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