diff options
Diffstat (limited to 'sysdeps/tile/tilepro/strrchr.c')
| -rw-r--r-- | sysdeps/tile/tilepro/strrchr.c | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/sysdeps/tile/tilepro/strrchr.c b/sysdeps/tile/tilepro/strrchr.c new file mode 100644 index 0000000000..1c7f5e7014 --- /dev/null +++ b/sysdeps/tile/tilepro/strrchr.c @@ -0,0 +1,73 @@ +/* Copyright (C) 2011-2014 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011. + + 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 <string.h> +#include <stdint.h> + +char * +strrchr (const char *s, int c) +{ + /* Get an aligned pointer. */ + const uintptr_t s_int = (uintptr_t) s; + const uint32_t *p = (const uint32_t *) (s_int & -4); + + /* Create four copies of the byte for which we are looking. */ + const uint32_t goal = 0x01010101 * (uint8_t) c; + + /* Read the first aligned word, but force bytes before the string to + match neither zero nor goal (we make sure the high bit of each + byte is 1, and the low 7 bits are all the opposite of the goal + byte). Note that this shift count expression works because we + know shift counts are taken mod 32. */ + const uint32_t before_mask = (1 << (s_int << 3)) - 1; + uint32_t v = (*p | before_mask) ^ (goal & __insn_shrib (before_mask, 1)); + const char *found = NULL; + uint32_t zero_matches, goal_matches; + while (1) + { + /* Look for a terminating '\0'. */ + zero_matches = __insn_seqb (v, 0); + + /* Look for the goal byte. */ + goal_matches = __insn_seqb (v, goal); + + /* If we found the goal, record the last offset. */ + if (__builtin_expect (goal_matches != 0, 0)) + { + if (__builtin_expect (zero_matches != 0, 0)) + { + /* Clear any goal after the first zero. */ + int first_nul = __insn_ctz (zero_matches); + /* The number of top bits we need to clear is + 32 - (first_nul + 8). */ + int shift_amt = (24 - first_nul); + goal_matches <<= shift_amt; + goal_matches >>= shift_amt; + } + if (__builtin_expect (goal_matches != 0, 1)) + found = ((char *) p) + 3 - (__insn_clz (goal_matches) >> 3); + } + + if (__builtin_expect (zero_matches != 0, 0)) + return (char *) found; + + v = *++p; + } +} +weak_alias (strrchr, rindex) +libc_hidden_builtin_def (strrchr) |