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867e359b97
This change is the core kernel support for TILEPro and TILE64 chips. No driver support (except the console driver) is included yet. This includes the relevant Linux headers in asm/; the low-level low-level "Tile architecture" headers in arch/, which are shared with the hypervisor, etc., and are build-system agnostic; and the relevant hypervisor headers in hv/. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Reviewed-by: Paul Mundt <lethal@linux-sh.org>
69 lines
2.0 KiB
C
69 lines
2.0 KiB
C
/*
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* Copyright 2010 Tilera Corporation. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for
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* more details.
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*/
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/module.h>
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void *memchr(const void *s, int c, size_t n)
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{
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/* Get an aligned pointer. */
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const uintptr_t s_int = (uintptr_t) s;
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const uint32_t *p = (const uint32_t *)(s_int & -4);
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/* Create four copies of the byte for which we are looking. */
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const uint32_t goal = 0x01010101 * (uint8_t) c;
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/* Read the first word, but munge it so that bytes before the array
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* will not match goal.
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*
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* Note that this shift count expression works because we know
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* shift counts are taken mod 32.
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*/
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const uint32_t before_mask = (1 << (s_int << 3)) - 1;
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uint32_t v = (*p | before_mask) ^ (goal & before_mask);
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/* Compute the address of the last byte. */
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const char *const last_byte_ptr = (const char *)s + n - 1;
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/* Compute the address of the word containing the last byte. */
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const uint32_t *const last_word_ptr =
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(const uint32_t *)((uintptr_t) last_byte_ptr & -4);
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uint32_t bits;
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char *ret;
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if (__builtin_expect(n == 0, 0)) {
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/* Don't dereference any memory if the array is empty. */
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return NULL;
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}
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while ((bits = __insn_seqb(v, goal)) == 0) {
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if (__builtin_expect(p == last_word_ptr, 0)) {
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/* We already read the last word in the array,
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* so give up.
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*/
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return NULL;
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}
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v = *++p;
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}
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/* We found a match, but it might be in a byte past the end
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* of the array.
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*/
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ret = ((char *)p) + (__insn_ctz(bits) >> 3);
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return (ret <= last_byte_ptr) ? ret : NULL;
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}
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EXPORT_SYMBOL(memchr);
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