Difference between revisions of "CSC231 Copying Strings in RAM"
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(→Copying msg1 into msg2, 1 byte at a time) |
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=Copying msg1 into msg2, 1 byte at a time= | =Copying msg1 into msg2, 1 byte at a time= | ||
| − | + | (Remember, we don't know loops yet!) | |
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<source lang="asm"> | <source lang="asm"> | ||
Revision as of 08:14, 19 September 2012
--D. Thiebaut 09:08, 19 September 2012 (EDT)
A Program with 2 Strings
;;; movString1s.asm
;;; D. Thiebaut
;;;
;;;
;;;
;;; To assemble, link, and run:
;;; nasm -f elf -F stabs movString1s.asm
;;; ld -melf_i386 -o movStrings1 movStrings1.o
;;; ./movStrings1
;;;
section .data
msg1 db "Smith College", 10
msg1Len equ $-msg1
msg2 db ".............", 10
section .text
global _start
_start:
;;; print msg1
mov eax, 4
mov ebx, 1
mov ecx, msg1
mov edx, msg1Len
int 0x80
;;; print msg2
mov eax, 4
mov ebx, 1
mov ecx, msg2
mov edx, msg1Len
int 0x80
;;; exit
mov ebx, 0
mov eax, 1
int 0x80
Copying msg1 into msg2, 1 byte at a time
(Remember, we don't know loops yet!)
;;; movString1s.asm
;;; D. Thiebaut
;;;
;;; This version copies msg1 to msg2
;;;
;;; To assemble, link, and run:
;;; nasm -f elf -F stabs movString1s.asm
;;; ld -melf_i386 -o movStrings2 movStrings2.o
;;; ./movStrings2
;;;
section .data
msg1 db "Smith College", 10
msg1Len equ $-msg1
msg2 db ".............", 10
section .text
global _start
_start:
;;; print msg1
mov eax, 4
mov ebx, 1
mov ecx, msg1
mov edx, msg1Len
int 0x80
;;; print original msg2
mov eax, 4
mov ebx, 1
mov ecx, msg2
mov edx, msg1Len
int 0x80
;;; copy msg1 into msg2
mov al, byte [msg1]
mov byte[msg2], al
mov al, byte [msg1+1]
mov byte[msg2+1], al
mov al, byte [msg1+2]
mov byte[msg2+2], al
mov al, byte [msg1+3]
mov byte[msg2+3], al
mov al, byte [msg1+4]
mov byte[msg2+4], al
mov al, byte [msg1+5]
mov byte[msg2+5], al
mov al, byte [msg1+6]
mov byte[msg2+6], al
mov al, byte [msg1+7]
mov byte[msg2+7], al
mov al, byte [msg1+8]
mov byte[msg2+8], al
mov al, byte [msg1+9]
mov byte[msg2+9], al
mov al, byte [msg1+10]
mov byte[msg2+10], al
mov al, byte [msg1+11]
mov byte[msg2+11], al
mov al, byte [msg1+12]
mov byte[msg2+12], al
;;; print new msg2
mov eax, 4
mov ebx, 1
mov ecx, msg2
mov edx, msg1Len
int 0x80
;;; exit
mov ebx, 0
mov eax, 1
int 0x80
