Using as

The GNU Assembler

January 1994

This file is a user guide to the GNU assembler as.

• 1 Overview
  • 1.1 Structure of this Manual
  • 1.2 The GNU Assembler
  • 1.3 Object File Formats
  • 1.4 Command Line
  • 1.5 Input Files
  • 1.6 Output (Object) File
  • 1.7 Error and Warning Messages
• 2 Command-Line Options
  • 2.1 Enable Listings: -a[cdhlns]
  • 2.2 -D
  • 2.3 Work Faster: -f
  • 2.4 .include search path: -I path
  • 2.5 Difference Tables: -K
  • 2.6 Include Local Labels: -L
  • 2.7 Assemble in MRI Compatibility Mode: -M
  • 2.8 Dependency tracking: --MD
  • 2.9 Name the Object File: -o
  • 2.10 Join Data and Text Sections: -R
  • 2.11 Display Assembly Statistics: --statistics
  • 2.12 Compatible output: --traditional-format
  • 2.13 Announce Version: -v
  • 2.14 Suppress Warnings: -W
  • 2.15 Generate Object File in Spite of Errors: -Z
• 3 Syntax
  • 3.1 Preprocessing
  • 3.2 Whitespace
  • 3.3 Comments
  • 3.4 Symbols
  • 3.5 Statements
  • 3.6 Constants
    • 3.6.1 Character Constants
      • 3.6.1.1 Strings
      • 3.6.1.2 Characters
    • 3.6.2 Number Constants
      • 3.6.2.1 Integers
      • 3.6.2.2 Bignums
      • 3.6.2.3 Flonums
• 4 Sections and Relocation
  • 4.1 Background
  • 4.2 Linker Sections
  • 4.3 Assembler Internal Sections
  • 4.4 Sub-Sections
  • 4.5 bss Section
• 5 Symbols
  • 5.1 Labels
  • 5.2 Giving Symbols Other Values
  • 5.3 Symbol Names
  • 5.4 The Special Dot Symbol
  • 5.5 Symbol Attributes
    • 5.5.1 Value
    • 5.5.2 Type
    • 5.5.3 Symbol Attributes: a.out
      • 5.5.3.1 Descriptor
      • 5.5.3.2 Other
    • 5.5.4 Symbol Attributes for COFF
      • 5.5.4.1 Primary Attributes
      • 5.5.4.2 Auxiliary Attributes
    • 5.5.5 Symbol Attributes for SOM
• 6 Expressions
  • 6.1 Empty Expressions
  • 6.2 Integer Expressions
    • 6.2.1 Arguments
    • 6.2.2 Operators
    • 6.2.3 Prefix Operator
    • 6.2.4 Infix Operators
• 7 Assembler Directives
  • 7.1 .abort
  • 7.2 .ABORT
  • 7.3 .align abs-expr, abs-expr, abs-expr
  • 7.4 .app-file string
  • 7.5 .ascii "string"...
  • 7.6 .asciz "string"...
  • 7.7 .balign[wl] abs-expr, abs-expr, abs-expr
  • 7.8 .byte expressions
  • 7.9 .comm symbol , length
  • 7.10 .data subsection
  • 7.11 .def name
  • 7.12 .desc symbol, abs-expression
  • 7.13 .dim
  • 7.14 .double flonums
  • 7.15 .eject
  • 7.16 .else
  • 7.17 .endef
  • 7.18 .endif
  • 7.19 .equ symbol, expression
  • 7.20 .equiv symbol, expression
  • 7.21 .err
  • 7.22 .extern
  • 7.23 .file string
  • 7.24 .fill repeat , size , value
  • 7.25 .float flonums
  • 7.26 .global symbol, .globl symbol
  • 7.27 .hword expressions
  • 7.28 .ident
  • 7.29 .if absolute expression
  • 7.30 .include "file"
  • 7.31 .int expressions
  • 7.32 .irp symbol,values...
  • 7.33 .irpc symbol,values...
  • 7.34 .lcomm symbol , length
  • 7.35 .lflags
  • 7.36 .line line-number
  • 7.37 .linkonce [type]
  • 7.38 .ln line-number
  • 7.39 .mri val
  • 7.40 .list
  • 7.41 .long expressions
  • 7.42 .macro
  • 7.43 .nolist
  • 7.44 .octa bignums
  • 7.45 .org new-lc , fill
  • 7.46 .p2align[wl] abs-expr, abs-expr, abs-expr
  • 7.47 .psize lines , columns
  • 7.48 .quad bignums
  • 7.49 .rept count
  • 7.50 .sbttl "subheading"
  • 7.51 .scl class
  • 7.52 .section name
  • 7.53 .set symbol, expression
  • 7.54 .short expressions
  • 7.55 .single flonums
  • 7.56 .size
  • 7.57 .sleb128 expressions
  • 7.58 .skip size , fill
  • 7.59 .space size , fill
  • 7.60 .stabd, .stabn, .stabs
  • 7.61 .string "str"
  • 7.62 .symver
  • 7.63 .tag structname
  • 7.64 .text subsection
  • 7.65 .title "heading"
  • 7.66 .type int
  • 7.67 .val addr
  • 7.68 .uleb128 expressions
  • 7.69 .word expressions
