Assembly-Playground

A repo for random assembly stuff I write

uses linux x86_64 system calls

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hello_world.asm

mostly self describing... prints "Hello world"

testing/box.asm

prints a small box to the screen (done as an early step in learning looping

testing/dynamicBox.asm

• also prints a small box, but with some adjustments
  • now uses mmap syscall to create space in memory
  • then constructs the box in this memory space based on x and y values defined in the data section
  • prints the box from memory

done to learn how memory allocation works in assembly

never actually bothers to de-allocate the memory

testing/numberInput.asm

• reads a single digit from stdin, then prints it out a number of times equal to the digits value
• precursor to the more complex number conversion file tests
• also done to play around with stdin a bit

testing/multiDigitIntegerFromString.asm

converts a string defined in the data section into an integer value then prints the character # a number of times equal to the value of the integer

testing/multiDigitIntegerToString.asm

• the reverse of the above, converts a 64 bit integer into a string and prints it
• does not however use the data section... as I was also using it to experiment with using the stack for temporary variable storage

testing/userInput.asm

• contains two subroutines that read user input into a buffer provided by the caller
• read_string - reads characters until either a maximum length, or a newline. whichever comes first
• read_line - reads characters to the end of the line, discards anything beyond the buffer length
• Both will 0 terminate the string in the buffer

basically_stdio.asm

IO subroutines meant to allow easy IO without using the C standard libraries

• basically_printf

  Expects arguments in rdi, rsi, rdx, rcx, r8, r9 and any further on the stack ,currently supports %d for integers, %s for strings, and %n for newline