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author | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
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committer | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
commit | 871480933a1c28f8a9fed4c4d34d06c439a7a422 (patch) | |
tree | 8718f573808810c2a1e8cb8fb6ac469093ca2784 /arch/tile/lib/strchr_32.c | |
parent | 9d40ac5867b9aefe0722bc1f110b965ff294d30d (diff) | |
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Moved, renamed, and deleted files
The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.
Diffstat (limited to 'arch/tile/lib/strchr_32.c')
-rw-r--r-- | arch/tile/lib/strchr_32.c | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/arch/tile/lib/strchr_32.c b/arch/tile/lib/strchr_32.c new file mode 100644 index 00000000..c94e6f7a --- /dev/null +++ b/arch/tile/lib/strchr_32.c @@ -0,0 +1,66 @@ +/* + * Copyright 2010 Tilera Corporation. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * This program 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, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + */ + +#include <linux/types.h> +#include <linux/string.h> +#include <linux/module.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)) + 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; +} +EXPORT_SYMBOL(strchr); |