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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.
#include "../../cmd/ld/textflag.h"
// void runtime·memmove(void*, void*, uintptr)
TEXT runtime·memmove(SB), NOSPLIT, $0-24
MOVQ to+0(FP), DI
MOVQ fr+8(FP), SI
MOVQ n+16(FP), BX
// REP instructions have a high startup cost, so we handle small sizes
// with some straightline code. The REP MOVSQ instruction is really fast
// for large sizes. The cutover is approximately 1K. We implement up to
// 256 because that is the maximum SSE register load (loading all data
// into registers lets us ignore copy direction).
tail:
TESTQ BX, BX
JEQ move_0
CMPQ BX, $2
JBE move_1or2
CMPQ BX, $4
JBE move_3or4
CMPQ BX, $8
JBE move_5through8
CMPQ BX, $16
JBE move_9through16
CMPQ BX, $32
JBE move_17through32
CMPQ BX, $64
JBE move_33through64
CMPQ BX, $128
JBE move_65through128
CMPQ BX, $256
JBE move_129through256
// TODO: use branch table and BSR to make this just a single dispatch
/*
* check and set for backwards
*/
CMPQ SI, DI
JLS back
/*
* forward copy loop
*/
forward:
MOVQ BX, CX
SHRQ $3, CX
ANDQ $7, BX
REP; MOVSQ
JMP tail
back:
/*
* check overlap
*/
MOVQ SI, CX
ADDQ BX, CX
CMPQ CX, DI
JLS forward
/*
* whole thing backwards has
* adjusted addresses
*/
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
CLD
ADDQ $8, DI
ADDQ $8, SI
SUBQ BX, DI
SUBQ BX, SI
JMP tail
move_1or2:
MOVB (SI), AX
MOVB -1(SI)(BX*1), CX
MOVB AX, (DI)
MOVB CX, -1(DI)(BX*1)
move_0:
RET
move_3or4:
MOVW (SI), AX
MOVW -2(SI)(BX*1), CX
MOVW AX, (DI)
MOVW CX, -2(DI)(BX*1)
RET
move_5through8:
MOVL (SI), AX
MOVL -4(SI)(BX*1), CX
MOVL AX, (DI)
MOVL CX, -4(DI)(BX*1)
RET
move_9through16:
MOVQ (SI), AX
MOVQ -8(SI)(BX*1), CX
MOVQ AX, (DI)
MOVQ CX, -8(DI)(BX*1)
RET
move_17through32:
MOVOU (SI), X0
MOVOU -16(SI)(BX*1), X1
MOVOU X0, (DI)
MOVOU X1, -16(DI)(BX*1)
RET
move_33through64:
MOVOU (SI), X0
MOVOU 16(SI), X1
MOVOU -32(SI)(BX*1), X2
MOVOU -16(SI)(BX*1), X3
MOVOU X0, (DI)
MOVOU X1, 16(DI)
MOVOU X2, -32(DI)(BX*1)
MOVOU X3, -16(DI)(BX*1)
RET
move_65through128:
MOVOU (SI), X0
MOVOU 16(SI), X1
MOVOU 32(SI), X2
MOVOU 48(SI), X3
MOVOU -64(SI)(BX*1), X4
MOVOU -48(SI)(BX*1), X5
MOVOU -32(SI)(BX*1), X6
MOVOU -16(SI)(BX*1), X7
MOVOU X0, (DI)
MOVOU X1, 16(DI)
MOVOU X2, 32(DI)
MOVOU X3, 48(DI)
MOVOU X4, -64(DI)(BX*1)
MOVOU X5, -48(DI)(BX*1)
MOVOU X6, -32(DI)(BX*1)
MOVOU X7, -16(DI)(BX*1)
RET
move_129through256:
MOVOU (SI), X0
MOVOU 16(SI), X1
MOVOU 32(SI), X2
MOVOU 48(SI), X3
MOVOU 64(SI), X4
MOVOU 80(SI), X5
MOVOU 96(SI), X6
MOVOU 112(SI), X7
MOVOU -128(SI)(BX*1), X8
MOVOU -112(SI)(BX*1), X9
MOVOU -96(SI)(BX*1), X10
MOVOU -80(SI)(BX*1), X11
MOVOU -64(SI)(BX*1), X12
MOVOU -48(SI)(BX*1), X13
MOVOU -32(SI)(BX*1), X14
MOVOU -16(SI)(BX*1), X15
MOVOU X0, (DI)
MOVOU X1, 16(DI)
MOVOU X2, 32(DI)
MOVOU X3, 48(DI)
MOVOU X4, 64(DI)
MOVOU X5, 80(DI)
MOVOU X6, 96(DI)
MOVOU X7, 112(DI)
MOVOU X8, -128(DI)(BX*1)
MOVOU X9, -112(DI)(BX*1)
MOVOU X10, -96(DI)(BX*1)
MOVOU X11, -80(DI)(BX*1)
MOVOU X12, -64(DI)(BX*1)
MOVOU X13, -48(DI)(BX*1)
MOVOU X14, -32(DI)(BX*1)
MOVOU X15, -16(DI)(BX*1)
RET
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