Using Libraries

Like in many other languages, importing or including libraries are also possible in ASM. We will include the as an example here. The required files can be found in the Resources section.

ASM Code

The following ASM code includes the library and uses the dump_regs function defined in it.


%include ""

segment .text
    global asm_main

    enter 0, 0
    pusha        ; push registers on stack

    dump_regs 0     ; print register contents (in hexadecimal)

    popa          ; get the registers back from the stack

    mov eax, 0    ; return 0 to the C programm


We first need to compile asm_io.asm and acquire asm_io.o here. Note that the -d ELF_TYPE tells the ASM code, that we are compiling for a Linux system. Read asm_io.asm for how to compile for other systems.

$ nasm -f elf -d ELF_TYPE asm_io.asm

Thenafter we can compile the executable with the following command:

$ nasm -f elf dumpregs.asm
$ gcc -m32 -o dumpregs driver.o dumpregs.o asm_io.o  


This program will show the registry contents on the console. Here is a sample output:

$ ./dumpregs
Register Dump # 0
EAX = 00000001 EBX = F7723000 ECX = FFD49F30 EDX = FFD49F54
ESI = 00000000 EDI = 00000000 EBP = FFD49EF8 ESP = FFD49ED8
EIP = 08048492 FLAGS = 0286       SF       PF  

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