diff options
Diffstat (limited to 'sys/arch/amd64/stand/libsa/alloca.S')
| -rw-r--r-- | sys/arch/amd64/stand/libsa/alloca.S | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/sys/arch/amd64/stand/libsa/alloca.S b/sys/arch/amd64/stand/libsa/alloca.S new file mode 100644 index 00000000000..d8b4b241575 --- /dev/null +++ b/sys/arch/amd64/stand/libsa/alloca.S @@ -0,0 +1,54 @@ +/*- + * Copyright (c) 1990 The Regents of the University of California. + * All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * William Jolitz. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <machine/asm.h> + +#if defined(LIBC_SCCS) + .text + .asciz "$OpenBSD: alloca.S,v 1.1 2004/02/03 12:09:47 mickey Exp $" +#endif + +/* like alloc, but automatic free in return */ + +ENTRY(alloca) + popl %edx /* pop return addr */ + popl %eax /* pop amount to allocate */ + movl %esp,%ecx + addl $3,%eax /* round up to next word */ + andl $-4,%eax + subl %eax,%esp + movl %esp,%eax /* base of newly allocated space */ + pushl 8(%ecx) /* copy possible saved registers */ + pushl 4(%ecx) + pushl 0(%ecx) + pushl %eax /* dummy to pop at callsite */ + jmp *%edx /* "return" */ |