diff options
| -rw-r--r-- | exit-code.asm | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/exit-code.asm b/exit-code.asm new file mode 100644 index 0000000..05a8965 --- /dev/null +++ b/exit-code.asm @@ -0,0 +1,99 @@ +; fasmg quine.asm quine + +macro mov.d target, source + match =rax?, target + db 0x48, 0xC7, 0xC0 +; 48 eAX REX.W prefix +; (DEC is the 32-bit meaning, ignore it) +; eAX -> register identifier, +; width depends on operand +; REX.W -> set 64-bit operand mode +; c7 Grp 11^1A - MOV Ev, Iz +; immediate to register +; 1A -> bits 5,4,3 of ModR/M are opcode +; extension +; E -> modR/M byte to follow for operand +; v -> word of appropriate size +; I -> immediate data +; z -> 32-bit operand +; c0 ModR/M byte +; 0b11000000 +; 11 mod: always 11 +; 000 op/reg: Mov Ev, Iz +; 00x w absent +; 0 w (ignored) + dd source + else match =rdi, target + db 0x48, 0xC7, 0xC7 +; 7: 48 c7 c7 2a 00 00 00 mov $0x2a,%rdi +; 48 eAX REX.W prefix +; (DEC is the 32-bit meaning, ignore it) +; c7 Grp 11^1A - MOV Ev, Iz +; immediate to register +; 1A -> bits 5,4,3 of ModR/M are opcode +; extension +; Ev -> ModR/M to follow for 32-bit operand +; Iz -> Immediate data, 32-bits +; c7 ModR/M byte +; 0b11000111 +; 11 mod: always 11 +; 000 op/reg: Mov Ev, Iz +; 11x w present +; 1 w true; use EDI + dd source + end match +end macro + +macro syscall + db 0x0F, 0x05 +; 0f two-byte escape +; 05 syscall ^ o64 +end macro + + + + +org 0x08048000 + +elf_header: + db 0x7F, "ELF" + db 2 ; 64-bit + db 1 ; little-endian + db 1 ; ELF header format version 1 + db 0 ; System-V ABI + db 8 dup 0 ; (padding) + + dw 2 ; executable + dw 0x3E ; Intel x86-64 + dd 1 ; ELF format version + + dq _start ; entry point + dq program_header - $$ ; program header offset + dq 0 ; section header offset + dd 0 ; processor flags + dw elf_header_size + dw program_header_entry_size + dw 1 ; number of program header entries + dw 0 ; section header entry size + dw 0 ; number of section header entries + dw 0 ; section name string table index +elf_header_size = $ - elf_header + +program_header: + dd 1 ; "loadable" segment type + dd 0x05 ; read+execute permission + dq 0 ; offset in file + dq $$ ; virtual address + dq 0 ; (padding) + dq file_size ; size in file + dq file_size ; size in memory + dq 0 ; segment alignment +program_header_entry_size = $ - program_header + +_start: + mov.d rax, 60 + mov.d rdi, 42 + syscall + +file_size = $ - $$ + |