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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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c53c70a90f
This change cleans up the string code in a number of ways: - For memcpy(), fix bug in prefetch and increase distance to 3 lines; optimize for unaligned data; do all loads before wh64 to make memcpy safe for forward-overlapping calls; etc. Performance is improved. - Use new copy_byte() function on tilegx to spread a single byte value out into a full word using the shufflebytes instruction. - Clean up header include ordering to be more canonical, and remove spurious #undefs of function names. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
37 lines
1.1 KiB
C
37 lines
1.1 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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size_t strlen(const char *s)
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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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/* Read the first word, but force bytes before the string to be nonzero.
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* This expression works because we know shift counts are taken mod 32.
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*/
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uint32_t v = *p | ((1 << (s_int << 3)) - 1);
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uint32_t bits;
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while ((bits = __insn_seqb(v, 0)) == 0)
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v = *++p;
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return ((const char *)p) + (__insn_ctz(bits) >> 3) - s;
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}
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EXPORT_SYMBOL(strlen);
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