diff options
Diffstat (limited to 'sys/lib/libkern/arch/amd64/strcmp.S')
| -rw-r--r-- | sys/lib/libkern/arch/amd64/strcmp.S | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/sys/lib/libkern/arch/amd64/strcmp.S b/sys/lib/libkern/arch/amd64/strcmp.S new file mode 100644 index 00000000000..559563666d4 --- /dev/null +++ b/sys/lib/libkern/arch/amd64/strcmp.S @@ -0,0 +1,88 @@ +/* + * Written by J.T. Conklin <jtc@netbsd.org>. + * Public domain. + * Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com> + */ + +#include <machine/asm.h> + +#if defined(LIBC_SCCS) + RCSID("$NetBSD: strcmp.S,v 1.1 2001/06/19 00:22:47 fvdl Exp $") +#endif + +/* + * 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(strcmp) + jmp L2 /* Jump into the loop. */ + +L1: incq %rdi + incq %rsi +L2: movb (%rdi),%cl + testb %cl,%cl /* null terminator */ + jz L3 + cmpb %cl,(%rsi) /* chars match */ + jne L3 + + incq %rdi + incq %rsi + movb (%rdi),%cl + testb %cl,%cl + jz L3 + cmpb %cl,(%rsi) + jne L3 + + incq %rdi + incq %rsi + movb (%rdi),%cl + testb %cl,%cl + jz L3 + cmpb %cl,(%rsi) + jne L3 + + incq %rdi + incq %rsi + movb (%rdi),%cl + testb %cl,%cl + jz L3 + cmpb %cl,(%rsi) + jne L3 + + incq %rdi + incq %rsi + movb (%rdi),%cl + testb %cl,%cl + jz L3 + cmpb %cl,(%rsi) + jne L3 + + incq %rdi + incq %rsi + movb (%rdi),%cl + testb %cl,%cl + jz L3 + cmpb %cl,(%rsi) + jne L3 + + incq %rdi + incq %rsi + movb (%rdi),%cl + testb %cl,%cl + jz L3 + cmpb %cl,(%rsi) + jne L3 + + incq %rdi + incq %rsi + movb (%rdi),%cl + testb %cl,%cl + jz L3 + cmpb %cl,(%rsi) + je L1 +L3: movzbl (%rdi),%eax /* unsigned comparison */ + movzbl (%rsi),%edx + subl %edx,%eax + ret |