  • 7.70 Deprecated Directives
• 8 Machine Dependent Features
• 9 ARC Dependent Features
  • 9.1 Options
  • 9.2 Floating Point
  • 9.3 ARC Machine Directives
• 10 AMD 29K Dependent Features
  • 10.1 Options
  • 10.2 Syntax
    • 10.2.1 Macros
    • 10.2.2 Special Characters
    • 10.2.3 Register Names
  • 10.3 Floating Point
  • 10.4 AMD 29K Machine Directives
  • 10.5 Opcodes
• 11 ARM Dependent Features
  • 11.1 Options
  • 11.2 Syntax
    • 11.2.1 Special Characters
    • 11.2.2 Register Names
  • 11.3 Floating Point
  • 11.4 ARM Machine Directives
  • 11.5 Opcodes
• 12 D10V Dependent Features
  • 12.1 D10V Options
  • 12.2 Syntax
    • 12.2.1 Size Modifiers
    • 12.2.2 Sub-Instructions
    • 12.2.3 Special Characters
    • 12.2.4 Register Names
    • 12.2.5 Addressing Modes
    • 12.2.6 @WORD Modifier
  • 12.3 Floating Point
  • 12.4 Opcodes
• 13 H8/300 Dependent Features
  • 13.1 Options
  • 13.2 Syntax
    • 13.2.1 Special Characters
    • 13.2.2 Register Names
    • 13.2.3 Addressing Modes
  • 13.3 Floating Point
  • 13.4 H8/300 Machine Directives
  • 13.5 Opcodes
• 14 H8/500 Dependent Features
  • 14.1 Options
  • 14.2 Syntax
    • 14.2.1 Special Characters
    • 14.2.2 Register Names
    • 14.2.3 Addressing Modes
  • 14.3 Floating Point
  • 14.4 H8/500 Machine Directives
  • 14.5 Opcodes
• 15 HPPA Dependent Features
  • 15.1 Notes
  • 15.2 Options
  • 15.3 Syntax
  • 15.4 Floating Point
  • 15.5 HPPA Assembler Directives
  • 15.6 Opcodes
• 16 80386 Dependent Features
  • 16.1 Options
  • 16.2 AT&T Syntax versus Intel Syntax
  • 16.3 Opcode Naming
  • 16.4 Register Naming
  • 16.5 Opcode Prefixes
  • 16.6 Memory References
  • 16.7 Handling of Jump Instructions
  • 16.8 Floating Point
  • 16.9 Writing 16-bit Code
  • 16.10 Notes
• 17 Intel 80960 Dependent Features
  • 17.1 i960 Command-line Options
  • 17.2 Floating Point
  • 17.3 i960 Machine Directives
  • 17.4 i960 Opcodes
    • 17.4.1 callj
    • 17.4.2 Compare-and-Branch
• 18 M680x0 Dependent Features
  • 18.1 M680x0 Options
  • 18.2 Syntax
  • 18.3 Motorola Syntax
  • 18.4 Floating Point
  • 18.5 680x0 Machine Directives
  • 18.6 Opcodes
    • 18.6.1 Branch Improvement
    • 18.6.2 Special Characters
• 19 MIPS Dependent Features
  • 19.1 Assembler options
  • 19.2 MIPS ECOFF object code
  • 19.3 Directives for debugging information
  • 19.4 Directives to override the ISA level
  • 19.5 Directives for extending MIPS 16 bit instructions
  • 19.6 Directive to mark data as an instruction
  • 19.7 Directives to save and restore options
• 20 Hitachi SH Dependent Features
  • 20.1 Options
  • 20.2 Syntax
    • 20.2.1 Special Characters
    • 20.2.2 Register Names
    • 20.2.3 Addressing Modes
  • 20.3 Floating Point
  • 20.4 SH Machine Directives
  • 20.5 Opcodes
• 21 SPARC Dependent Features
  • 21.1 Options
  • 21.2 Enforcing aligned data
  • 21.3 Floating Point
  • 21.4 Sparc Machine Directives
• 22 Z8000 Dependent Features
  • 22.1 Options
  • 22.2 Syntax
    • 22.2.1 Special Characters
    • 22.2.2 Register Names
    • 22.2.3 Addressing Modes
  • 22.3 Assembler Directives for the Z8000
  • 22.4 Opcodes
• 23 VAX Dependent Features
  • 23.1 VAX Command-Line Options
  • 23.2 VAX Floating Point
  • 23.3 Vax Machine Directives
  • 23.4 VAX Opcodes
  • 23.5 VAX Branch Improvement
  • 23.6 VAX Operands
  • 23.7 Not Supported on VAX
• 24 v850 Dependent Features
  • 24.1 Options
  • 24.2 Syntax
    • 24.2.1 Special Characters
    • 24.2.2 Register Names
  • 24.3 Floating Point
  • 24.4 V850 Machine Directives
  • 24.5 Opcodes
• 25 Reporting Bugs
  • 25.1 Have you found a bug?
  • 25.2 How to report bugs
• 26 Acknowledgements
• Index

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