EDA365电子论坛网

标题: 分享linux下的string库函数 [打印本页]

作者: mytomorrow 时间: 2019-9-18 14:39
标题: 分享linux下的string库函数

/ G% D/ k$ x1 ]/ S
/*
* linux/lib/string.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*/
8 z# k. L. F9 r. V, Q/ V8 w' ^9 ]
/*
* stupid library routines.. The optimized versions should generally be found
* as inline code in <asm-xx/string.h>
*
* These are buggy as well..
*
* * Fri Jun 25 1999, Ingo Oeser
* - Added strsep() which will replace strtok() soon (because strsep() is
* reentrant and should be faster). Use only strsep() in new code, please.
*
* * Sat Feb 09 2002, Jason Thomas ,
* Matthew Hawkins
* - Kissed strtok() goodbye
*/
; E% ?3 C' G& Z% B0 P
#include <linux/types.h>
#include <linux/string.h>
#include <linux/ctype.h>
#include <linux/module.h>
& l. U0 M( L/ L6 Q' U0 T% a O
#ifndef __HAVE_ARCH_STRNICMP
/**
* strnicmp - Case insensitive, length-limited string comparison
* @s1: One string
* @s2: The other string
* @len: the maximum number of characters to compare
*/
int strnicmp(const char *s1, const char *s2, size_t len)
{
/* Yes, Virginia, it had better be unsigned */
unsigned char c1, c2;
" {" T. J4 Y% K: k8 H
c1 = 0; c2 = 0;
if (len) {
do {
c1 = *s1; c2 = *s2;
s1++; s2++;
if (!c1)
break;
if (!c2)
break;
if (c1 == c2)
continue;
c1 = tolower(c1);
c2 = tolower(c2);
if (c1 != c2)
break;
} while (--len);
}
return (int)c1 - (int)c2;
}
' ?; _1 k6 f1 h! B- B# p
EXPORT_SYMBOL(strnicmp);
#endif
: {' p4 ]7 S, Z0 s4 ]; V0 f
#ifndef __HAVE_ARCH_STRCPY
/**
* strcpy - Copy a %NUL terminated string
* @dest: Where to copy the string to
* @src: Where to copy the string from
*/
#undef strcpy
char * strcpy(char * dest,const char *src)
{
char *tmp = dest;
# D: {6 j! A3 D. B8 F3 y
while ((*dest++ = *src++) != '/0')
/* nothing */;
return tmp;
}
EXPORT_SYMBOL(strcpy);
#endif
/ w8 U+ Y% S: i% q
#ifndef __HAVE_ARCH_STRNCPY
/**
* strncpy - Copy a length-limited, %NUL-terminated string
* @dest: Where to copy the string to
* @src: Where to copy the string from
* @count: The maximum number of bytes to copy
*
* The result is not %NUL-terminated if the source exceeds
* @count bytes.
*
* In the case where the length of @src is less than that of
* count, the remainder of @dest will be padded with %NUL.
*
*/
char * strncpy(char * dest,const char *src,size_t count)
{
char *tmp = dest;
" G. O6 ~( J' `% O- U" U
while (count) {
if ((*tmp = *src) != 0) src++;
tmp++;
count--;
}
return dest;
}
EXPORT_SYMBOL(strncpy);
#endif
?) Q4 u5 v8 A" R. E+ S3 V
#ifndef __HAVE_ARCH_STRLCPY
/**
* strlcpy - Copy a %NUL terminated string into a sized buffer
* @dest: Where to copy the string to
* @src: Where to copy the string from
* @size: size of destination buffer
*
* Compatible with *BSD: the result is always a valid
* NUL-terminated string that fits in the buffer (unless,
* of course, the buffer size is zero). It does not pad
* out the result like strncpy() does.
