OPTLINK Copyright (C) Digital Mars 1989-94
All rights reserved.
OBJ Files: (.obj): curset
Output File: (curset.exe):
Map File: (.map):
Libraries and Paths: (.lib):
Definition File: (.def):
Resource Files: (.res)
Using the "+" and the "#" comment characters causes multiple
responses at the OBJ Files: prompt:
C> LINK
OPTLINK Copyright (C) Digital Mars 1989-94
All rights reserved.
OBJ Files: (.obj): file1+ # this is the first object file
OBJ Files: (.obj): file2+
OBJ Files: (.obj): file3 # this is the last
Output File: (file1.exe): myfile
Map File: (.map):
Libraries and Paths: (.lib): mylib
Definition File: (.def):
Resource Files: (.res)
Or use multiple file names on the same line:
C> LINK
OPTLINK Copyright (C) Digital Mars 1989-94
All rights reserved. OBJ Files: (.obj): file1 file2 file3
Output File: (file1.exe): myfile
Map File: (.map):
Libraries and Paths: (.lib): mylib
Definition File: (.def):
Resource Files: (.res)
Indirect File Operation
For more file names or option switches than
the command line can hold, use indirect file operation to
effectively eliminate any limit on the amount of information
supplied to OPTLINK. For most complicated applications, this is the
best choice.
OPTLINK uses the following syntax for indirect file operation:
LINK @indirfile
where indirfile is the name of an indirect response file.
During interactive operation at
each prompt, the indirect response file has a number of text lines.
Example of indirect file operation
If the file lnklst contains the following lines:
DUMP
NEWEXE
MYMAP;
then the following command lines are equivalent except that line
length in an indirect file is unlimited, while DOS limits the command
line to a maximum of 125 characters.
LINK @LNKLST
LINK DUMP,NEWEXE,MYMAP;
It is legal to use combinations of indirect file operation and either
command line or interactive operation. OPTLINK accepts more than
one indirect file specification. There are only two constraints: the
indirect files that are combined must result in a valid sequence of
responses and cannot be nested more than 10 deep.
Note:
It is possible for a valid file name to actually begin
with the "@" character. To keep such a file from
being erroneously recognized by OPTLINK as an
indirect response file, enclose the entire name of
the file in quotation marks.
Command formats
All three methods of providing command input use exactly the same
format for input information.
File name usage
OPTLINK uses the same file-naming conventions as those supplied
by the host operating system.
If a file extension is supplied, it must be separated from the name by
a period. If none is supplied, OPTLINK assumes or creates a default
value as described below.
The file name may be preceded by a pathname, which may be either
absolute or relative and may include a drive specifier. If no path is
specified, OPTLINK searches only the current working directory for
the file or creates it in the current working directory. If a drive is
specified, but no path, only the current directory for the specified
drive is used.
Default file extensions
If the file extension is omitted from a file name, OPTLINK assumes
or creates a default extension for the file that is determined by the
command with which the file name is associated. For instance, the
default extensions for the file names supplied with the OBJ Files:
prompt is .obj and for the Map File: prompt is .map. The
defaults follow and are described later for each command that
assumes or creates one. To refer to a file that has no
extension and without using the default, add the
"." separator after the file name to tell OPTLINK not to supply an
extension.
- .def
- Module Definition File
- .exe
- Executable files created by OPTLINK
- .lib
- Library files
- .map
- Listing of addresses generated by OPTLINK
- .obj
- Object files (in OMF format)
- .cfg
- Configuration file for default OPTLINK settings
- .res
- Resource files
- none
- Indirect command file used by OPTLINK
Special file names
Since OPTLINK uses standard I/O for keyboard input and
screen output, device names can be used in place of file names and
you may redirect input and output. The device names are:
- AUX
- refers to an auxiliary device (usually the same as
COM1)
- CON
- refers to the console (keyboard input or display
output)
- PRN
- refers to the printer (usually the same as LPT1)
NUL a null (nonexistent) file; if given as an input name,
returns end-of-file; if given as an output name, no
output is generated
To redirect OPTLINK input and output from and to files, use the
standard redirection keys. For example, the following command
redirects OPTLINK output (including all prompts) to file link.log
instead of to the screen:
LINK UTILITY; >LINK.LOG
Copyright © 1995-2004 Digital Mars. All Rights Reserved.