ASM: Convert int to string in Assembly

This post shows how to convert int (DWORD) to string using MASM library dwtoa. There seems to be a bug in dwtoa as it can only handle 2147483647 instead of 4294967295 which is the maximum size of DWORD (32-bit). The code for dwtoa checks for a negative number which is not needed for DWORD. Note that DWORD is defined as 32-bit unsigned.

	.386
	.model flat, stdcall
	option casemap :none
	include \masm32\include\windows.inc
	include \masm32\include\kernel32.inc
	include \masm32\include\masm32.inc
	includelib \masm32\lib\kernel32.lib
	includelib \masm32\lib\masm32.lib
	.data
	buffer DB 11 DUP(0)
	;value DWORD 4294967295
	value DWORD 2147483647
	.code
	start:
	invoke dwtoa, value, addr buffer
	invoke StdOut, addr buffer
	invoke ExitProcess, 0
	end start

view raw int2string.asm hosted with ❤ by GitHub

Pre-requisite:

• Install MASM

To assemble:

\masm32\bin\ml /c /Zd /coff int2string.asm

To link:

\masm32\bin\Link /SUBSYSTEM:CONSOLE int2string.obj