*/
size_t strlcpy(char *dest, const char *src, size_t size)
{
size_t ret = strlen(src);
' q; b5 E8 r- [% I3 A
if (size) {
size_t len = (ret >= size) ? size-1 : ret;
memcpy(dest, src, len);
dest[len] = '/0';
}
return ret;
}
EXPORT_SYMBOL(strlcpy);
#endif
8 `8 c! W% I0 M$ @
#ifndef __HAVE_ARCH_STRCAT
/**
* strcat - Append one %NUL-terminated string to another
* @dest: The string to be appended to
* @src: The string to append to it
*/
#undef strcat
char * strcat(char * dest, const char * src)
{
char *tmp = dest;
1 g/ L! s" j M# `( n; p
while (*dest)
dest++;
while ((*dest++ = *src++) != '/0')
;
$ ^! ] O( i# P2 ]: Y7 x
return tmp;
}
EXPORT_SYMBOL(strcat);
#endif
4 [$ k3 |- P* S, q( W
#ifndef __HAVE_ARCH_STRNCAT
/**
* strncat - Append a length-limited, %NUL-terminated string to another
* @dest: The string to be appended to
* @src: The string to append to it
* @count: The maximum numbers of bytes to copy
*
* Note that in contrast to strncpy, strncat ensures the result is
* terminated.
*/
char * strncat(char *dest, const char *src, size_t count)
{
char *tmp = dest;
7 F" \: R7 k& F3 Z7 p4 N
if (count) {
while (*dest)
dest++;
while ((*dest++ = *src++) != 0) {
if (--count == 0) {
*dest = '/0';
break;
}
}
}
4 }* I7 P2 ?8 ^: i
return tmp;
}
EXPORT_SYMBOL(strncat);
#endif
# C1 C* Z4 j7 P8 }( C9 d m
#ifndef __HAVE_ARCH_STRLCAT
/**
* strlcat - Append a length-limited, %NUL-terminated string to another
* @dest: The string to be appended to
* @src: The string to append to it
* @count: The size of the destination buffer.
*/
size_t strlcat(char *dest, const char *src, size_t count)
{
size_t dsize = strlen(dest);
size_t len = strlen(src);
size_t res = dsize + len;
' q$ y" w* d7 P. D+ Z* b; B- J
/* This would be a bug */
BUG_ON(dsize >= count);
/ E/ ^- T) S7 R j
dest += dsize;
count -= dsize;
if (len >= count)
len = count-1;
memcpy(dest, src, len);
dest[len] = 0;
return res;
}
EXPORT_SYMBOL(strlcat);
#endif
- F- l+ F' b/ o4 C
#ifndef __HAVE_ARCH_STRCMP
/**
* strcmp - Compare two strings
* @cs: One string
* @ct: Another string
*/
#undef strcmp
int strcmp(const char * cs,const char * ct)
{
register signed char __res;
9 D9 `7 n( E. V9 e. C
while (1) {
if ((__res = *cs - *ct++) != 0 || !*cs++)
break;
}
& A4 `0 k- S. h8 f7 I! R/ [2 U6 B
return __res;
}
EXPORT_SYMBOL(strcmp);
#endif
* D4 h9 C5 H o9 a* |/ X v( N
#ifndef __HAVE_ARCH_STRNCMP
/**
* strncmp - Compare two length-limited strings
* @cs: One string
* @ct: Another string
* @count: The maximum number of bytes to compare
*/
int strncmp(const char * cs,const char * ct,size_t count)
{
register signed char __res = 0;
4 w0 r2 v' v1 i% @* g% R; h
while (count) {
if ((__res = *cs - *ct++) != 0 || !*cs++)
break;
count--;
}
0 `! I7 A1 P/ Y) z5 ?
