diff options
Diffstat (limited to 'contrib/syslinux-4.02/memdisk/memset.S')
| -rw-r--r-- | contrib/syslinux-4.02/memdisk/memset.S | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/memdisk/memset.S b/contrib/syslinux-4.02/memdisk/memset.S new file mode 100644 index 0000000..e641415 --- /dev/null +++ b/contrib/syslinux-4.02/memdisk/memset.S @@ -0,0 +1,86 @@ +/* ----------------------------------------------------------------------- * + * + * 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. + * + * ----------------------------------------------------------------------- */ + +/* + * memset.S + * + * Reasonably efficient memset, using aligned transfers at least + * for the destination operand. + */ + + .globl memset + .type memset,@function + .text +memset: + jecxz 6f + + pushl %edi + pushl %ebx + pushl %eax /* Return value */ + + movl %eax,%edi + movb %dl,%dh + movzwl %dx,%eax + shll $16,%edx + orl %edx,%eax + + /* Initial alignment */ + movl %edi,%edx + shrl $1,%edx + jnc 1f + stosb + decl %ecx +1: + movb %cl,%bl + cmpl $2,%ecx + jb 3f + shrl $1,%edx + jnc 2f + stosw + subl $2,%ecx +2: + /* Bulk transfer */ + movb %cl,%bl + shrl $2,%ecx + rep; stosl + + testb $2,%bl + jz 4f + stosw +3: +4: + testb $1,%bl + jz 5f + stosb +5: + popl %eax /* Return value */ + popl %ebx + popl %edi +6: + ret + + .size memset, .-memset |