Assembly Language Primer For Hackers (Part 8) Unconditional Branching

Description: This is Part 8 of the "Assembly Language Primer for Hackers" video series. Please begin here, by watching Part 1, if you have not already done so. In this video we will look at how to alter the program execution flow using unconditional branching. We will look at how to use the JMP instruction to make an unconditional branching to a new location in the code segment and how to use the CALL statement in conjunction with RET to save the program execution state. We will demonstrate all the concepts using very simple code snippets to aid understanding. Please download UnconditionalBranching.s to try out the various exercises discussed in this video.

Code:

.data

    HelloWorld:
        .asciz "Hello World!"

    CallDemo:
        .asciz "Call works!"

.text

    .globl _start

    _start:
        nop  

        call CallMe
        # Write  HelloWorld

        movl $4, %eax
        movl $1, %ebx
        movl $HelloWorld, %ecx
        movl $12, %edx
        int $0x80



  
    ExitProgram:
        # Exit the program
        movl $1, %eax
        movl $10, %ebx
        int $0x80

    CallMe:
        movl $4, %eax
        movl $1, %ebx
        movl $CallDemo, %ecx
        movl $11, %edx
        int $0x80
        ret

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