58 lines
1.4 KiB
ArmAsm
58 lines
1.4 KiB
ArmAsm
;; Hello World Program #1
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;; Compile with: nasm -f elf hello.s
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;; Link with: ld -m elf_i386 -o hello hello.o
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;; Run with: ./hello
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;; sys/unistd_32.h
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%define SYS_write 4
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%define SYS_exit 1
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;; unistd.h
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%define STDOUT 1
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section .data
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msg db "Okay, so we're doing 32-bit subroutines now, huh?", 0Ah, 00h
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section .text
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global _start
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_start:
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mov ecx, msg ; Put the address of our message into eax.
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call strlen ; call the function strlen. We're using EAX as our argument.
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call printit
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call exit
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strlen:
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; will probably want its state restored correctly, right?
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mov edx, ecx
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strlen_next:
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cmp byte [edx], 0
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jz strlen_done
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inc edx
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jmp strlen_next
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strlen_done:
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sub edx, ecx ; Straight from the counted-hello file
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ret
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;; Takes EAX as the address of the message and EDX as the
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;; length, and prints them. Restores all used registers
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;; when finished. EDX contains the count.
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printit:
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push ebx
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push eax
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mov ebx, STDOUT
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mov eax, SYS_write
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int 80h
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pop eax
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pop ebx
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ret
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;; Since this terminates the program, I'm not worried about
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;; managing the stack correctly.
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exit:
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mov ebx, 0
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mov eax, SYS_exit
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int 80h
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