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author | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-26 02:35:32 +0400 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-05-26 02:35:32 +0400 |
commit | 0798b1dbfbd9ff2a370c5968c5f0621ef0075fe0 (patch) | |
tree | c7f61ab9683786a070da0933b9981fc74a4d865f /arch/tile/lib/memchr_64.c | |
parent | ad363e0916423b2e6cdfcdc30ae707ec709f0a65 (diff) | |
parent | 6738d3210aabe3016a1b03cd98a7fc479c229197 (diff) | |
download | linux-0798b1dbfbd9ff2a370c5968c5f0621ef0075fe0.tar.xz |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile
* git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile: (26 commits)
arch/tile: prefer "tilepro" as the name of the 32-bit architecture
compat: include aio_abi.h for aio_context_t
arch/tile: cleanups for tilegx compat mode
arch/tile: allocate PCI IRQs later in boot
arch/tile: support signal "exception-trace" hook
arch/tile: use better definitions of xchg() and cmpxchg()
include/linux/compat.h: coding-style fixes
tile: add an RTC driver for the Tilera hypervisor
arch/tile: finish enabling support for TILE-Gx 64-bit chip
compat: fixes to allow working with tile arch
arch/tile: update defconfig file to something more useful
tile: do_hardwall_trap: do not play with task->sighand
tile: replace mm->cpu_vm_mask with mm_cpumask()
tile,mn10300: add device parameter to dma_cache_sync()
audit: support the "standard" <asm-generic/unistd.h>
arch/tile: clarify flush_buffer()/finv_buffer() function names
arch/tile: kernel-related cleanups from removing static page size
arch/tile: various header improvements for building drivers
arch/tile: disable GX prefetcher during cache flush
arch/tile: tolerate disabling CONFIG_BLK_DEV_INITRD
...
Diffstat (limited to 'arch/tile/lib/memchr_64.c')
-rw-r--r-- | arch/tile/lib/memchr_64.c | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/arch/tile/lib/memchr_64.c b/arch/tile/lib/memchr_64.c new file mode 100644 index 000000000000..84fdc8d8e735 --- /dev/null +++ b/arch/tile/lib/memchr_64.c @@ -0,0 +1,71 @@ +/* + * Copyright 2011 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> + +void *memchr(const void *s, int c, size_t n) +{ + const uint64_t *last_word_ptr; + const uint64_t *p; + const char *last_byte_ptr; + uintptr_t s_int; + uint64_t goal, before_mask, v, bits; + char *ret; + + if (__builtin_expect(n == 0, 0)) { + /* Don't dereference any memory if the array is empty. */ + return NULL; + } + + /* Get an aligned pointer. */ + s_int = (uintptr_t) s; + p = (const uint64_t *)(s_int & -8); + + /* Create eight copies of the byte for which we are looking. */ + goal = 0x0101010101010101ULL * (uint8_t) c; + + /* Read the first word, but munge it so that bytes before the array + * will not match goal. + * + * Note that this shift count expression works because we know + * shift counts are taken mod 64. + */ + before_mask = (1ULL << (s_int << 3)) - 1; + v = (*p | before_mask) ^ (goal & before_mask); + + /* Compute the address of the last byte. */ + last_byte_ptr = (const char *)s + n - 1; + + /* Compute the address of the word containing the last byte. */ + last_word_ptr = (const uint64_t *)((uintptr_t) last_byte_ptr & -8); + + while ((bits = __insn_v1cmpeq(v, goal)) == 0) { + if (__builtin_expect(p == last_word_ptr, 0)) { + /* We already read the last word in the array, + * so give up. + */ + return NULL; + } + v = *++p; + } + + /* We found a match, but it might be in a byte past the end + * of the array. + */ + ret = ((char *)p) + (__insn_ctz(bits) >> 3); + return (ret <= last_byte_ptr) ? ret : NULL; +} +EXPORT_SYMBOL(memchr); |