/* Optimized version of the standard strlen() function.

   This file is part of the GNU C Library.

   Copyright (C) 2000-2018 Free Software Foundation, Inc.

   Contributed by Dan Pop <Dan.Pop@cern.ch>.

   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/>.  */

/* Return: the length of the input string

   Input:

        in0:    str

   Look for the null character byte by byte, until we reach a word aligned

   address, then search word by word, using the czx instruction.  We're

   also doing one word of read ahead, which could cause problems if the

   null character is on the last word of a page and the next page is not

   mapped in the process address space.  Hence the use of the speculative

   load.

   This implementation assumes little endian mode.  For big endian mode,

   the instruction czx1.r should be replaced by czx1.l.  */

#include <sysdep.h>

#undef ret

#define saved_lc	r18

#define str		r19

#define pos0		r20

#define val1		r21

#define val2		r22

#define origadd		r23

#define tmp		r24

#define loopcnt		r30

#define len		ret0

ENTRY(strlen)

	.prologue

	alloc r2 = ar.pfs, 1, 0, 0, 0

	.save ar.lc, saved_lc

        mov 	saved_lc = ar.lc 	// save the loop counter

	.body

	mov 	str = in0

	mov 	len = r0		// len = 0

	and 	tmp = 7, in0		// tmp = str % 8

	;;

	sub	loopcnt = 8, tmp	// loopcnt = 8 - tmp

	cmp.eq	p6, p0 = tmp, r0

(p6)	br.cond.sptk	.str_aligned;;

	adds	loopcnt = -1, loopcnt;;

	mov	ar.lc = loopcnt

.l1:

	ld1	val2 = [str], 1

	;;

	cmp.eq	p6, p0 = val2, r0

(p6)	br.cond.spnt	.restore_and_exit

	adds	len = 1, len

	br.cloop.dptk	.l1

.str_aligned:

	mov	origadd = str		// origadd = orig

	ld8	val1 = [str], 8;;

	nop.b	0

	nop.b 	0

.l2:	ld8.s	val2 = [str], 8		// don't bomb out here

	czx1.r	pos0 = val1

	;;

	cmp.ne	p6, p0 = 8, pos0

(p6)	br.cond.spnt .foundit

	chk.s	val2, .recovery

.back:

	mov	val1 = val2

	br.cond.dptk	.l2

.foundit:

	sub	tmp = str, origadd	// tmp = crt address - orig

	add	len = len, pos0;;

	add	len = len, tmp;;

	adds	len = -16, len

.restore_and_exit:

	mov ar.lc = saved_lc		// restore the loop counter

	br.ret.sptk.many b0

.recovery:

	adds	str = -8, str;;

	ld8	val2 = [str], 8		// bomb out here

	br.cond.sptk	.back

END(strlen)

libc_hidden_builtin_def (strlen)