merge x86_64 optimized string support

1 files changed, 256 insertions, 0 deletions

diff --git a/libc/string/x86_64/strcat.S b/libc/string/x86_64/strcat.S
new file mode 100644
index 000000000..1106cb4ed
--- /dev/null
+++ b/libc/string/x86_64/strcat.S
@@ -0,0 +1,256 @@
+/* strcat(dest, src) -- Append SRC on the end of DEST.
+   Optimized for x86-64.
+   Copyright (C) 2002 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Andreas Jaeger <aj@suse.de>, 2002.
+
+   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"
+
+
+	.text
+ENTRY (BP_SYM (strcat))
+	movq %rdi, %rcx		/* Dest. register. */
+	andl $7, %ecx		/* mask alignment bits */
+	movq %rdi, %rax		/* Duplicate destination pointer.  */
+	movq $0xfefefefefefefeff,%r8
+
+	/* First step: Find end of destination.  */
+	jz 4f			/* aligned => start loop */
+
+	neg %ecx		/* We need to align to 8 bytes.  */
+	addl $8,%ecx
+	/* Search the first bytes directly.  */
+0:	cmpb $0x0,(%rax)	/* is byte NUL? */
+	je 2f			/* yes => start copy */
+	incq %rax		/* increment pointer */
+	decl %ecx
+	jnz 0b
+
+
+
+	/* Now the source is aligned.  Scan for NUL byte.  */
+	.p2align 4
+4:
+	/* First unroll.  */
+	movq (%rax), %rcx	/* get double word (= 8 bytes) in question */
+	addq $8,%rax		/* adjust pointer for next word */
+	movq %r8, %rdx		/* magic value */
+	addq %rcx, %rdx		/* add the magic value to the word.  We get
+				   carry bits reported for each byte which
+				   is *not* 0 */
+	jnc 3f			/* highest byte is NUL => return pointer */
+	xorq %rcx, %rdx		/* (word+magic)^word */
+	orq %r8, %rdx		/* set all non-carry bits */
+	incq %rdx		/* add 1: if one carry bit was *not* set
+				   the addition will not result in 0.  */
+	jnz 3f			/* found NUL => return pointer */
+
+	/* Second unroll.  */
+	movq (%rax), %rcx	/* get double word (= 8 bytes) in question */
+	addq $8,%rax		/* adjust pointer for next word */
+	movq %r8, %rdx		/* magic value */
+	addq %rcx, %rdx		/* add the magic value to the word.  We get
+				   carry bits reported for each byte which
+				   is *not* 0 */
+	jnc 3f			/* highest byte is NUL => return pointer */
+	xorq %rcx, %rdx		/* (word+magic)^word */
+	orq %r8, %rdx		/* set all non-carry bits */
+	incq %rdx		/* add 1: if one carry bit was *not* set
+				   the addition will not result in 0.  */
+	jnz 3f			/* found NUL => return pointer */
+
+	/* Third unroll.  */
+	movq (%rax), %rcx	/* get double word (= 8 bytes) in question */
+	addq $8,%rax		/* adjust pointer for next word */
+	movq %r8, %rdx		/* magic value */
+	addq %rcx, %rdx		/* add the magic value to the word.  We get
+				   carry bits reported for each byte which
+				   is *not* 0 */
+	jnc 3f			/* highest byte is NUL => return pointer */
+	xorq %rcx, %rdx		/* (word+magic)^word */
+	orq %r8, %rdx		/* set all non-carry bits */
+	incq %rdx		/* add 1: if one carry bit was *not* set
+				   the addition will not result in 0.  */
+	jnz 3f			/* found NUL => return pointer */
+
+	/* Fourth unroll.  */
+	movq (%rax), %rcx	/* get double word (= 8 bytes) in question */
+	addq $8,%rax		/* adjust pointer for next word */
+	movq %r8, %rdx		/* magic value */
+	addq %rcx, %rdx		/* add the magic value to the word.  We get
+				   carry bits reported for each byte which
+				   is *not* 0 */
+	jnc 3f			/* highest byte is NUL => return pointer */
+	xorq %rcx, %rdx		/* (word+magic)^word */
+	orq %r8, %rdx		/* set all non-carry bits */
+	incq %rdx		/* add 1: if one carry bit was *not* set
+				   the addition will not result in 0.  */
+	jz 4b			/* no NUL found => continue loop */
+
+	.p2align 4		/* Align, it's a jump target.  */
+3:	subq $8,%rax		/* correct pointer increment.  */
+
+	testb %cl, %cl		/* is first byte NUL? */
+	jz 2f			/* yes => return */
+	incq %rax		/* increment pointer */
+
+	testb %ch, %ch		/* is second byte NUL? */
+	jz 2f			/* yes => return */
+	incq %rax		/* increment pointer */
+
+	testl $0x00ff0000, %ecx /* is third byte NUL? */
+	jz 2f			/* yes => return pointer */
+	incq %rax		/* increment pointer */
+
+	testl $0xff000000, %ecx /* is fourth byte NUL? */
+	jz 2f			/* yes => return pointer */
+	incq %rax		/* increment pointer */
+
+	shrq $32, %rcx		/* look at other half.  */
+
+	testb %cl, %cl		/* is first byte NUL? */
+	jz 2f			/* yes => return */
+	incq %rax		/* increment pointer */
+