return __res;
}
EXPORT_SYMBOL(strncmp);
#endif
+ V( M4 r3 ], L' c0 p
#ifndef __HAVE_ARCH_STRCHR
/**
* strchr - Find the first occurrence of a character in a string
* @s: The string to be searched
* @c: The character to search for
*/
char * strchr(const char * s, int c)
{
for(; *s != (char) c; ++s)
if (*s == '/0')
return NULL;
return (char *) s;
}
EXPORT_SYMBOL(strchr);
#endif
' o3 F" Y5 b' [
#ifndef __HAVE_ARCH_STRRCHR
/**
* strrchr - Find the last occurrence of a character in a string
* @s: The string to be searched
* @c: The character to search for
*/
char * strrchr(const char * s, int c)
{
const char *p = s + strlen(s);
do {
if (*p == (char)c)
return (char *)p;
} while (--p >= s);
return NULL;
}
EXPORT_SYMBOL(strrchr);
#endif
4 n7 x( h/ n" B5 S/ v
#ifndef __HAVE_ARCH_STRNCHR
/**
* strnchr - Find a character in a length limited string
* @s: The string to be searched
* @count: The number of characters to be searched
* @c: The character to search for
*/
char *strnchr(const char *s, size_t count, int c)
{
for (; count-- && *s != '/0'; ++s)
if (*s == (char) c)
return (char *) s;
return NULL;
}
EXPORT_SYMBOL(strnchr);
#endif
) q* E6 |3 a' x J3 @
#ifndef __HAVE_ARCH_STRLEN
/**
* strlen - Find the length of a string
* @s: The string to be sized
*/
size_t strlen(const char * s)
{
const char *sc;
5 P: m2 [/ j6 K- i9 V- l
for (sc = s; *sc != '/0'; ++sc)
/* nothing */;
return sc - s;
}
EXPORT_SYMBOL(strlen);
#endif
5 B6 e3 p2 L: x8 G P
#ifndef __HAVE_ARCH_STRNLEN
/**
* strnlen - Find the length of a length-limited string
* @s: The string to be sized
* @count: The maximum number of bytes to search
*/
size_t strnlen(const char * s, size_t count)
{
const char *sc;
( R% k3 q- S6 Y% _' y3 D+ N
for (sc = s; count-- && *sc != '/0'; ++sc)
/* nothing */;
return sc - s;
}
EXPORT_SYMBOL(strnlen);
#endif
' B! U1 ]( ~. |+ n& C$ e
#ifndef __HAVE_ARCH_STRSPN
/**
* strspn - Calculate the length of the initial substring of @s which only
* contain letters in @accept
* @s: The string to be searched
* @accept: The string to search for
*/
size_t strspn(const char *s, const char *accept)
{
const char *p;
const char *a;
size_t count = 0;
7 K4 h2 I/ E) M- g* m
for (p = s; *p != '/0'; ++p) {
for (a = accept; *a != '/0'; ++a) {
if (*p == *a)
break;
}
if (*a == '/0')
return count;
++count;
}
w# S* X! u3 I! ]2 O# M, O6 F4 Z
return count;
}
) v, P/ A+ B4 d5 O* {, K
EXPORT_SYMBOL(strspn);
#endif
% f$ \; t5 f! ?1 p
/**
* strcspn - Calculate the length of the initial substring of @s which does
* not contain letters in @reject
* @s: The string to be searched
* @reject: The string to avoid
*/
size_t strcspn(const char *s, const char *reject)
{
const char *p;
const char *r;
size_t count = 0;
7 F+ j) B1 z9 o- U6 L
for (p = s; *p != '/0'; ++p) {
for (r = reject; *r != '/0'; ++r) {
if (*p == *r)
return count;
}
++count;
}
* \6 ?% r; n! _* E# A
return count;
}
EXPORT_SYMBOL(strcspn);
/ d$ m" q# Y, l8 S
#ifndef __HAVE_ARCH_STRPBRK
/**
* strpbrk - Find the first occurrence of a set of characters
* @cs: The string to be searched
* @ct: The characters to search for
*/
char * strpbrk(const char * cs,const char * ct)
{
const char *sc1,*sc2;
4 F! A5 r" R" w
for( sc1 = cs; *sc1 != '/0'; ++sc1) {
for( sc2 = ct; *sc2 != '/0'; ++sc2) {
if (*sc1 == *sc2)
return (char *) sc1;
}
}
return NULL;
}
EXPORT_SYMBOL(strpbrk);
#endif
$ h. [0 F! X2 y* H7 t
#ifndef __HAVE_ARCH_STRSEP
/**
* strsep - Split a string into tokens
* @s: The string to be searched
* @ct: The characters to search for
*
* strsep() updates @s to point after the token, ready for the next call.
