linux/arch/tile/lib/strchr_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

68 lines
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>
#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 uint64_t *p = (const uint64_t *)(s_int & -8);
/* Create eight copies of the byte for which we are looking. */
const uint64_t goal = 0x0101010101010101ULL * (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 64.
*/
const uint64_t before_mask = (1ULL << (s_int << 3)) - 1;
uint64_t v = (*p | before_mask) ^
(goal & __insn_v1shrsi(before_mask, 1));
uint64_t zero_matches, goal_matches;
while (1) {
/* Look for a terminating '\0'. */
zero_matches = __insn_v1cmpeqi(v, 0);
/* Look for the goal byte. */
goal_matches = __insn_v1cmpeq(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;
}
EXPORT_SYMBOL(strchr);