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This is a roadmap for learning x86 assembly, using nasm on Linux. I will try to list the topics as I learn, sorting them from the most basic to most advanced, adding a series of small tasks and reference material for each topic.

As I complete each task/topic, a check mark (✓) will be added to the item and a pointer to the solution will be provided. All solutions are inside the tasks directory.

Roadmap

The Basics

  • ✓ Install the necessary tools (installation/)

    • ✓ Install nasm (nasm.md)

    • ✓ Install ld, gcc, hexdump, objdump (most Linux distros already come with this installed)

  • ✓ First program: the exit system call (first_prog/)

    • ✓ Write, assemble and run a program that "does nothing", and check the return value (build.md)

    • ✓ Try to exit with various exit codes (exit8.asm and exit256.asm)

  • ✓ Make a "hello world" program (hello.asm)

  • ✓ Call assembly functions from C (call_from_c)

    • ✓ Write an assembly program with a callable function that returns a 64-bit integer (ret_int64.asm)

    • ✓ Write a small C program that calls this assembly function and displays the result in decimal, hexadecimal and binary formats (caller.c)

    • ✓ Write a program with a function that returns a negative number (ret_neg.asm)

  • Registers (registers)

    • ✓ Register names and sizes (theory)

    • The mov instruction

    • ✓ Write a program that moves values between registers of different sizes (run)

    • The xchg instruction

  • ✓ Look into machine code (inspect_binary/howto.md)

    • ✓ Check out the machine code of a program with hexdump

    • ✓ Disassemble a program with objdump

  • ✓ Basic Arithmetic (arithmetic/run.md)

    • ✓ Make a program that sums two numbers (add.asm)

    • ✓ Make a program that subtracts two numbers (sub.asm)

    • ✓ Make a program that uses increment (inc.asm)

    • ✓ Make a program that uses decrement (dec.asm)

    • ✓ Make a program that uses unsigned integer multiplication (mul.asm)

    • ✓ Make a program that uses signed integer multiplication (imul.asm)

    • ✓ Make a program that obtains the negative of a number (neg.asm)

  • ✓ Labels and Unconditional Jumps (jump)

  • ✓ Flags, Comparisons and Conditional Jumps (flags/theory.md)

    • ✓ Write a program with a conditional jump (cond_jump.asm)

    • ✓ Write a program with a loop (loop.asm)

    • ✓ Write a program using the overflow flag (overflow.asm)

    • ✓ Write a program contrasting the above and below comparisons with the greater than and less than comparisons (above_below.asm)

  • Logical and Bitwise Operations (logical)

  • ✓ Data Types, Memory Addressing and the .data Section (data/run.md)

    • ✓ How memory works in Linux? (theory.md)

    • ✓ Write a program that uses the .data section (print_data.asm)

    • ✓ Write a program that uses different data types (types.asm)

    • ✓ Write a program that uses addressing with displacement (ret4bytes.asm)

    • ✓ Write a program using addressing with a base register, an index register and scale factor (ret_words.asm)

    • ✓ Write a program using the .bss section (bss.asm)

    • ✓ Write a program that uses a "global variable" from the .bss section (var_bss.asm)

    • ✓ Write a program that increments a "global variable" from the .bss section (inc_var.asm)

    • ✓ Write a program that manipulates an array (array.asm)

  • ✓ The Stack (stack/theory.md)

    • ✓ Write a program that uses push and pop (push_pop.asm)

    • ✓ Write a program that uses the stack pointer to allocate space and access elements on the stack (sp.asm and sp2.asm)

  • ✓ The call Instruction (call/theory.md)

    • ✓ Write a program that uses call (call.asm)

    • ✓ Write a program that calls a print function/subroutine (print_func.asm)

  • Calling External Functions

    • ✓ Write a program divided in two files using extern/global (uselib.asm and lib.asm)

    • ✓ Write a program divided into two .asm files using the include macro (includer.asm and include.asm)

    • Write a library with a function containing arguments, and call it from another asm file

    • Call a function from C

    • Write an assembly library function that takes arguments, and call it from C

    • Write an assembly program that calls a C function

    • ✓ Write an assembly program that calls a C library function (malloc.asm)

  • Using the Heap

    • Use C's malloc and free to allocate and free memory dynamically

  • Special mov instructions

    • Sign and Zero Extend mov and "size casting" directive

    • Conditional mov

  • ✓ Arithmetic 2

    • ✓ Write a program with division operations (idiv.asm)

    • ✓ Write a program that does proper signed divisions with sign extensions (sx.asm)

  • Manipulating Strings

  • Floating point arithmetic

  • NASM local labels

Challenges

  • Write a function that receives an integer and prints it

  • Write a function that receives an integer and returns a string with it