diff options
Diffstat (limited to 'sys/lib/libkern/arch/i386/bzero.S')
| -rw-r--r-- | sys/lib/libkern/arch/i386/bzero.S | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/sys/lib/libkern/arch/i386/bzero.S b/sys/lib/libkern/arch/i386/bzero.S new file mode 100644 index 00000000000..64a96c519bb --- /dev/null +++ b/sys/lib/libkern/arch/i386/bzero.S @@ -0,0 +1,46 @@ +/* + * Written by J.T. Conklin <jtc@netbsd.org>. + * Public domain. + */ + +#include <machine/asm.h> + +#if defined(LIBC_SCCS) + RCSID("$NetBSD: bzero.S,v 1.5 1995/10/07 09:27:02 mycroft Exp $") +#endif + +ENTRY(bzero) + pushl %edi + movl 8(%esp),%edi + movl 12(%esp),%edx + + cld /* set fill direction forward */ + xorl %eax,%eax /* set fill data to 0 */ + + /* + * if the string is too short, it's really not worth the overhead + * of aligning to word boundries, etc. So we jump to a plain + * unaligned set. + */ + cmpl $16,%edx + jb L1 + + movl %edi,%ecx /* compute misalignment */ + negl %ecx + andl $3,%ecx + subl %ecx,%edx + rep /* zero until word aligned */ + stosb + + movl %edx,%ecx /* zero by words */ + shrl $2,%ecx + andl $3,%edx + rep + stosl + +L1: movl %edx,%ecx /* zero remainder by bytes */ + rep + stosb + + popl %edi + ret |