Move arm from ports to libc.

I've moved the ARM port from ports to the main sysdeps hierarchy.
Beyond the README update, the move of the files was simply

git mv ports/sysdeps/arm sysdeps/arm
git mv ports/sysdeps/unix/arm sysdeps/unix/arm
git mv ports/sysdeps/unix/sysv/linux/arm sysdeps/unix/sysv/linux/arm

and in addition to the ChangeLog entries here, I put a note at the top
of ports/ChangeLog.arm similar to that at the top of
ChangeLog.powerpc.  There is deliberately no NEWS change, as I think
it makes the most sense to put in a general note above all ports
having moved if we can achieve that for 2.20.

Tested that disassembly of installed shared libraries for arm is the
same before and after this patch, except for data (not instructions)
in ld.so (there are assertions in sysdeps/arm/dl-machine.h, and the
path by which that file is found, and so by which it appears in the
assertion message, changes as a result of the move).

	* sysdeps/arm: Move directory from ports/sysdeps/arm.
	* sysdeps/unix/arm: Move directory from ports/sysdeps/unix/arm.
	* sysdeps/unix/sysv/linux/arm: Move directory from
	ports/sysdeps/unix/sysv/linux/arm.
	* README: Update listing for arm-*-linux-gnueabi.

ports/ChangeLog.arm:
	* sysdeps/arm: Move directory to ../sysdeps/arm.
	* sysdeps/unix/arm: Move directory to ../sysdeps.arm.
	* sysdeps/unix/sysv/linux/arm: Move directory to
	../sysdeps/unix/sysv/linux/arm.

1 files changed, 103 insertions, 0 deletions

diff --git a/sysdeps/arm/armv6/strlen.S b/sysdeps/arm/armv6/strlen.S
new file mode 100644
index 0000000..290d7bc
--- /dev/null
+++ b/sysdeps/arm/armv6/strlen.S
@@ -0,0 +1,103 @@
+/* strlen -- find the length of a nul-terminated string.
+   Copyright (C) 2013-2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+	.syntax unified
+	.text
+
+ENTRY (strlen)
+	@ r0 = start of string
+	sfi_breg r0, \
+	ldrb	r2, [\B]		@ load the first byte asap
+
+	@ To cater to long strings, we want to search through a few
+	@ characters until we reach an aligned pointer.  To cater to
+	@ small strings, we don't want to start doing word operations
+	@ immediately.  The compromise is a maximum of 16 bytes less
+	@ whatever is required to end with an aligned pointer.
+	@ r3 = number of characters to search in alignment loop
+	and	r3, r0, #7
+	mov	r1, r0			@ Save the input pointer
+	rsb	r3, r3, #15		@ 16 - 1 peeled loop iteration
+	cmp	r2, #0
+	beq	99f
+
+	@ Loop until we find ...
+1:	sfi_breg r0, \
+	ldrb	r2, [\B, #1]!
+	subs	r3, r3, #1		@ ... the aligment point
+	it	ne
+	cmpne	r2, #0			@ ... or EOS
+	bne	1b
+
+	@ Disambiguate the exit possibilites above
+	cmp	r2, #0			@ Found EOS
+	beq	99f
+	add	r0, r0, #1
+
+	@ So now we're aligned.
+	sfi_breg r0, \
+	ldrd	r2, r3, [\B], #8
+#ifdef ARCH_HAS_T2
+	movw	ip, #0x0101
+	sfi_pld	r0, #64
+	movt	ip, #0x0101
+#else
+	ldr	ip, =0x01010101
+	sfi_pld	r0, #64
+#endif
+
+	@ Loop searching for EOS, 8 bytes at a time.
+	@ Subtracting (unsigned saturating) from 1 for any byte means that
+	@ we get 1 for any byte that was originally zero and 0 otherwise.
+	@ Therefore we consider the lsb of each byte the "found" bit.
+	.balign	16
+2:	uqsub8	r2, ip, r2		@ Find EOS
+	uqsub8	r3, ip, r3
+	sfi_pld	r0, #128		@ Prefetch 2 lines ahead
+	orrs	r3, r3, r2		@ Combine the two words
+	it	eq
+	sfi_breg r0, \
+	ldrdeq	r2, r3, [\B], #8
+	beq	2b
+
+	@ Found something.  Disambiguate between first and second words.
+	@ Adjust r0 to point to the word containing the match.
+	@ Adjust r2 to the found bits for the word containing the match.
+	cmp	r2, #0
+	sub	r0, r0, #4
+	ite	eq
+	moveq	r2, r3
+	subne	r0, r0, #4
+
+	@ Find the bit-offset of the match within the word.  Note that the
+	@ bit result from clz will be 7 higher than "true", but we'll
+	@ immediately discard those bits converting to a byte offset.
+#ifdef __ARMEL__
+	rev	r2, r2			@ For LE, count from the little end
+#endif
+	clz	r2, r2
+	add	r0, r0, r2, lsr #3	@ Adjust the pointer to the found byte
+99:
+	sub	r0, r0, r1		@ Subtract input to compute length
+	bx	lr
+
+END (strlen)
+
+libc_hidden_builtin_def (strlen)