/* ----------------------------------------------------------------------- * * * 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: movl 0xc(%esp),%ecx movl 0x8(%esp),%edx movl 0x4(%esp),%eax 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