auto import from //depot/cupcake/@135843

1 files changed, 63 insertions, 0 deletions

diff --git a/libc/arch-x86/string/strcpy.S b/libc/arch-x86/string/strcpy.S
new file mode 100644
index 0000000..341eb6c
--- /dev/null
+++ b/libc/arch-x86/string/strcpy.S
@@ -0,0 +1,63 @@
+/*	$OpenBSD: strcpy.S,v 1.8 2005/08/07 11:30:38 espie Exp $ */
+/*
+ * Written by J.T. Conklin <jtc@netbsd.org>.
+ * Public domain.
+ */
+
+#include <machine/asm.h>
+
+#if defined(APIWARN)
+#APP
+	.section .gnu.warning.strcpy
+	.ascii "warning: strcpy() is almost always misused, please use strlcpy()"
+#NO_APP
+#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(strcpy)
+	movl	4(%esp),%ecx		/* dst address */
+	movl	8(%esp),%edx		/* src address */
+	pushl	%ecx			/* push dst address */
+
+	.align 2,0x90
+L1:	movb	(%edx),%al		/* unroll loop, but not too much */
+	movb	%al,(%ecx)
+	testb	%al,%al
+	jz	L2
+	movb	1(%edx),%al
+	movb	%al,1(%ecx)
+	testb	%al,%al
+	jz	L2
+	movb	2(%edx),%al
+	movb	%al,2(%ecx)
+	testb	%al,%al
+	jz	L2
+	movb	3(%edx),%al
+	movb	%al,3(%ecx)
+	testb	%al,%al
+	jz	L2
+	movb	4(%edx),%al
+	movb	%al,4(%ecx)
+	testb	%al,%al
+	jz	L2
+	movb	5(%edx),%al
+	movb	%al,5(%ecx)
+	testb	%al,%al
+	jz	L2
+	movb	6(%edx),%al
+	movb	%al,6(%ecx)
+	testb	%al,%al
+	jz	L2
+	movb	7(%edx),%al
+	movb	%al,7(%ecx)
+	addl	$8,%edx
+	addl	$8,%ecx
+	testb	%al,%al
+	jnz	L1
+L2:	popl	%eax			/* pop dst address */
+	ret