table of contents
NASM(1) | The Netwide Assembler Project | NASM(1) |
NAME¶
nasm - the Netwide Assembler, a portable 80x86 assemblerSYNOPSIS¶
nasm [-@ response file] [-f format] [-o outfile] [-l listfile] [options...] filenameDESCRIPTION¶
The nasm command assembles the file filename and directs output to the file outfile if specified. If outfile is not specified, nasm will derive a default output file name from the name of its input file, usually by appending ‘.o’ or ‘.obj’, or by removing all extensions for a raw binary file. Failing that, the output file name will be ‘nasm.out’.OPTIONS¶
-@ filenameCauses nasm to process options from filename as if
they were included on the command line.
-a
Causes nasm to assemble the given input file
without first applying the macro preprocessor.
-D|-d macro[=value]
Pre-defines a single-line macro.
-E|-e
Causes nasm to preprocess the given input file,
and write the output to stdout (or the specified output file name), and
not actually assemble anything.
-f format
Specifies the output file format. To see a list of valid
output formats, use the -hf option.
-F format
Specifies the debug information format. To see a list of
valid output formats, use the -y option (for example -felf
-y).
-g
Causes nasm to generate debug information in
selected format.
-h
Causes nasm to exit immediately, after giving a
summary of its invocation options.
-hf
Same as -h , but also lists all valid output
formats.
-I|-i directory
Adds a directory to the search path for include files.
The directory specification must include the trailing slash, as it will be
directly prepended to the name of the include file.
-l listfile
Causes an assembly listing to be directed to the given
file, in which the original source is displayed on the right hand side (plus
the source for included files and the expansions of multi-line macros) and the
generated code is shown in hex on the left.
-M
Causes nasm to output Makefile-style dependencies
to stdout; normal output is suppressed.
-MG file
Same as -M but assumes that missing Makefile
dependecies are generated and added to dependency list without a prefix.
-MF file
Output Makefile-style dependencies to the specified
file.
-MD file
Same as a combination of -M and -MF
options.
-MT file
Override the default name of the dependency target
dependency target name. This is normally the same as the output filename,
specified by the -o option.
-MQ file
The same as -MT except it tries to quote
characters that have special meaning in Makefile syntax. This is not
foolproof, as not all characters with special meaning are quotable in
Make.
-MP
Emit phony target.
-O number
Optimize branch offsets.
-o outfile
•-O0: No optimization
•-O1: Minimal optimization
•-Ox: Multipass optimization
(default)
Specifies a precise name for the output file, overriding
nasm's default means of determining it.
-P|-p file
Specifies a file to be pre-included, before the main
source file starts to be processed.
-s
Causes nasm to send its error messages and/or help
text to stdout instead of stderr.
-t
Causes nasm to assemble in SciTech TASM compatible
mode.
-U|-u macro
Undefines a single-line macro.
-v
Causes nasm to exit immediately, after displaying
its version number.
*-W[no-]foo'
Causes nasm to enable or disable certain classes
of warning messages, in gcc-like style, for example -Worphan-labels or
-Wno-orphan-labels.
-w[+-]foo
Causes nasm to enable or disable certain classes
of warning messages, for example -w+orphan-labels or
-w-macro-params.
-X format
Specifies error reporting format (gnu or vc).
-y
Causes nasm to list supported debug formats.
-Z filename
Causes nasm to redirect error messages to
filename. This option exists to support operating systems on which
stderr is not easily redirected.
--prefix, --postfix
Prepend or append (respectively) the given argument to
all global or extern variables.
SYNTAX¶
This man page does not fully describe the syntax of nasm's assembly language, but does give a summary of the differences from other assemblers. Registers have no leading ‘%’ sign, unlike gas, and floating-point stack registers are referred to as st0, st1, and so on. Floating-point instructions may use either the single-operand form or the double. A TO keyword is provided; thus, one could either writefadd st0,st1 fadd st1,st0
fadd st1 fadd to st1
message: times 3 db 'abc' times 64-$+message db 0
mov ax,wordvar
mov ax,[wordvar] mov ax,[wordvar+1] mov ax,[es:wordvar+bx]
mov ax,es:wordvar[bx] es mov ax,wordvar[1]
DIRECTIVES¶
SECTION name or SEGMENT name causes nasm to direct all following code to the named section. Section names vary with output file format, although most formats support the names .text, .data and .bss. (The exception is the obj format, in which all segments are user-definable.) ABSOLUTE address causes nasm to position its notional assembly point at an absolute address: so no code or data may be generated, but you can use RESB, RESW and RESD to move the assembly point further on, and you can define labels. So this directive may be used to define data structures. When you have finished doing absolute assembly, you must issue another SECTION directive to return to normal assembly. BITS 16, BITS 32 or BITS 64 switches the default processor mode for which nasm is generating code: it is equivalent to USE16 or USE32 in DOS assemblers. EXTERN symbol and GLOBAL symbol import and export symbol definitions, respectively, from and to other modules. Note that the GLOBAL directive must appear before the definition of the symbol it refers to. STRUC strucname and ENDSTRUC, when used to bracket a number of RESB, RESW or similar instructions, define a data structure. In addition to defining the offsets of the structure members, the construct also defines a symbol for the size of the structure, which is simply the structure name with size tacked on to the end.FORMAT-SPECIFIC DIRECTIVES¶
ORG address is used by the bin flat-form binary output format, and specifies the address at which the output code will eventually be loaded. GROUP grpname seg1 seg2... is used by the obj (Microsoft 16-bit) output format, and defines segment groups. This format also uses UPPERCASE, which directs that all segment, group and symbol names output to the object file should be in uppercase. Note that the actual assembly is still case sensitive. LIBRARY libname is used by the rdf output format, and causes a dependency record to be written to the output file which indicates that the program requires a certain library in order to run.MACRO PREPROCESSOR¶
Single-line macros are defined using the %define or %idefine commands, in a similar fashion to the C preprocessor. They can be overloaded with respect to number of parameters, although defining a macro with no parameters prevents the definition of any macro with the same name taking parameters, and vice versa. %define defines macros whose names match case-sensitively, whereas %idefine defines case-insensitive macros. Multi-line macros are defined using %macro and %imacro (the distinction is the same as that between %define and %idefine), whose syntax is as follows%macro name minprm[-maxprm][+][.nolist] [defaults] <some lines of macro expansion text> %endmacro
BUGS¶
Please report bugs through the bug tracker function at http://nasm.us.SEE ALSO¶
as(1), ld(1).05/21/2014 | NASM |