diff options
Diffstat (limited to 'libc/arch-x86/string/strncmp.S')
| -rw-r--r-- | libc/arch-x86/string/strncmp.S | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/libc/arch-x86/string/strncmp.S b/libc/arch-x86/string/strncmp.S new file mode 100644 index 0000000..5aa88d7 --- /dev/null +++ b/libc/arch-x86/string/strncmp.S @@ -0,0 +1,113 @@ +/* $OpenBSD: strncmp.S,v 1.3 2005/08/07 11:30:38 espie Exp $ */ +/* + * Written by J.T. Conklin <jtc@netbsd.org>. + * Public domain. + */ + +#include <machine/asm.h> + +/* + * NOTE: I've unrolled the loop eight times: large enough to make a + * significant difference, and small enough not to totally trash the + * cache. + */ + +ENTRY(strncmp) + pushl %ebx + movl 8(%esp),%eax + movl 12(%esp),%ecx + movl 16(%esp),%edx + testl %edx,%edx + jmp L2 /* Jump into the loop! */ + + .align 2,0x90 +L1: incl %eax + incl %ecx + decl %edx +L2: jz L4 /* strings are equal */ + movb (%eax),%bl + testb %bl,%bl + jz L3 + cmpb %bl,(%ecx) + jne L3 + + incl %eax + incl %ecx + decl %edx + jz L4 + movb (%eax),%bl + testb %bl,%bl + jz L3 + cmpb %bl,(%ecx) + jne L3 + + incl %eax + incl %ecx + decl %edx + jz L4 + movb (%eax),%bl + testb %bl,%bl + jz L3 + cmpb %bl,(%ecx) + jne L3 + + incl %eax + incl %ecx + decl %edx + jz L4 + movb (%eax),%bl + testb %bl,%bl + jz L3 + cmpb %bl,(%ecx) + jne L3 + + incl %eax + incl %ecx + decl %edx + jz L4 + movb (%eax),%bl + testb %bl,%bl + jz L3 + cmpb %bl,(%ecx) + jne L3 + + incl %eax + incl %ecx + decl %edx + jz L4 + movb (%eax),%bl + testb %bl,%bl + jz L3 + cmpb %bl,(%ecx) + jne L3 + + incl %eax + incl %ecx + decl %edx + jz L4 + movb (%eax),%bl + testb %bl,%bl + jz L3 + cmpb %bl,(%ecx) + jne L3 + + incl %eax + incl %ecx + decl %edx + jz L4 + movb (%eax),%bl + testb %bl,%bl + jz L3 + cmpb %bl,(%ecx) + je L1 + + .align 2,0x90 +L3: movzbl (%eax),%eax /* unsigned comparision */ + movzbl (%ecx),%ecx + subl %ecx,%eax + popl %ebx + ret + .align 2,0x90 +L4: xorl %eax,%eax + popl %ebx + ret |