| // 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. |
| 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 |
| |
| /* |
| * 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 |