diff options
Diffstat (limited to 'contrib/syslinux-4.02/memdisk/memmove.S')
| -rw-r--r-- | contrib/syslinux-4.02/memdisk/memmove.S | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/memdisk/memmove.S b/contrib/syslinux-4.02/memdisk/memmove.S new file mode 100644 index 0000000..b7ac676 --- /dev/null +++ b/contrib/syslinux-4.02/memdisk/memmove.S @@ -0,0 +1,139 @@ +/* ----------------------------------------------------------------------- * + * + * Copyright 2008 H. Peter Anvin - 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. + * + * ----------------------------------------------------------------------- */ + +/* + * memmove.S + * + * Reasonably efficient memmove, using aligned transfers at least + * for the destination operand. + */ + + .globl memmove + .type memmove,@function + .text +memmove: + jecxz 3f + + pushl %esi + pushl %edi + pushl %eax /* Return value */ + + movl %eax,%edi + movl %edx,%esi + + cmpl %edi,%esi + jb 1f + + /* source >= dest, forwards move */ + + /* Initial alignment */ + movl %edi,%edx + shrl $1,%edx + jnc 11f + movsb + decl %ecx +11: + movb %cl,%al + cmpl $2,%ecx + jb 13f + + shrl $1,%edx + jnc 12f + movsw + subl $2,%ecx +12: + /* Bulk transfer */ + movb %cl,%al + shrl $2,%ecx + rep; movsl + + /* Final alignment */ + testb $2,%al + jz 14f + movsw +13: +14: + testb $1,%al + jz 15f + movsb +15: + jmp 2f + + +1: + /* source < dest, backwards move */ + std + leal -1(%ecx,%esi),%esi + leal -1(%ecx,%edi),%edi + + /* Initial alignment */ + movl %edi,%edx + shrl $1,%edx + jc 21f + movsb + decl %ecx +21: + decl %esi + decl %edi + movb %cl,%al + cmpl $2,%ecx + jb 23f + shrl $1,%edx + jc 22f + movsw + subl $2,%ecx +22: + /* Bulk transfer */ + subl $2,%esi + subl $2,%edi + movb %cl,%al + shrl $2,%ecx + rep; movsl + + /* Final alignment */ + addl $2,%esi + addl $2,%edi + testb $2,%al + jz 24f + movsw +23: +24: + incl %esi + incl %edi + testb $1,%al + jz 25f + movsb +25: + cld +2: + popl %eax /* Return value */ + popl %edi + popl %esi +3: + ret + + .size memmove, .-memmove |