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Text file src/runtime/memclr_arm.s

Documentation: runtime

     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	TEXT runtime·memclrNoHeapPointers(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

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