1 /* ----------------------------------------------------------------------- * 2 * 3 * Copyright 2008 H. Peter Anvin - All Rights Reserved 4 * Copyright 2010 Intel Corporation; author: H. Peter Anvin 5 * 6 * Permission is hereby granted, free of charge, to any person 7 * obtaining a copy of this software and associated documentation 8 * files (the "Software"), to deal in the Software without 9 * restriction, including without limitation the rights to use, 10 * copy, modify, merge, publish, distribute, sublicense, and/or 11 * sell copies of the Software, and to permit persons to whom 12 * the Software is furnished to do so, subject to the following 13 * conditions: 14 * 15 * The above copyright notice and this permission notice shall 16 * be included in all copies or substantial portions of the Software. 17 * 18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 19 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES 20 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 21 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT 22 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 23 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 24 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 25 * OTHER DEALINGS IN THE SOFTWARE. 26 * 27 * ----------------------------------------------------------------------- */ 28 29 /* 30 * memmove.S 31 * 32 * Reasonably efficient memmove, using aligned transfers at least 33 * for the destination operand. 34 */ 35 36 .globl memmove 37 .type memmove,@function 38 .text 39 memmove: 40 movl 0xc(%esp),%ecx 41 movl 0x8(%esp),%edx 42 movl 0x4(%esp),%eax 43 44 jecxz 4f 45 46 pushl %esi 47 pushl %edi 48 pushl %eax /* Return value */ 49 50 movl %eax,%edi 51 movl %edx,%esi 52 53 cmpl %edi,%esi 54 jb 2f 55 56 /* source >= dest, forwards move */ 57 58 /* Initial alignment */ 59 1: 60 movl %edi,%edx 61 shrl $1,%edx 62 jnc 11f 63 movsb 64 decl %ecx 65 11: 66 movb %cl,%al 67 cmpl $2,%ecx 68 jb 13f 69 70 shrl $1,%edx 71 jnc 12f 72 movsw 73 subl $2,%ecx 74 12: 75 /* Bulk transfer */ 76 movb %cl,%al 77 shrl $2,%ecx 78 rep; movsl 79 80 /* Final alignment */ 81 testb $2,%al 82 jz 14f 83 movsw 84 13: 85 14: 86 testb $1,%al 87 jz 15f 88 movsb 89 15: 90 /* Common exit stub */ 91 3: 92 popl %eax /* Return value */ 93 popl %edi 94 popl %esi 95 4: 96 ret 97 98 99 2: 100 /* source < dest, backwards move if overlap */ 101 leal -1(%ecx,%esi),%eax 102 cmpl %eax,%edi 103 ja 1b /* No overlap, after all... */ 104 105 std 106 leal -1(%ecx,%edi),%edi 107 movl %eax,%esi 108 109 /* Initial alignment */ 110 movl %edi,%edx 111 shrl $1,%edx 112 jc 21f 113 movsb 114 decl %ecx 115 21: 116 decl %esi 117 decl %edi 118 movb %cl,%al 119 cmpl $2,%ecx 120 jb 23f 121 shrl $1,%edx 122 jc 22f 123 movsw 124 subl $2,%ecx 125 22: 126 /* Bulk transfer */ 127 subl $2,%esi 128 subl $2,%edi 129 movb %cl,%al 130 shrl $2,%ecx 131 rep; movsl 132 133 /* Final alignment */ 134 addl $2,%esi 135 addl $2,%edi 136 testb $2,%al 137 jz 24f 138 movsw 139 23: 140 24: 141 incl %esi 142 incl %edi 143 testb $1,%al 144 jz 25f 145 movsb 146 25: 147 cld 148 jmp 3b 149 150 .size memmove, .-memmove 151
