github.com/primecitizens/pcz/std@v0.2.1/core/mem/move_plan9_386.s (about) 1 // SPDX-License-Identifier: Apache-2.0 2 // Copyright 2023 The Prime Citizens 3 // 4 // Inferno's libkern/memmove-386.s 5 // https://bitbucket.org/inferno-os/inferno-os/src/master/libkern/memmove-386.s 6 // 7 // Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved. 8 // Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved. 9 // Portions Copyright 2009 The Go Authors. All rights reserved. 10 // 11 // Permission is hereby granted, free of charge, to any person obtaining a copy 12 // of this software and associated documentation files (the "Software"), to deal 13 // in the Software without restriction, including without limitation the rights 14 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 15 // copies of the Software, and to permit persons to whom the Software is 16 // furnished to do so, subject to the following conditions: 17 // 18 // The above copyright notice and this permission notice shall be included in 19 // all copies or substantial portions of the Software. 20 // 21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 22 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 23 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 24 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 25 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 26 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 27 // THE SOFTWARE. 28 29 //go:build pcz && 386 && plan9 30 31 #include "textflag.h" 32 33 // See memmove Go doc for important implementation constraints. 34 35 // func Move(to, from unsafe.Pointer, n uintptr) 36 TEXT ·Move(SB), NOSPLIT, $0-12 37 MOVL to+0(FP), DI 38 MOVL from+4(FP), SI 39 MOVL n+8(FP), BX 40 41 // REP instructions have a high startup cost, so we handle small sizes 42 // with some straightline code. The REP MOVSL instruction is really fast 43 // for large sizes. The cutover is approximately 1K. 44 tail: 45 TESTL BX, BX 46 JEQ move_0 47 CMPL BX, $2 48 JBE move_1or2 49 CMPL BX, $4 50 JB move_3 51 JE move_4 52 CMPL BX, $8 53 JBE move_5through8 54 CMPL BX, $16 55 JBE move_9through16 56 57 /* 58 * check and set for backwards 59 */ 60 CMPL SI, DI 61 JLS back 62 63 /* 64 * forward copy loop 65 */ 66 forward: 67 MOVL BX, CX 68 SHRL $2, CX 69 ANDL $3, BX 70 71 REP; MOVSL 72 JMP tail 73 /* 74 * check overlap 75 */ 76 back: 77 MOVL SI, CX 78 ADDL BX, CX 79 CMPL CX, DI 80 JLS forward 81 /* 82 * whole thing backwards has 83 * adjusted addresses 84 */ 85 86 ADDL BX, DI 87 ADDL BX, SI 88 STD 89 90 /* 91 * copy 92 */ 93 MOVL BX, CX 94 SHRL $2, CX 95 ANDL $3, BX 96 97 SUBL $4, DI 98 SUBL $4, SI 99 REP; MOVSL 100 101 CLD 102 ADDL $4, DI 103 ADDL $4, SI 104 SUBL BX, DI 105 SUBL BX, SI 106 JMP tail 107 108 move_1or2: 109 MOVB (SI), AX 110 MOVB -1(SI)(BX*1), CX 111 MOVB AX, (DI) 112 MOVB CX, -1(DI)(BX*1) 113 RET 114 move_0: 115 RET 116 move_3: 117 MOVW (SI), AX 118 MOVB 2(SI), CX 119 MOVW AX, (DI) 120 MOVB CX, 2(DI) 121 RET 122 move_4: 123 // We need a separate case for 4 to make sure we write pointers atomically. 124 MOVL (SI), AX 125 MOVL AX, (DI) 126 RET 127 move_5through8: 128 MOVL (SI), AX 129 MOVL -4(SI)(BX*1), CX 130 MOVL AX, (DI) 131 MOVL CX, -4(DI)(BX*1) 132 RET 133 move_9through16: 134 MOVL (SI), AX 135 MOVL 4(SI), CX 136 MOVL -8(SI)(BX*1), DX 137 MOVL -4(SI)(BX*1), BP 138 MOVL AX, (DI) 139 MOVL CX, 4(DI) 140 MOVL DX, -8(DI)(BX*1) 141 MOVL BP, -4(DI)(BX*1) 142 RET