An x86_64 OS X port of the cpuid example found in Ch. 4 of Professional Assembly

cpuid.s

# cpuid.s
# An x86_64 OS X port of the cpuid example found in Ch. 4 of Professional Assembly Language
#
# $ as -o cpuid.o cpuid.s
# $ ld -o cpuid cpuid.o
# $ ./cpuid 
# GenuineIntel
# $

.data
output:
	.asciz "\0\0\0\0\0\0\0\0\0\0\0\0\n"
len:
	.long len - output

.text
.globl start

start:
	xor %rax, %rax
	cpuid

	leaq output(%rip), %rsi
	movl %ebx, (%esi)
	movl %edx, 4(%esi)
	movl %ecx, 8(%esi)

	movq len(%rip), %rdx
	# leaq output(%rip), %rsi	# %rsi already contains address of output
	movq $0x1, %rdi				# STDOUT
	movq $0x02000004, %rax		# write
	syscall

	movq $0x0, %rdi
	movq $0x02000001, %rax		# exit
	syscall