alloca.s

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· S 代码 · 共 18 行

# 	%W%	(ULTRIX)	%G%

# like alloc, but automatic
# automatic free in return

.globl	_alloca
_alloca:
	.word	0x0000
	subl2	4(ap),sp	# crude allocation
	movl	16(fp),r1	# pc
	movq	8(fp),ap	# new (old) ap and fp
	bicl2	$3,sp		# 4-byte align
	addl2	$7*4,sp		# reuse space of mscp
	movl	sp,r0		# return value
	jmp 	(r1)		# funny return