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d1dc791d11
libc_data_t is 8 bytes wide, so a buffer which is 4-byte but not 8-byte aligned falls back to the byte at a time loop. Add a 32-bit middle path so such buffers still handle four bytes per iteration. * Add DETECTNULL32/DETECTCHAR32, UNALIGNED4/UNALIGNED4_X, LITTLEBLOCKSIZE4/BIGBLOCKSIZE4 and TOO_SMALL4 to libs/libc/libc.h. * Take the new path in memccpy, memcmp, memcpy, memset, stpcpy, stpncpy, strcmp, strcpy, strncmp and strncpy when both pointers are 4-byte aligned but the 8-byte path can't be used. Assisted-by: Claude:claude-opus-5 Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
109 lines
2.9 KiB
C
109 lines
2.9 KiB
C
/****************************************************************************
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* libs/libc/string/lib_bsdstrncmp.c
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*
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* SPDX-License-Identifier: BSD
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* SPDX-FileCopyrightText: 1994-2009 Red Hat, Inc. All rights reserved
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*
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* Copyright (c) 1994-2009 Red Hat, Inc. All rights reserved.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the BSD License. This program is distributed in the hope that
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* it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
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* including the implied warranties of MERCHANTABILITY or FITNESS FOR
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* A PARTICULAR PURPOSE. A copy of this license is available at
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* http://www.opensource.org/licenses. Any Red Hat trademarks that are
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* incorporated in the source code or documentation are not subject to
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* the BSD License and may only be used or replicated with the express
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* permission of Red Hat, Inc.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <string.h>
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#include "libc.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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#if !defined(CONFIG_LIBC_ARCH_STRNCMP) && defined(LIBC_BUILD_STRNCMP)
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#undef strncmp
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no_builtin("strncmp")
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nosanitize_address
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int strncmp(FAR const char *cs, FAR const char *ct, size_t nb)
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{
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if (nb == 0)
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{
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return 0;
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}
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/* If cs or ct are unaligned, then compare bytes. */
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if (!UNALIGNED(cs, ct))
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{
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FAR libc_data_t *a1 = (FAR libc_data_t *)cs;
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FAR libc_data_t *a2 = (FAR libc_data_t *)ct;
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while (nb >= LITTLEBLOCKSIZE && *a1 == *a2)
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{
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nb -= LITTLEBLOCKSIZE;
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if (nb == 0 || DETECTNULL(*a1))
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{
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return 0;
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}
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a1++;
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a2++;
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}
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cs = (FAR char *)a1;
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ct = (FAR char *)a2;
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}
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else if (!UNALIGNED4(cs, ct))
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{
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FAR uint32_t *a1 = (FAR uint32_t *)cs;
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FAR uint32_t *a2 = (FAR uint32_t *)ct;
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while (nb >= LITTLEBLOCKSIZE4 && *a1 == *a2)
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{
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nb -= LITTLEBLOCKSIZE4;
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if (nb == 0 || DETECTNULL32(*a1))
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{
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return 0;
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}
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a1++;
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a2++;
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}
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cs = (FAR char *)a1;
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ct = (FAR char *)a2;
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}
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while (nb-- > 0 && *cs == *ct)
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{
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if (nb == 0 || *cs == '\0')
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{
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return 0;
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}
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cs++;
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ct++;
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}
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return *cs - *ct;
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}
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#endif
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