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; vim: filetype=nasm
; Copyright (c) 2023 by Test_User/hax
[bits 64]
[section elf_header start=0]
ELF_HEADER_START:
db 0x7F, "E", "L", "F" ; first 4 bytes
db 0x01 ; 64-bit
db 0x01 ; little-endian
db 0x01 ; version indicator, currently must be 1
db 0x00 ; generic unix thing
db 0x00 ; idk what this is
times 16 - ($ - $$) db 0x00 ; padding
dw 0x0002 ; executable thing
dw 0x0003 ; x86_64
dd 0x00000001 ; version again
dd ram_start ; starting address
dd PROGRAM_HEADER_START ; where the program header is in the file
dd 0x00000000 ; no section header
dd 0x00000000 ; no flags
dw ELF_HEADER_SIZE ; needed
dw PROGRAM_HEADER_SIZE ; how large is each program header
dw 0x0001 ; number of program headers
dw 0x0000 ; no section size because no sections
dw 0x0000 ; no sections
dw 0x0000 ; no string header thing because no sections
ELF_HEADER_SIZE equ $ - ELF_HEADER_START
PROGRAM_HEADER_START:
dd 0x00000001 ; load this into memory
dd file_start ; offset in file
dd ram_start ; offset in virtual address
dd 0x00000000 ; physical location, doesn't really matter
dd EXECUTABLE_SECTION_SIZE ; size in file
dd EXECUTABLE_SECTION_SIZE ; size in ram
dd 0x00000007 ; read | execute | write, apparently possible
dd 0x00000000 ; no alignment required
PROGRAM_HEADER_SIZE equ $ - PROGRAM_HEADER_START
PROGRAM_HEADER_END:
file_start EQU $-$$
[section executable vstart=0x0000000000400000+file_start align=1]
ram_start:
mov eax, 4
mov ebx, 1
mov ecx, msg
mov edx, msg_len
int 0x80
mov eax, 1
xor ebx, ebx
int 0x80
msg: db "Hello, world!", 0x0A ; buffer to be written to
msg_len equ $ - msg
EXECUTABLE_SECTION_SIZE equ $ - ram_start
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