potato

~/learn/asm » cat ~/bin/asm                                         erik@royall
#!/bin/bash
# Simple assemble/link script

if [ -z $1 ]; then
  echo "Usage: ./asm <asmMainFile> (no extension)"
  exit
fi

# Verify no extensions were entered

if [ ! -r "$1.asm" ]; then
  echo "Error, $1.asm not found"
  echo "Note, do not exter file extensions."
  exit
fi

# Compile, assemble and link

yasm -g dwarf2 -f elf64 $1.asm -l $1.lst
ld -g -o $1 $1.o

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~/learn/asm » cat ex.asm                                            erik@royall
; Simple example demonstrating basic program
; format and layout.

; ******************************************
; Some basic data declarations

section .data

; -----
; Define Constants

EXIT_SUCCESS  equ   0       ; Successful operation
SYS_exit      equ   60      ; call code for terminate

; -----
; Byte (8-bit) variable declarations

bVar1         db    17
bVar2         db    9
bResult       db    0

; -----
; Word (16-bit) variable declarations

wVar1         dw    17000
wVar2         dw    9000
wResult       dw    0

; -----
; Double-word (32-bit) variable declarations

dVar1         dd    17000000
dVar2         dd    9000000
dResult       dd    0

; -----
; Quad-word (64-bit variable declarations)

qVar1         dq    170000000
qVar2         dq    90000000
qResult       dq    0

; ******************************************
; Code Section

section.text
global _start
_start:

; Performs a series of very basic addition operations
; to demonstrate basic program format.

; -----
; Byte example
;   bResult = bVar1 + bVar2

  mov       al, byte [bVar1]
  add       al, byte [bVar2]
  mov       byte [bResult], al

  ; Word

  mov       ax, word [wVar1]
  add       ax, word [wVar2]
  mov       word [wResult], ax

  ; Double-word

  mov       eax, dword [dVar1]
  add       eax, dword [dVar2]
  mov       dword [dResult], eax

  ; Quad-word

  mov       rax, qword [qVar1]
  add       rax, qword [qVar2]
  mov       qword [qResult], rax

last:
  mov       rax, SYS_exit       ; Call code for exit
  mov       rdi, EXIT_SUCCESS   ; Exit program with success
  syscall

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~/learn/asm » ~/bin/asm ex