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bd6b226546
Most hardware accesses the memory through a 64-bit bus, so handle the data in 64-bit chunks instead of "long" chunks which are only 32-bit wide on the 32-bit platforms. * Add the libc_data_t type (unsigned long long) and move the shared UNALIGNED/UNALIGNED_X/ALIGNED, LITTLEBLOCKSIZE, TOO_SMALL and DETECTNULL helpers from the individual C files to libs/libc/libc.h. * Convert all lib_bsd*.c implementations to the new type and macros, which also drops the duplicated LONG_MAX conditionals. Assisted-by: Claude:claude-opus-5 Signed-off-by: anjiahao <anjiahao@xiaomi.com>
151 lines
3.9 KiB
C
151 lines
3.9 KiB
C
/****************************************************************************
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* libs/libc/string/lib_bsdstrchr.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 <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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#define DETECTCHAR(x, mask) (DETECTNULL((x) ^ (mask)))
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: strchr
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*
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* Description:
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* The strchr() function locates the first occurrence of 'c' (converted to
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* a char) in the string pointed to by 's'. The terminating null byte is
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* considered to be part of the string.
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*
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* Returned Value:
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* Upon completion, strchr() returns a pointer to the byte, or a null
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* pointer if the byte was not found.
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*
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****************************************************************************/
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#if !defined(CONFIG_LIBC_ARCH_STRCHR) && defined(LIBC_BUILD_STRCHR)
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#undef strchr
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no_builtin("strchr")
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nosanitize_address
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FAR char *strchr(FAR const char *s, int c)
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{
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FAR const unsigned char *s1 = (FAR const unsigned char *)s;
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FAR libc_data_t *aligned_addr;
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unsigned char i = c;
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libc_data_t mask;
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libc_data_t j;
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/* Special case for finding 0. */
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if (!i)
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{
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while (UNALIGNED_X(s1))
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{
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if (!*s1)
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{
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return (FAR char *)s1;
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}
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s1++;
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}
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/* Operate a word at a time. */
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aligned_addr = (FAR libc_data_t *)s1;
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while (!DETECTNULL(*aligned_addr))
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{
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aligned_addr++;
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}
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/* Found the end of string. */
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s1 = (FAR const unsigned char *)aligned_addr;
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while (*s1)
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{
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s1++;
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}
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return (FAR char *)s1;
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}
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/* All other bytes. Align the pointer,
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* then search a libc_data_t at a time.
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*/
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while (UNALIGNED_X(s1))
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{
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if (!*s1)
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{
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return NULL;
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}
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if (*s1 == i)
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{
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return (FAR char *)s1;
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}
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s1++;
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}
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mask = i;
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for (j = 8; j < LITTLEBLOCKSIZE * 8; j <<= 1)
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{
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mask = (mask << j) | mask;
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}
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aligned_addr = (FAR libc_data_t *)s1;
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while (!DETECTNULL(*aligned_addr) && !DETECTCHAR(*aligned_addr, mask))
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{
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aligned_addr++;
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}
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/* The block of bytes currently pointed to by aligned_addr
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* contains either a null or the target char, or both. We
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* catch it using the bytewise search.
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*/
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s1 = (FAR unsigned char *)aligned_addr;
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while (*s1 && *s1 != i)
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{
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s1++;
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}
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if (*s1 == i)
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{
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return (FAR char *)s1;
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}
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return NULL;
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}
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#endif
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