1// Inferno's libkern/memset-arm.s
2// https://bitbucket.org/inferno-os/inferno-os/src/master/libkern/memset-arm.s
3//
4//         Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
5//         Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com).  All rights reserved.
6//         Portions Copyright 2009 The Go Authors. All rights reserved.
7//
8// Permission is hereby granted, free of charge, to any person obtaining a copy
9// of this software and associated documentation files (the "Software"), to deal
10// in the Software without restriction, including without limitation the rights
11// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12// copies of the Software, and to permit persons to whom the Software is
13// furnished to do so, subject to the following conditions:
14//
15// The above copyright notice and this permission notice shall be included in
16// all copies or substantial portions of the Software.
17//
18// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
21// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
24// THE SOFTWARE.
25
26#include "textflag.h"
27
28#define TO	R8
29#define TOE	R11
30#define N	R12
31#define TMP	R12				/* N and TMP don't overlap */
32
33// See memclrNoHeapPointers Go doc for important implementation constraints.
34
35// func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
36// Also called from assembly in sys_windows_arm.s without g (but using Go stack convention).
37TEXT runtime·memclrNoHeapPointers(SB),NOSPLIT,$0-8
38	MOVW	ptr+0(FP), TO
39	MOVW	n+4(FP), N
40	MOVW	$0, R0
41
42	ADD	N, TO, TOE	/* to end pointer */
43
44	CMP	$4, N		/* need at least 4 bytes to copy */
45	BLT	_1tail
46
47_4align:				/* align on 4 */
48	AND.S	$3, TO, TMP
49	BEQ	_4aligned
50
51	MOVBU.P	R0, 1(TO)		/* implicit write back */
52	B	_4align
53
54_4aligned:
55	SUB	$31, TOE, TMP	/* do 32-byte chunks if possible */
56	CMP	TMP, TO
57	BHS	_4tail
58
59	MOVW	R0, R1			/* replicate */
60	MOVW	R0, R2
61	MOVW	R0, R3
62	MOVW	R0, R4
63	MOVW	R0, R5
64	MOVW	R0, R6
65	MOVW	R0, R7
66
67_f32loop:
68	CMP	TMP, TO
69	BHS	_4tail
70
71	MOVM.IA.W [R0-R7], (TO)
72	B	_f32loop
73
74_4tail:
75	SUB	$3, TOE, TMP	/* do remaining words if possible */
76_4loop:
77	CMP	TMP, TO
78	BHS	_1tail
79
80	MOVW.P	R0, 4(TO)		/* implicit write back */
81	B	_4loop
82
83_1tail:
84	CMP	TO, TOE
85	BEQ	_return
86
87	MOVBU.P	R0, 1(TO)		/* implicit write back */
88	B	_1tail
89
90_return:
91	RET
92