merge x86_64 optimized string support

1 files changed, 123 insertions, 0 deletions

diff --git a/libc/string/x86_64/strcspn.S b/libc/string/x86_64/strcspn.S
new file mode 100644
index 000000000..e1a22e4f1
--- /dev/null
+++ b/libc/string/x86_64/strcspn.S
@@ -0,0 +1,123 @@
+/* strcspn (str, ss) -- Return the length of the initial segment of STR
+			which contains no characters from SS.
+   For AMD x86-64.
+   Copyright (C) 1994-1997, 2000, 2002, 2003, 2004, 2005
+   Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>.
+   Bug fixes by Alan Modra <Alan@SPRI.Levels.UniSA.Edu.Au>.
+   Adopted for x86-64 by Andreas Jaeger <aj@suse.de>.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include "_glibc_inc.h"
+
+/* BEWARE: `#ifdef strcspn' means that strcspn is redefined as `strpbrk' */
+#define STRPBRK_P (defined strcspn)
+
+	.text
+ENTRY (strcspn)
+
+	movq %rdi, %rdx		/* Save SRC.  */
+
+	/* First we create a table with flags for all possible characters.
+	   For the ASCII (7bit/8bit) or ISO-8859-X character sets which are
+	   supported by the C string functions we have 256 characters.
+	   Before inserting marks for the stop characters we clear the whole
+	   table.  */
+	movq %rdi, %r8			/* Save value.  */
+	subq $256, %rsp			/* Make space for 256 bytes.  */
+	movl $32,  %ecx			/* 32*8 bytes = 256 bytes.  */
+	movq %rsp, %rdi
+	xorl %eax, %eax			/* We store 0s.  */
+	cld
+	rep
+	stosq
+
+	movq %rsi, %rax			/* Setup skipset.  */
+
+/* For understanding the following code remember that %rcx == 0 now.
+   Although all the following instruction only modify %cl we always
+   have a correct zero-extended 64-bit value in %rcx.  */
+
+	.p2align 4
+L(2):	movb (%rax), %cl	/* get byte from skipset */
+	testb %cl, %cl		/* is NUL char? */
+	jz L(1)			/* yes => start compare loop */
+	movb %cl, (%rsp,%rcx)	/* set corresponding byte in skipset table */
+
+	movb 1(%rax), %cl	/* get byte from skipset */
+	testb $0xff, %cl	/* is NUL char? */
+	jz L(1)			/* yes => start compare loop */
+	movb %cl, (%rsp,%rcx)	/* set corresponding byte in skipset table */
+
+	movb 2(%rax), %cl	/* get byte from skipset */
+	testb $0xff, %cl	/* is NUL char? */
+	jz L(1)			/* yes => start compare loop */
+	movb %cl, (%rsp,%rcx)	/* set corresponding byte in skipset table */
+
+	movb 3(%rax), %cl	/* get byte from skipset */
+	addq $4, %rax		/* increment skipset pointer */
+	movb %cl, (%rsp,%rcx)	/* set corresponding byte in skipset table */
+	testb $0xff, %cl	/* is NUL char? */
+	jnz L(2)		/* no => process next dword from skipset */
+
+L(1):	leaq -4(%rdx), %rax	/* prepare loop */
+
+	/* We use a neat trick for the following loop.  Normally we would
+	   have to test for two termination conditions
+	   1. a character in the skipset was found
+	   and
+	   2. the end of the string was found
+	   But as a sign that the character is in the skipset we store its
+	   value in the table.  But the value of NUL is NUL so the loop
+	   terminates for NUL in every case.  */
+
+	.p2align 4
+L(3):	addq $4, %rax		/* adjust pointer for full loop round */
+
+	movb (%rax), %cl	/* get byte from string */
+	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
+	je L(4)			/* yes => return */
+
+	movb 1(%rax), %cl	/* get byte from string */
+	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
+	je L(5)			/* yes => return */
+
+	movb 2(%rax), %cl	/* get byte from string */
+	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
+	jz L(6)			/* yes => return */
+
+	movb 3(%rax), %cl	/* get byte from string */
+	cmpb %cl, (%rsp,%rcx)	/* is it contained in skipset? */
+	jne L(3)		/* no => start loop again */
+
+	incq %rax		/* adjust pointer */
+L(6):	incq %rax
+L(5):	incq %rax
+
+L(4):	addq $256, %rsp		/* remove skipset */
+#if STRPBRK_P
+	xorl %edx,%edx
+	orb %cl, %cl		/* was last character NUL? */
+	cmovzq %rdx, %rax	/* Yes:	return NULL */
+#else	
+	subq %rdx, %rax		/* we have to return the number of valid
+				   characters, so compute distance to first
+				   non-valid character */
+#endif
+	ret
+END (strcspn)