+	testb %ch, %ch		/* is second byte NUL? */
+	jz 2f			/* yes => return */
+	incq %rax		/* increment pointer */
+
+	testl $0xff0000, %ecx	/* is third byte NUL? */
+	jz 2f			/* yes => return pointer */
+	incq %rax		/* increment pointer */
+
+2:
+	/* Second step: Copy source to destination.  */
+
+	movq	%rsi, %rcx	/* duplicate  */
+	andl	$7,%ecx		/* mask alignment bits */
+	movq	%rax, %rdx	/* move around */
+	jz	22f		/* aligned => start loop */
+
+	neg	%ecx		/* align to 8 bytes.  */
+	addl	$8, %ecx
+	/* Align the source pointer.  */
+21:
+	movb	(%rsi), %al	/* Fetch a byte */
+	testb	%al, %al	/* Is it NUL? */
+	movb	%al, (%rdx)	/* Store it */
+	jz	24f		/* If it was NUL, done! */
+	incq	%rsi
+	incq	%rdx
+	decl	%ecx
+	jnz	21b
+
+	/* Now the sources is aligned.  Unfortunatly we cannot force
+	   to have both source and destination aligned, so ignore the
+	   alignment of the destination.  */
+	.p2align 4
+22:
+	/* 1st unroll.  */
+	movq	(%rsi), %rax	/* Read double word (8 bytes).  */
+	addq	$8, %rsi	/* Adjust pointer for next word.  */
+	movq	%rax, %r9	/* Save a copy for NUL finding.  */
+	addq	%r8, %r9	/* add the magic value to the word.  We get
+				   carry bits reported for each byte which
+				   is *not* 0 */
+	jnc	23f		/* highest byte is NUL => return pointer */
+	xorq	%rax, %r9	/* (word+magic)^word */
+	orq	%r8, %r9	/* set all non-carry bits */
+	incq	%r9		/* add 1: if one carry bit was *not* set
+				   the addition will not result in 0.  */
+
+	jnz	23f		/* found NUL => return pointer */
+
+	movq	%rax, (%rdx)	/* Write value to destination.  */
+	addq	$8, %rdx	/* Adjust pointer.  */
+
+	/* 2nd unroll.  */
+	movq	(%rsi), %rax	/* Read double word (8 bytes).  */
+	addq	$8, %rsi	/* Adjust pointer for next word.  */
+	movq	%rax, %r9	/* Save a copy for NUL finding.  */
+	addq	%r8, %r9	/* add the magic value to the word.  We get
+				   carry bits reported for each byte which
+				   is *not* 0 */
+	jnc	23f		/* highest byte is NUL => return pointer */
+	xorq	%rax, %r9	/* (word+magic)^word */
+	orq	%r8, %r9	/* set all non-carry bits */
+	incq	%r9		/* add 1: if one carry bit was *not* set
+				   the addition will not result in 0.  */
+
+	jnz	23f		/* found NUL => return pointer */
+
+	movq	%rax, (%rdx)	/* Write value to destination.  */
+	addq	$8, %rdx	/* Adjust pointer.  */
+
+	/* 3rd unroll.  */
+	movq	(%rsi), %rax	/* Read double word (8 bytes).  */
+	addq	$8, %rsi	/* Adjust pointer for next word.  */
+	movq	%rax, %r9	/* Save a copy for NUL finding.  */
+	addq	%r8, %r9	/* add the magic value to the word.  We get
+				   carry bits reported for each byte which
+				   is *not* 0 */
+	jnc	23f		/* highest byte is NUL => return pointer */
+	xorq	%rax, %r9	/* (word+magic)^word */
+	orq	%r8, %r9	/* set all non-carry bits */
+	incq	%r9		/* add 1: if one carry bit was *not* set
+				   the addition will not result in 0.  */
+
+	jnz	23f		/* found NUL => return pointer */
+
+	movq	%rax, (%rdx)	/* Write value to destination.  */
+	addq	$8, %rdx	/* Adjust pointer.  */
+
+	/* 4th unroll.  */
+	movq	(%rsi), %rax	/* Read double word (8 bytes).  */
+	addq	$8, %rsi	/* Adjust pointer for next word.  */
+	movq	%rax, %r9	/* Save a copy for NUL finding.  */
+	addq	%r8, %r9	/* add the magic value to the word.  We get
+				   carry bits reported for each byte which
+				   is *not* 0 */
+	jnc	23f		/* highest byte is NUL => return pointer */
+	xorq	%rax, %r9	/* (word+magic)^word */
+	orq	%r8, %r9	/* set all non-carry bits */
+	incq	%r9		/* add 1: if one carry bit was *not* set
+				   the addition will not result in 0.  */
+
+	jnz	23f		/* found NUL => return pointer */
+
+	movq	%rax, (%rdx)	/* Write value to destination.  */
+	addq	$8, %rdx	/* Adjust pointer.  */
+	jmp	22b		/* Next iteration.  */
+
+	/* Do the last few bytes. %rax contains the value to write.
+	   The loop is unrolled twice.  */
+	.p2align 4
+23:
+	movb	%al, (%rdx)	/* 1st byte.  */
+	testb	%al, %al	/* Is it NUL.  */
+	jz	24f		/* yes, finish.  */
+	incq	%rdx		/* Increment destination.  */
+	movb	%ah, (%rdx)	/* 2nd byte.  */
+	testb	%ah, %ah	/* Is it NUL?.  */
+	jz	24f		/* yes, finish.  */
+	incq	%rdx		/* Increment destination.  */
+	shrq	$16, %rax	/* Shift...  */
+	jmp	23b		/* and look at next two bytes in %rax.  */
+
+
+24:
+	movq	%rdi, %rax	/* Source is return value.  */
+	retq
+END (BP_SYM (strcat))