tinyXP.asm

; a 97-byte PE (as small as possible), XP compatible

;Ange Albertini, BSD Licence, 2010-2013

%include 'consts.inc'

IMAGEBASE equ 400000h

org IMAGEBASE

DOS_HEADER:
.e_magic dw 'MZ'

align 4, db 0

istruc IMAGE_NT_HEADERS
    at IMAGE_NT_HEADERS.Signature, db 'PE',0,0
iend
istruc IMAGE_FILE_HEADER
    at IMAGE_FILE_HEADER.Machine, dw IMAGE_FILE_MACHINE_I386
    ; we need to make sure it's not some crazy value in the NumbersOfSections, and the TimeStamp will fit the entrypoint code
    at IMAGE_FILE_HEADER.TimeDateStamp

bits 32
EntryPoint:
    push 42
    pop eax
    ret

    at IMAGE_FILE_HEADER.Characteristics, dw IMAGE_FILE_EXECUTABLE_IMAGE | IMAGE_FILE_32BIT_MACHINE
iend

istruc TRUNC_OPTIONAL_HEADER32
    at TRUNC_OPTIONAL_HEADER32.Magic,                 dw IMAGE_NT_OPTIONAL_HDR32_MAGIC
    at TRUNC_OPTIONAL_HEADER32.AddressOfEntryPoint,   dd EntryPoint - IMAGEBASE
    at TRUNC_OPTIONAL_HEADER32.ImageBase,             dd IMAGEBASE
    at TRUNC_OPTIONAL_HEADER32.SectionAlignment,      dd 4       ; also sets e_lfanew
    at TRUNC_OPTIONAL_HEADER32.FileAlignment,         dd 4
    at TRUNC_OPTIONAL_HEADER32.MajorSubsystemVersion, dw 4
    at TRUNC_OPTIONAL_HEADER32.SizeOfImage,           dd 2eh     ; can't be smaller
    at TRUNC_OPTIONAL_HEADER32.SizeOfHeaders,         dd 2ch     ; not necessary on all XP versions
    at TRUNC_OPTIONAL_HEADER32.Subsystem,             db IMAGE_SUBSYSTEM_WINDOWS_GUI
iend