Intel XENIX 286 Programmers Guide (86) - Tenox.tc

CHAPTER 7
as: ASSEMBLER
This chapter describes the usage and input syntax of the XENIX 8086/286 assembler, as.
The assembler produces relocatable object files from 8086/286 assembly language
source files. Object files contain relocation information and a complete symbol table
and may be linked to other object files using the XENIX link editor 1d.
as is designed to be used in those rare cases where C programs do not satisfy a
programming requirement. Thus, you can combine as object files with object files
produced by the XENIX C compiler, cc, to make complete programs. Note that the
output format of as has been designed so that if a file contains no unresolved references
to external symbols, it is executable without further processing.
This chapter does not teach assembly language programming, nor does it give a detailed
description of 8086/286 operation codes.
Command Usage
as is invoked as follows:
as [ option ]... filename ...
where each option is an assembler option and filename is the name of the assembler
source file. If the file name does not have the extension ".s", as displays a warning
message before assembling the file. Although as has a large nu mber of options, the
most commonly used are the -1 and -o options.
The -1 option causes the assembler to create an assembly listing that includes the
source, the assembled (binary) code, and any assembly errors. The listing file is named
filename.L.
The -o option causes the output to be placed in a given file. The option has the form
-o outfile
where outfile is the name of the file to receive the assembled program. If you do not
use the -o option, as copies the output to filename.o in the current directory.
For a complete description of all assembler options, see as in Appendix B, "Programming
Commands."
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