1// Copyright 2014 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5#include "textflag.h"
6
7// See memclrNoHeapPointers Go doc for important implementation constraints.
8
9// func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
10TEXT runtime·memclrNoHeapPointers(SB), NOSPLIT, $0-8
11	MOVL	ptr+0(FP), DI
12	MOVL	n+4(FP), BX
13	XORL	AX, AX
14
15tail:
16	TESTL	BX, BX
17	JEQ	_0
18	CMPL	BX, $2
19	JBE	_1or2
20	CMPL	BX, $4
21	JB	_3
22	JE	_4
23	CMPL	BX, $8
24	JBE	_5through8
25	CMPL	BX, $16
26	JBE	_9through16
27	MOVL	BX, CX
28	SHRL	$2, CX
29	REP
30	STOSL
31	ANDL	$3, BX
32	JNE	tail
33	RET
34
35_1or2:
36	MOVB	AX, (DI)
37	MOVB	AX, -1(DI)(BX*1)
38	RET
39_0:
40	RET
41_3:
42	MOVW	AX, (DI)
43	MOVB	AX, 2(DI)
44	RET
45_4:
46	// We need a separate case for 4 to make sure we clear pointers atomically.
47	MOVL	AX, (DI)
48	RET
49_5through8:
50	MOVL	AX, (DI)
51	MOVL	AX, -4(DI)(BX*1)
52	RET
53_9through16:
54	MOVL	AX, (DI)
55	MOVL	AX, 4(DI)
56	MOVL	AX, -8(DI)(BX*1)
57	MOVL	AX, -4(DI)(BX*1)
58	RET
59