162 lines
4.2 KiB
C
162 lines
4.2 KiB
C
/****************************************************************************
|
|
* libs/libc/string/lib_bsdstrchr.c
|
|
*
|
|
* Copyright (c) 1994-2009 Red Hat, Inc. All rights reserved.
|
|
*
|
|
* This copyrighted material is made available to anyone wishing to use,
|
|
* modify, copy, or redistribute it subject to the terms and conditions
|
|
* of the BSD License. This program is distributed in the hope that
|
|
* it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
|
|
* including the implied warranties of MERCHANTABILITY or FITNESS FOR
|
|
* A PARTICULAR PURPOSE. A copy of this license is available at
|
|
* http://www.opensource.org/licenses. Any Red Hat trademarks that are
|
|
* incorporated in the source code or documentation are not subject to
|
|
* the BSD License and may only be used or replicated with the express
|
|
* permission of Red Hat, Inc.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include <nuttx/config.h>
|
|
|
|
#include <string.h>
|
|
|
|
#include "libc.h"
|
|
|
|
/****************************************************************************
|
|
* Pre-processor Definitions
|
|
****************************************************************************/
|
|
|
|
#define UNALIGNED(x) ((long)(uintptr_t)(x) & (sizeof(long) - 1))
|
|
|
|
/* How many bytes are loaded each iteration of the word copy loop. */
|
|
|
|
#define LBLOCKSIZE (sizeof(long))
|
|
|
|
/* Macros for detecting endchar */
|
|
|
|
#if LONG_MAX == 2147483647
|
|
# define DETECTNULL(x) (((x) - 0x01010101) & ~(x) & 0x80808080)
|
|
#elif LONG_MAX == 9223372036854775807
|
|
/* Nonzero if x (a long int) contains a NULL byte. */
|
|
|
|
# define DETECTNULL(x) (((x) - 0x0101010101010101) & ~(x) & 0x8080808080808080)
|
|
#endif
|
|
|
|
#define DETECTCHAR(x, mask) (DETECTNULL((x) ^ (mask)))
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: strchr
|
|
*
|
|
* Description:
|
|
* The strchr() function locates the first occurrence of 'c' (converted to
|
|
* a char) in the string pointed to by 's'. The terminating null byte is
|
|
* considered to be part of the string.
|
|
*
|
|
* Returned Value:
|
|
* Upon completion, strchr() returns a pointer to the byte, or a null
|
|
* pointer if the byte was not found.
|
|
*
|
|
****************************************************************************/
|
|
|
|
#if !defined(CONFIG_LIBC_ARCH_STRCHR) && defined(LIBC_BUILD_STRCHR)
|
|
#undef strchr /* See mm/README.txt */
|
|
nosanitize_address
|
|
FAR char *strchr(FAR const char *s, int c)
|
|
{
|
|
FAR const unsigned char *s1 = (FAR const unsigned char *)s;
|
|
FAR unsigned long *aligned_addr;
|
|
unsigned char i = c;
|
|
unsigned long mask;
|
|
unsigned long j;
|
|
|
|
/* Special case for finding 0. */
|
|
|
|
if (!i)
|
|
{
|
|
while (UNALIGNED(s1))
|
|
{
|
|
if (!*s1)
|
|
{
|
|
return (FAR char *)s1;
|
|
}
|
|
|
|
s1++;
|
|
}
|
|
|
|
/* Operate a word at a time. */
|
|
|
|
aligned_addr = (FAR unsigned long *)s1;
|
|
while (!DETECTNULL(*aligned_addr))
|
|
{
|
|
aligned_addr++;
|
|
}
|
|
|
|
/* Found the end of string. */
|
|
|
|
s1 = (FAR const unsigned char *)aligned_addr;
|
|
while (*s1)
|
|
{
|
|
s1++;
|
|
}
|
|
|
|
return (FAR char *)s1;
|
|
}
|
|
|
|
/* All other bytes. Align the pointer, then search a long at a time. */
|
|
|
|
while (UNALIGNED(s1))
|
|
{
|
|
if (!*s1)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
if (*s1 == i)
|
|
{
|
|
return (FAR char *)s1;
|
|
}
|
|
|
|
s1++;
|
|
}
|
|
|
|
mask = i;
|
|
for (j = 8; j < LBLOCKSIZE * 8; j <<= 1)
|
|
{
|
|
mask = (mask << j) | mask;
|
|
}
|
|
|
|
aligned_addr = (FAR unsigned long *)s1;
|
|
while (!DETECTNULL(*aligned_addr) && !DETECTCHAR(*aligned_addr, mask))
|
|
{
|
|
aligned_addr++;
|
|
}
|
|
|
|
/* The block of bytes currently pointed to by aligned_addr
|
|
* contains either a null or the target char, or both. We
|
|
* catch it using the bytewise search.
|
|
*/
|
|
|
|
s1 = (FAR unsigned char *)aligned_addr;
|
|
|
|
while (*s1 && *s1 != i)
|
|
{
|
|
s1++;
|
|
}
|
|
|
|
if (*s1 == i)
|
|
{
|
|
return (FAR char *)s1;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
#endif
|