adding 64bit numbers

[onlycurious]

Hello,

I was wondering how you would add 64 bit numbers in MASM with adc. Can someone show me a few SIMPLE examples ( I am a beginner).

[GregL]

onlycurious,

Hello, and welcome. Here is an example:

Code Select Expand


.386
.MODEL FLAT,STDCALL
OPTION CASEMAP:NONE

INCLUDE windows.inc

INCLUDE kernel32.inc
INCLUDE user32.inc

INCLUDELIB kernel32.lib
INCLUDELIB user32.lib

.DATA

    QW1 QWORD 4294967296
    QW2 QWORD 2147483648
    QW3 QWORD 0

.CODE

start:

    ; Add QWORDs (QW1 + QW2 = QW3)
    mov eax, DWORD PTR [QW1+0]   ; Low DWORD of QW1
    mov edx, DWORD PTR [QW1+4]   ; High DWORD of QW1
   
    add eax, DWORD PTR [QW2+0]   ; Low DWORD of QW2
    adc edx, DWORD PTR [QW2+4]   ; High DWORD of QW2
   
    mov DWORD PTR [QW3+0], eax
    mov DWORD PTR [QW3+4], edx
   
   
    ; Subtract QWORDS (QW1 - QW2 = QW3)
    mov eax, DWORD PTR [QW1+0]   ; Low DWORD of QW1
    mov edx, DWORD PTR [QW1+4]   ; High DWORD of QW1

    sub eax, DWORD PTR [QW2+0]   ; Low DWORD of QW2
    sbb edx, DWORD PTR [QW2+4]   ; High DWORD of QW2
   
    mov DWORD PTR [QW3+0], eax
    mov DWORD PTR [QW3+4], edx
   
    INVOKE ExitProcess, 0
   
END start