Question

Write a program in NASM that turns a 32-bit numeric value (e.g., 0xFFFFh) and converts it to a byte array such that it can be printed to the screen using a system call method. A loop is necessary for converting the numeric value to ASCII for output. Again, use a system call (e.g., int 80h) to print the value to the console. Calling external functions (e.g. printf) is not allowed. You may use the starter file attached to this assignment.

Answer 1

The program is written below,

The program is written below,

.386

.MODEL FLAT, stdcall

.STACK 4096

GetStdHandle PROTO, nStdHandle:DWORD

WriteConsoleA PROTO,

hConsoleOutput:DWORD, ; output handle

lpBuffer:PTR BYTE, ; pointer to buffer

nNumberOfCharsToWrite:DWORD, ; size of buffer

lpNumberOfCharsWritten:PTR DWORD, ; num bytes written

lpReserved:DWORD ; not used (NULL)

ExitProcess PROTO, dwExitCode:DWORD

.data

bytesWritten DWORD 0 ; for WriteConsoleA

stdHandle DWORD 0 ; for WriteConsoleA

s1 BYTE "Hello Universe", 13, 10, 0

lenS1 = ($ - s1)

.code

_main PROC

print:

; get STDOUT handle

push -11 ; request STD_OUTPUT_HANDLE (-11)

call GetStdHandle ; call WinAPI to get console handle

mov stdHandle, eax ; save stdHandle

push 0 ; reserved, push NULL

push OFFSET bytesWritten ; bytes written

mov eax, lenS1

push eax ; bytes to write

push OFFSET s1 ; string address

push stdHandle ; STD_OUPUT_HANDLE

call WriteConsoleA ; call win api to write text to console

done:

INVOKE ExitProcess, 0

_main ENDP

END