diff options
Diffstat (limited to 'sysdeps/ia64/strlen.S')
-rw-r--r-- | sysdeps/ia64/strlen.S | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/sysdeps/ia64/strlen.S b/sysdeps/ia64/strlen.S new file mode 100644 index 0000000000..5930af7b32 --- /dev/null +++ b/sysdeps/ia64/strlen.S @@ -0,0 +1,97 @@ +/* Optimized version of the standard strlen() function. + This file is part of the GNU C Library. + Copyright (C) 2000-2014 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) |