setjmp.s

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

TEXT	setjmp(SB), 1, $-4
	MOVW	LR, R4
	MOVW	R1, (R3)
	MOVW	R4, 4(R3)
	MOVW	$0, R3
	RETURN

TEXT	longjmp(SB), 1, $-4
	MOVW	R3, R4
	MOVW	r+4(FP), R3
	CMP	R3, $0
	BNE	ok		/* ansi: "longjmp(0) => longjmp(1)" */
	MOVW	$1, R3		/* bless their pointed heads */
ok:	MOVW	(R4), R1
	MOVW	4(R4), R4
	MOVW	R4, LR
	BR	(LR)

/*
 * trampoline functions because the kernel smashes r1
 * in the uregs given to notejmp
 */
TEXT	__noterestore(SB), 1, $-4
	MOVW	R4, R3
	MOVW	R5, LR
	BR	(LR)