'\" t
.\"     Title: ndisasm
.\"    Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 12/21/2022
.\"    Manual: The Netwide Assembler Project
.\"    Source: NASM
.\"  Language: English
.\"
.TH "NDISASM" "1" "12/21/2022" "NASM" "The Netwide Assembler Project"
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.SH "NAME"
ndisasm \- the Netwide Disassembler, an 80x86 binary file disassembler
.SH "SYNOPSIS"
.sp
\fBndisasm\fR [ \fB\-o\fR origin ] [ \fB\-s\fR sync\-point [\&...]] [ \fB\-a\fR | \fB\-i\fR ] [ \fB\-b\fR bits ] [ \fB\-u\fR ] [ \fB\-e\fR hdrlen ] [ \fB\-p\fR vendor ] [ \fB\-k\fR offset,length [\&...]] infile
.SH "DESCRIPTION"
.sp
The \fBndisasm\fR command generates a disassembly listing of the binary file infile and directs it to stdout\&.
.SH "OPTIONS"
.PP
\fB\-h\fR
.RS 4
Causes
\fBndisasm\fR
to exit immediately, after giving a summary of its invocation options\&.
.RE
.PP
\fB\-r\fR|\fB\-v\fR
.RS 4
Causes
\fBndisasm\fR
to exit immediately, after displaying its version number\&.
.RE
.PP
\fB\-o\fR \fIorigin\fR
.RS 4
Specifies the notional load address for the file\&. This option causes
\fBndisasm\fR
to get the addresses it lists down the left hand margin, and the target addresses of PC\-relative jumps and calls, right\&.
.RE
.PP
\fB\-s\fR \fIsync\-point\fR
.RS 4
Manually specifies a synchronisation address, such that
\fBndisasm\fR
will not output any machine instruction which encompasses bytes on both sides of the address\&. Hence the instruction which starts at that address will be correctly disassembled\&.
.RE
.PP
\fB\-e\fR \fIhdrlen\fR
.RS 4
Specifies a number of bytes to discard from the beginning of the file before starting disassembly\&. This does not count towards the calculation of the disassembly offset: the first
\fIdisassembled\fR
instruction will be shown starting at the given load address\&.
.RE
.PP
\fB\-k\fR \fIoffset,length\fR
.RS 4
Specifies that
\fIlength\fR
bytes, starting from disassembly offset
\fIoffset\fR, should be skipped over without generating any output\&. The skipped bytes still count towards the calculation of the disassembly offset\&.
.RE
.PP
\fB\-a\fR|\fB\-i\fR
.RS 4
Enables automatic (or intelligent) sync mode, in which
\fBndisasm\fR
will attempt to guess where synchronisation should be performed, by means of examining the target addresses of the relative jumps and calls it disassembles\&.
.RE
.PP
\fB\-b\fR \fIbits\fR
.RS 4
Specifies 16\-, 32\- or 64\-bit mode\&. The default is 16\-bit mode\&.
.RE
.PP
\fB\-u\fR
.RS 4
Specifies 32\-bit mode, more compactly than using \(oq\-b 32\(cq\&.
.RE
.PP
\fB\-p\fR \fIvendor\fR
.RS 4
Prefers instructions as defined by
\fIvendor\fR
in case of a conflict\&. Known
\fIvendor\fR
names include
\fBintel\fR,
\fBamd\fR,
\fBcyrix\fR, and
\fBidt\fR\&. The default is
\fBintel\fR\&.
.RE
.SH "RESTRICTIONS"
.sp
\fBndisasm\fR only disassembles binary files: it has no understanding of the header information present in object or executable files\&. If you want to disassemble an object file, you should probably be using \fBobjdump\fR(1)\&.
.sp
Auto\-sync mode won\(cqt necessarily cure all your synchronisation problems: a sync marker can only be placed automatically if a jump or call instruction is found to refer to it \fIbefore\fR \fBndisasm\fR actually disassembles that part of the code\&. Also, if spurious jumps or calls result from disassembling non\-machine\-code data, sync markers may get placed in strange places\&. Feel free to turn auto\-sync off and go back to doing it manually if necessary\&.
.SH "SEE ALSO"
.sp
\fBobjdump\fR(1)