1// Inferno's libkern/memset-arm.s
2// https://bitbucket.org/inferno-os/inferno-os/src/default/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// func memclrNoHeapPointers(ptr unsafe.Pointer, n uintptr)
34TEXT runtime·memclrNoHeapPointers(SB),NOSPLIT,$0-8
35	MOVW	ptr+0(FP), TO
36	MOVW	n+4(FP), N
37	MOVW	$0, R0
38
39	ADD	N, TO, TOE	/* to end pointer */
40
41	CMP	$4, N		/* need at least 4 bytes to copy */
42	BLT	_1tail
43
44_4align:				/* align on 4 */
45	AND.S	$3, TO, TMP
46	BEQ	_4aligned
47
48	MOVBU.P	R0, 1(TO)		/* implicit write back */
49	B	_4align
50
51_4aligned:
52	SUB	$31, TOE, TMP	/* do 32-byte chunks if possible */
53	CMP	TMP, TO
54	BHS	_4tail
55
56	MOVW	R0, R1			/* replicate */
57	MOVW	R0, R2
58	MOVW	R0, R3
59	MOVW	R0, R4
60	MOVW	R0, R5
61	MOVW	R0, R6
62	MOVW	R0, R7
63
64_f32loop:
65	CMP	TMP, TO
66	BHS	_4tail
67
68	MOVM.IA.W [R0-R7], (TO)
69	B	_f32loop
70
71_4tail:
72	SUB	$3, TOE, TMP	/* do remaining words if possible */
73_4loop:
74	CMP	TMP, TO
75	BHS	_1tail
76
77	MOVW.P	R0, 4(TO)		/* implicit write back */
78	B	_4loop
79
80_1tail:
81	CMP	TO, TOE
82	BEQ	_return
83
84	MOVBU.P	R0, 1(TO)		/* implicit write back */
85	B	_1tail
86
87_return:
88	RET
89