MOVL	new+12(FP), CX
	LOCK
	CMPXCHGL	CX, 0(BX)
	SETEQ	ret+16(FP)
	RET

// bool	·Cas64(uint64 *val, uint64 old, uint64 new)
// Atomically:
//	if(*val == old){
//		*val = new;
//		return 1;
//	} else {
//		return 0;
//	}
TEXT ·Cas64(SB), NOSPLIT, $0-25
	MOVQ	ptr+0(FP), BX
	MOVQ	old+8(FP), AX
	MOVQ	new+16(FP), CX
	LOCK
	CMPXCHGQ	CX, 0(BX)
	SETEQ	ret+24(FP)
	RET

	ADDQ	$8, DI
	SUBQ	$8, BX
	CMPQ	CX, DX
	JEQ	bigloop
	XORQ	AX, AX	// return 0
	RET

	// remaining 0-8 bytes
leftover:
	MOVQ	-8(SI)(BX*1), CX
	MOVQ	-8(DI)(BX*1), DX
	CMPQ	CX, DX
	SETEQ	AX
	RET

small:
	CMPQ	BX, $0
	JEQ	equal

	LEAQ	0(BX*8), CX
	NEGQ	CX

	CMPB	SI, $0xf8
	JA	si_high

	// load at SI won't cross a page boundary.
	MOVQ	(SI), SI
	JMP	si_finish

	MOVL	new_hi+16(FP), CX
	LOCK
	CMPXCHG8B	0(BP)
	SETEQ	ret+20(FP)
	RET

// bool Casp1(void **p, void *old, void *new)
// Atomically:
//	if(*p == old){
//		*p = new;
//		return 1;
//	}else
//		return 0;
TEXT ·Casp1(SB), NOSPLIT, $0-13
	MOVL	ptr+0(FP), BX
	MOVL	old+4(FP), AX
	MOVL	new+8(FP), CX
	LOCK
	CMPXCHGL	CX, 0(BX)
	SETEQ	ret+12(FP)
	RET