Initial Contribution

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