diff options
Diffstat (limited to 'ports/sysdeps/tile/tilepro/strchr.c')
-rw-r--r-- | ports/sysdeps/tile/tilepro/strchr.c | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/ports/sysdeps/tile/tilepro/strchr.c b/ports/sysdeps/tile/tilepro/strchr.c new file mode 100644 index 0000000000..8615000e50 --- /dev/null +++ b/ports/sysdeps/tile/tilepro/strchr.c @@ -0,0 +1,68 @@ +/* Copyright (C) 2011 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> + +#undef strchr + +char * +strchr (const char *s, int c) +{ + int z, g; + + /* 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)); + + 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 (__builtin_expect ((zero_matches | goal_matches) != 0, 0)) + break; + + v = *++p; + } + + z = __insn_ctz (zero_matches); + g = __insn_ctz (goal_matches); + + /* If we found c before '\0' we got a match. Note that if c == '\0' + then g == z, and we correctly return the address of the '\0' + rather than NULL. */ + return (g <= z) ? ((char *) p) + (g >> 3) : NULL; +} +weak_alias (strchr, index) +libc_hidden_builtin_def (strchr) |