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// Derived from Inferno's libkern/memmove-386.s (adapted for amd64)
// http://code.google.com/p/inferno-os/source/browse/libkern/memmove-386.s
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved.
// Portions Copyright 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
TEXT memmove(SB), 7, $0
MOVQ to+0(FP), DI
MOVQ fr+8(FP), SI
MOVLQSX n+16(FP), BX
CMPQ BX, $0
JLT fault
/*
* check and set for backwards
* should we look closer for overlap?
*/
CMPQ SI, DI
JLS back
/*
* forward copy loop
*/
MOVQ BX, CX
SHRQ $3, CX
ANDQ $7, BX
REP; MOVSQ
MOVQ BX, CX
REP; MOVSB
MOVQ to+0(FP),AX
RET
/*
* whole thing backwards has
* adjusted addresses
*/
back:
ADDQ BX, DI
ADDQ BX, SI
STD
/*
* copy
*/
MOVQ BX, CX
SHRQ $3, CX
ANDQ $7, BX
SUBQ $8, DI
SUBQ $8, SI
REP; MOVSQ
ADDQ $7, DI
ADDQ $7, SI
MOVQ BX, CX
REP; MOVSB
CLD
MOVQ to+0(FP),AX
RET
/*
* if called with negative count,
* treat as error rather than
* rotating all of memory
*/
fault:
MOVQ $0,SI
MOVQ 0(SI), AX
RET
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