I looked in the Pcasm book and could not find the movsx or movzx command. However I found this ...

Archive:  nasm-0.98.39-xdoc.zip
  Length      Date    Time    Name
---------  ---------- -----   ----
   565153  01/15/2005 16:21   doc/nasmdoc.txt
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   565153                     1 file
    

B.4.181 `MOVSX', `MOVZX': Move Data with Sign or Zero Extend

MOVSX reg16,r/m8 ; o16 0F BE /r [386]
MOVSX reg32,r/m8 ; o32 0F BE /r [386]
MOVSX reg32,r/m16 ; o32 0F BF /r [386]

MOVZX reg16,r/m8 ; o16 0F B6 /r [386]
MOVZX reg32,r/m8 ; o32 0F B6 /r [386]
MOVZX reg32,r/m16 ; o32 0F B7 /r [386]

`MOVSX' sign-extends its source (second) operand to the length of
its destination (first) operand, and copies the result into the
destination operand. `MOVZX' does the same, but zero-extends rather
than sign-extending.

Yeah, too bad x64dbg is so stupidly bloated compared to OllyDbg. I mean, orders of magnitude more bloated... (but OllyDbg 64 seems to be dead, sigh)

The code I posted above from the fasm sources will print to the console without printf. It uses GetStdHandle and WriteFile. So you can too.

And your code for the looping example pushes ebx each time around the loop. But no associated pops are present. You will overflow the stack if you do that too many times.

And note that the dec instruction also sets the Z flag so you don't need the following cmp.

7
6
5
4
3
2
1
0
Enter your name:
    

7
Enter your name:
    

*ptr++ = blah;    

*(--esp) = blah; // same as "push blah"    

// pop blah
blah = *esp;
esp++;    

Show your full (modified) code? The cmp is indeed useless but you probably messed up something else.

format PE console
entry main
include 'macro/import32.inc'

section '.data' data readable writeable
msg3 db "%d",1010b,0
msg db "Enter your name: ",0

section '.code' code readable executable

main:
mov ebx, 8
loop_1:
                dec ebx
                push ebx
                push msg3
                call [printf]; Still using printf. Have not figured out the other one.
                ;cmp ebx, 0
                jnz loop_1
push msg
call [printf]
pop ebx
mov dword [esp],0
push 0
call [exit]

section '.idata' import data readable
library msvcrt,'msvcrt.dll'

import msvcrt,\
printf,'printf',\
exit,'exit'
    

7
Enter your name: 
    

What is the assembly equivalent of printf?

C0deHer3tic wrote:

What is the assembly equivalent of printf?

Funny question for assembly programmers. I will try to keep it philosophic. Printf is an equivalent of maybe a few hundred or more assembly instructions in a special composition.

Assembly instruction is the smallest part of any task. If you read a book, than the whole book can be imagined as an application while the chapters are functions inside the application and words may be treated as c-functions while the letters contained of any word are assembly instructions building the c-function.

This doesn't print out the numbers as it goes. It just does:

Code:

7
Enter your name: 
    

I am new to assembly, and therefore I have no idea where to start. I tried to start off like learning C, however I see that I needed to know other things before that. I am a noob to all of this, so my questions will seem ridiculous I am sure.

Best start would be tutorials in the internet for assembly programming x86.

A more easy step is to program WIN applications using the WIN functions, which can be called simply using register values and pointers and using data structures. I think this is the fastest way keeping motivation while showing fast success of your work.

Try out the Hello World example and then get deeper step-by-step. There are many examples provided with FASM as well which can be compiled fast and investigated after in detail.

MENU
--------
1. Add
2. Sub
etc...
    

void lines(int amount)
{
    int i;
    for(i=0;i!=amount;i++)
         printf("\n");
    return;
}
...........
So in the code I could do this

printf("Hello World!");
lines(2);
    

; Adds two numbers and prints results 
;------------------------------------------------

format PE console
entry main

;IMPORTS
;------------------------------------------------
include 'win32a.inc'
section '.idata' import data readable
library kernel32, "kernel32.dll", \
                msvcrt, "msvcrt.dll"

import kernel32, \
         ExitProcess, "ExitProcess"

import msvcrt, \
         printf, "printf", \
         scanf, "scanf"
;------------------------------------------------

;DATA
;------------------------------------------------
section 'data' data readable writeable
prompt1         db              "Please enter a number:",9h,0
prompt2         db              "Enter next number:",9h,0

result          db              "The number %d added to %d = %d",0
newline db              "",1010b,0

input           db              "%d",0

num1            dd              ?
num2            dd              ?

;-------------------------------------------------

;[Main Program]
;------------------------------------------------
section '.code' code executable

;[PROGRAM START]
;------------------------------------------------
main:

;[Prints Prompt1 to console]
;------------------------------------------------
                push    prompt1
                call    [printf]
;------------------------------------------------

;[Get input]
;------------------------------------------------
                push    num1
                push    input
                call    [scanf]
;------------------------------------------------

;[Newline]
;------------------------------------------------       
                push    newline
                call    [printf]
;------------------------------------------------

;[Prints Prompt2 to console]
;------------------------------------------------
                push    prompt2
                call    [printf]
;------------------------------------------------

;[Get input2]
;------------------------------------------------
                push    num2
                push    input
                call    [scanf]
;------------------------------------------------

;[result printed out]
;------------------------------------------------
                mov   ebx, dword[num1]
                add     ebx, dword[num2]
                push    ebx
                push    dword [num2]
                push    dword[num1]
                
                push    result
                call    [printf]
;------------------------------------------------

;[Clean up]
;------------------------------------------------
                add             esp, 4*4
                push    0
;------------------------------------------------

;[Kill program]
;------------------------------------------------
                call    [ExitProcess]
;------------------------------------------------
    

Why would I want to learn programming for code that doesn't even run in my environment? If there is a good reason, I am open to hear it.