linux/arch/tile/lib/memchr_64.c
Chris Metcalf 18aecc2b64 arch/tile: finish enabling support for TILE-Gx 64-bit chip
This support was partially present in the existing code (look for
"__tilegx__" ifdefs) but with this change you can build a working
kernel using the TILE-Gx toolchain and ARCH=tilegx.

Most of these files are new, generally adding a foo_64.c file
where previously there was just a foo_32.c file.

The ARCH=tilegx directive redirects to arch/tile, not arch/tilegx,
using the existing SRCARCH mechanism in the top-level Makefile.

Changes to existing files:

- <asm/bitops.h> and <asm/bitops_32.h> changed to factor the
  include of <asm-generic/bitops/non-atomic.h> in the common header.

- <asm/compat.h> and arch/tile/kernel/compat.c changed to remove
  the "const" markers I had put on compat_sys_execve() when trying
  to match some recent similar changes to the non-compat execve.
  It turns out the compat version wasn't "upgraded" to use const.

- <asm/opcode-tile_64.h> and <asm/opcode_constants_64.h> were
  previously included accidentally, with the 32-bit contents.  Now
  they have the proper 64-bit contents.

Finally, I had to hack the existing hacky drivers/input/input-compat.h
to add yet another "#ifdef" for INPUT_COMPAT_TEST (same as x86_64).

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> [drivers/input]
2011-05-12 15:52:12 -04:00

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2.0 KiB
C

/*
* 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);