Hey guys, I need to write a program based on the one below but I have no idea what it is doing or means, only 3 lectures into the course. Can someone who understands it make some notes next to each line for me explaining what's going on?

 

I don't know exactly what language it is but it's the one you write in DOS and then assemble and link, IBM PC i think its called? the module im studying is microprocessor programming.

 

Cheers

Yas

 

[Edit: for some reason the tabbed lines stay to the left so i'v replaced the tabs with a dash]

 

 

 

.186

 

code SEGMENT para 'CODE'

ASSUME CS:code,DS:code,ES:nothing,SS:nothing

 

putdec:

-MOV AX,5

-CALL PUTIT

-MOV AX,4C00H

-INT 21H

;

 

PUTIT:

-PUSH AX

-PUSH BX

-PUSH CX

-PUSH DX

-PUSH BP

-PUSH DS

-PUSHF

-MOV DX,CS

-MOV DS,DX

-MOV BYTE PTR sign,00

-TEST AX,08000

-JZ POS

-MOV BYTE PTR sign,01

 

POS:

-NEG AX

-MOV CX,0000

-MOV BX,000Ah ;........................................ 10

 

again1:

-MOV DX,0000

-DIV BX ; .................................................divide by ten

-ADD DL,30h

-PUSH DX

-INC CX

-CMP AX,+00

-JNZ again1

-CMP byte ptr sign,00

-JZ plonk

-MOV AL,2Dh

-PUSH AX

-INC CX

 

plonk:

-MOV DX,6

-SUB DX,CX

 

newch:

-POP dx ; .................................................pop character

-MOV AH,2

-INT 21h

-LOOP newch

-POPF

-POP DS

-POP BP

-POP DX

-POP CX

-POP BX

-POP AX

-RET

 

sign db 0

allign db 0

 

CODE ENDS

 

End

those push, pop and move sound like stack operations to me, sorry I couldn't be more help- its been 4 years since i was at uni and I didn't even pay any attention when I was there

OK, I'm rusty as hell but I think it's x86 assembly language. Loads of info here including a decent tutorial http://grail.cba.csuohio.edu/~somos/asmx86.html. Thing about assembly is it looks horrible but each operation is actually really simple so you shouldn't have too much trouble figuring it out. In short

 

PUSH - pushes an item onto the stack and moves the stack pointer accordingly (depends on size of item: 32-bits, 64-bits etc).

 

POP - does the reverse of push: pulls an item from the stack and moves the stack pointer back.

 

MOV - moves an value into/out of a register

 

SUB/ADD/DIV - (integer) arithmetic operations

 

INC - increment

 

Like I say, once you've got a basic understanding it should be fairly easy to figure it out.

thanks guys, will be having a good look at it today. anyone else done assembly language before?