98 lines
2.8 KiB
ArmAsm
98 lines
2.8 KiB
ArmAsm
/* Optimized version of the standard strlen() function.
|
|
This file is part of the GNU C Library.
|
|
Copyright (C) 2000, 2001 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, write to the Free
|
|
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
|
02111-1307 USA. */
|
|
|
|
/* 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)
|