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nuttx/libs/libc/libc.h
Xiang Xiao d1dc791d11 libs/libc/string: Add 4-byte alignment middle path for BSD functions. 
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>
2026-08-17 10:47:33 +02:00

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/****************************************************************************
* libs/libc/libc.h
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
#ifndef __LIBS_LIBC_LIBC_H
#define __LIBS_LIBC_LIBC_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#ifndef __ASSEMBLY__
# include <sys/types.h>
# include <stdbool.h>
# include <stdio.h>
# include <stdlib.h>
# include <limits.h>
# include <semaphore.h>
# include <nuttx/lib/lib.h>
# include <nuttx/streams.h>
#endif
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* This configuration directory is used in environment variable processing
* when we need to reference the user's home directory. There are no user
* directories in NuttX so, by default, this always refers to the root
* directory.
*/
#ifndef CONFIG_LIBC_HOMEDIR
# define CONFIG_LIBC_HOMEDIR "/"
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_MEMCHR_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_MEMCHR_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_MEMCHR
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_MEMCMP_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_MEMCMP_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_MEMCMP
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_MEMCPY_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_MEMCPY_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_MEMCPY
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_MEMMOVE_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_MEMMOVE_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_MEMMOVE
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_MEMSET_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_MEMSET_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_MEMSET
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRCAT_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRCAT_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRCAT
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRCASECMP_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRCASECMP_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRCASECMP
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRCHR_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRCHR_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRCHR
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRCHRNUL_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRCHRNUL_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRCHRNUL
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRCMP_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRCMP_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRCMP
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRCPY_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRCPY_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRCPY
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRLCAT_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRLCAT_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRLCAT
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRLEN_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRLEN_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRLEN
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRLCPY_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRLCPY_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRLCPY
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRNCASECMP_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRNCASECMP_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRNCASECMP
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRNCAT_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRNCAT_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRNCAT
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRNLEN_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRNLEN_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRNLEN
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRNCMP_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRNCMP_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRNCMP
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRNCPY_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRNCPY_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRNCPY
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STRRCHR_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STRRCHR_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STRRCHR
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STPCPY_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STPCPY_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STPCPY
#endif
#if ((!defined(CONFIG_LIBC_PREVENT_STPNCPY_USER) && !defined(__KERNEL__)) || \
(!defined(CONFIG_LIBC_PREVENT_STPNCPY_KERNEL) && defined(__KERNEL__)))
# define LIBC_BUILD_STPNCPY
#endif
#ifdef CONFIG_MM_KASAN
# define ARCH_LIBCFUN(x) arch_##x
#else
# define ARCH_LIBCFUN(x) x
#endif
/* Nonzero if either x or y is not aligned on a "libc_data_t" boundary. */
#define UNALIGNED_X(x) \
(((libc_data_t)(uintptr_t)(x) & (sizeof(libc_data_t) - 1)) != 0)
#define UNALIGNED(x, y) ((UNALIGNED_X(x)) | (UNALIGNED_X(y)))
#define ALIGNED(x) \
(((libc_data_t)(uintptr_t)(x) & (sizeof(libc_data_t) - 1)) == 0)
/* How many bytes are copied each iteration of the word copy loop. */
#define LITTLEBLOCKSIZE (sizeof(libc_data_t))
#define BIGBLOCKSIZE (sizeof(libc_data_t) << 2)
/* Threshold for punting to the byte copier. */
#define TOO_SMALL(len) ((len) < LITTLEBLOCKSIZE)
/* Macros for detecting endchar */
#define DETECTNULL(x) \
(((x) - 0x0101010101010101LL) & ~(x) & 0x8080808080808080LL)
#define DETECTCHAR(x, mask) (DETECTNULL((x) ^ (mask)))
/* 32-bit helpers for the 4-byte middle path on 64-bit platforms.
* When libc_data_t is 8 bytes, pointers that are 4-byte aligned
* but not 8-byte aligned would otherwise fall back to byte-at-a-time.
*/
#define DETECTNULL32(x) \
(((x) - (uint32_t)0x01010101) & ~(x) & (uint32_t)0x80808080)
#define DETECTCHAR32(x, mask) (DETECTNULL32((x) ^ (mask)))
#define UNALIGNED4(x, y) \
((((uintptr_t)(x)) | ((uintptr_t)(y))) & 3)
#define UNALIGNED4_X(x) (((uintptr_t)(x)) & 3)
#define LITTLEBLOCKSIZE4 (sizeof(uint32_t))
#define BIGBLOCKSIZE4 (sizeof(uint32_t) << 2)
#define TOO_SMALL4(len) ((len) < LITTLEBLOCKSIZE4)
#ifndef __ASSEMBLY__
/****************************************************************************
* Public Types
****************************************************************************/
typedef unsigned long long libc_data_t;
/****************************************************************************
* Public Data
****************************************************************************/
#undef EXTERN
#if defined(__cplusplus)
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
/* Defined in lib_getfullpath.c */
int lib_getfullpath(int dirfd, FAR const char *path,
FAR char *fullpath, size_t fulllen);
/* Defined in lib_fopen.c */
int lib_mode2oflags(FAR const char *mode);
/* Defined in lib_libfwrite.c */
ssize_t lib_fwrite(FAR const void *ptr, size_t count, FAR FILE *stream);
ssize_t lib_fwrite_unlocked(FAR const void *ptr, size_t count,
FAR FILE *stream);
/* Defined in lib_libfread_unlocked.c */
ssize_t lib_fread_unlocked(FAR void *ptr, size_t count, FAR FILE *stream);
/* Defined in lib_libgets.c */
FAR char *lib_dgets(FAR char *buf, size_t buflen, int fd,
bool keepnl, bool consume);
/* Defined in lib_libfgets.c */
FAR char *lib_fgets(FAR char *buf, size_t buflen, FILE *stream,
bool keepnl, bool consume);
FAR char *lib_fgets_unlocked(FAR char *buf, size_t buflen, FILE *stream,
bool keepnl, bool consume);
/* Defined in lib_flushall.c */
#ifdef CONFIG_FILE_STREAM
int lib_flushall(FAR struct streamlist *list);
int lib_flushall_unlocked(FAR struct streamlist *list);
#endif
/* Defined in lib_libfflush.c */
ssize_t lib_fflush(FAR FILE *stream);
ssize_t lib_fflush_unlocked(FAR FILE *stream);
/* Defined in lib_rdflush_unlocked.c */
int lib_rdflush_unlocked(FAR FILE *stream);
/* Defined in lib_wrflush_unlocked.c */
int lib_wrflush_unlocked(FAR FILE *stream);
/* Defined in lib_libgetbase.c */
int lib_getbase(FAR const char *nptr, FAR const char **endptr);
/* Defined in lib_skipspace.c */
void lib_skipspace(FAR const char **pptr);
/* Defined in lib_isbasedigit.c */
bool lib_isbasedigit(int ch, int base, FAR int *value);
/* Defined in lib_checkbase.c */
int lib_checkbase(int base, FAR const char **pptr);
/* Defined in lib_parsehostfile.c */
#ifdef CONFIG_NETDB_HOSTFILE
struct hostent;
ssize_t lib_parse_hostfile(FAR FILE *stream, FAR struct hostent *host,
FAR char *buf, size_t buflen);
#endif
#ifndef CONFIG_DISABLE_ENVIRON
int lib_restoredir(void);
#endif
/* Defined in lib_cxx_initialize.c */
void lib_cxx_initialize(void);
#undef EXTERN
#if defined(__cplusplus)
}
#endif
#endif /* __ASSEMBLY__ */
#endif /* __LIBS_LIBC_LIBC_H */
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