Assembler

hello_asm.s

# hello_asm.s
# as hello_asm.s -o hello_asm.o
# ld hello_asm.o -e _main -o hello_asm -macosx_version_min 10.6 -lSystem

.section __DATA,__data
str:
	.asciz "Hello world!\n"

.section __TEXT,__text
.globl _main
_main:

	# src, dest
	# 4 = syswrite => %eax register
	# here, %eax = what to call
	# this is the opcode
	movl $0x2000004, %eax

	# 1 = stdout => %edi register
	# here, %edi = where to call/first arg? ish?
	movl $1, %edi

	# afaik, rsi, rdx, etc are registers for our variables?

	# GOT references the Global Offset Table
	#	aka, where the string above is stored.
	# %rip = instruction pointer (accesses the GOT)
	#	aka, grab the value at that spot
	#	and put it into %rsi
	movq str@GOTPCREL(%rip), %rsi

	# the length of the value to print -- 100? apparently
	#	and put it into %rdx
	movq $100, %rdx

	# and make the call
	# this calls whatever is in %eax, I think
	syscall


	# === finish up ===
	# put 0 in as our exit code/return value
	movl $0, %edi

	# and exit (opcode 1 => exit)
	movl $0x2000001, %eax
	syscall