4 replies to this topic

[JMC31337]

A simple string input/output using NASM. I decided to post this simple yet effective ASM code. Comments have been added
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SIMPLE ASM (String Input)

[BITS 16] ;16 BIT MODE
[ORG 100h] ; START .COM FILE 100h
[SECTION .text] ;CODE

mov dx,msg                                 ;move "msg" --> data register
mov ah,9h                                   ;call display 
int 21h                                       ;DO IT!!

mov ah,0Ah                               ;call keyboard buffered input
mov dx,buffer               ;move buffer of 5 chars to data register
int 21h                                           ;DO IT!!!

mov ah,9h                                      ;call display
mov dx,crlf                        ;move carriage return+line feed
int 21h                                                   ;DO IT!!!

mov ah,9h                                          ;call display
mov dx,buffer+2           ;mov buffer + 2 offset index --> data register 
int 21h                                              ;DO IT!!!

mov ax,4C00h                                 ;call EXIT 
int 21h                                        ;DO IT!!!

[SECTION .data]                             ;SIMPLE DATA
msg db "Enter Password:",'$'
buffer db 5                                ;SETUP Buffer of 5 chars - NULL
db 0 
times 5 db 0 ;0 out buffer
db '$'                                                    ;estb NULL
crlf 10,13,"$"                            ;10/13 = carriage return line feed

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CODED BY: JMC31337

Edited by WingedPanther, 12 February 2009 - 06:39 PM.
add cod

[Brandon W]

Wow, I don't think I want to learn Assembly just yet. Maybe not ever, it looks so complex. Also, may I suggest using the [code] tags?

Also are the ";" the comments?

[WingedPanther]

I may not have added to code tags correctly. ASM is one of those things that is not that bad once you learn it, but it's non-trivial. One of these things I'll be picking up one I get back into Knuth's books again.

[John]

I just did something very similar using the ARM architecture earlier today. Except I only read/output a character.

[JMC31337]

yea ASM is def complicated...but once you get the basics of what the BIOS/DOS does you start to see patterns.. i.e... int 21h calls whatever Interrupt... but from i can see is its the proper utilization of segment registers... for instance when to use DX and AX CX .... if you want a good book on getting started i recommend Assembly Language Programming for DOS and Linux... if i have time i'll show stack usage with push n pop calls...