*
* It returns empty tokens, too, behaving exactly like the libc function
* of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
* Same semantics, slimmer shape. ;)
*/
char * strsep(char **s, const char *ct)
{
char *sbegin = *s, *end;
$ t* `$ ?7 @7 \) y+ V
if (sbegin == NULL)
return NULL;
; M6 b$ F8 Q4 T( P
end = strpbrk(sbegin, ct);
if (end)
*end++ = '/0';
*s = end;
( S8 P3 n0 {' n/ e
return sbegin;
}
: s! q# Q5 R! d! m1 e3 }
EXPORT_SYMBOL(strsep);
#endif
9 l K/ ?, Z+ V# f: N5 x6 `
#ifndef __HAVE_ARCH_MEMSET
/**
* memset - Fill a region of memory with the given value
* @s: Pointer to the start of the area.
* @c: The byte to fill the area with
* @count: The size of the area.
*
* Do not use memset() to access IO space, use memset_io() instead.
*/
void * memset(void * s,int c,size_t count)
{
char *xs = (char *) s;
1 o" l6 ~. |* X/ U
while (count--)
*xs++ = c;
7 w+ ?/ C- i$ q1 h ^
return s;
}
EXPORT_SYMBOL(memset);
#endif
5 s- t8 x/ [. u( C# J6 e
#ifndef __HAVE_ARCH_MEMCPY
/**
* memcpy - Copy one area of memory to another
* @dest: Where to copy to
* @src: Where to copy from
* @count: The size of the area.
*
* You should not use this function to access IO space, use memcpy_toio()
* or memcpy_fromio() instead.
*/
void * memcpy(void * dest,const void *src,size_t count)
{
char *tmp = (char *) dest, *s = (char *) src;
- x0 l- O P/ o
while (count--)
*tmp++ = *s++;
! c. Q! L3 A: i% c
return dest;
}
EXPORT_SYMBOL(memcpy);
#endif
; U* Y/ x' F8 J
#ifndef __HAVE_ARCH_MEMMOVE
/**
* memmove - Copy one area of memory to another
* @dest: Where to copy to
* @src: Where to copy from
* @count: The size of the area.
*
* Unlike memcpy(), memmove() copes with overlapping areas.
*/
void * memmove(void * dest,const void *src,size_t count)
{
char *tmp, *s;
* p0 Q' F* u% U3 F1 D3 Y: t% M
if (dest <= src) {
tmp = (char *) dest;
s = (char *) src;
while (count--)
*tmp++ = *s++;
}
else {
tmp = (char *) dest + count;
s = (char *) src + count;
while (count--)
*--tmp = *--s;
}
; g. _4 s! z K
return dest;
}
EXPORT_SYMBOL(memmove);
#endif
- K" X5 u( y% ?: W
#ifndef __HAVE_ARCH_MEMCMP
/**
* memcmp - Compare two areas of memory
* @cs: One area of memory
* @ct: Another area of memory
* @count: The size of the area.
*/
#undef memcmp
int memcmp(const void * cs,const void * ct,size_t count)
{
const unsigned char *su1, *su2;
int res = 0;
; S0 s6 M* G: V8 {0 h) {/ ]# a
for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
if ((res = *su1 - *su2) != 0)
break;
return res;
}
EXPORT_SYMBOL(memcmp);
#endif
( x, T _- F2 u5 T* j% i7 r2 } j. M
#ifndef __HAVE_ARCH_MEMSCAN
/**
* memscan - Find a character in an area of memory.
* @addr: The memory area
* @c: The byte to search for
* @size: The size of the area.
*
* returns the address of the first occurrence of @c, or 1 byte past
* the area if @c is not found
*/
void * memscan(void * addr, int c, size_t size)
{
unsigned char * p = (unsigned char *) addr;
5 O& D9 j1 d8 l- x
while (size) {
if (*p == c)
return (void *) p;
p++;
size--;
}
return (void *) p;
}
EXPORT_SYMBOL(memscan);
#endif
2 y+ O) {+ J7 T
#ifndef __HAVE_ARCH_STRSTR
/**
* strstr - Find the first substring in a %NUL terminated string
* @s1: The string to be searched
* @s2: The string to search for
*/
char * strstr(const char * s1,const char * s2)
{
int l1, l2;
7 m; l) h# ^' d$ V
l2 = strlen(s2);
if (!l2)
return (char *) s1;
l1 = strlen(s1);
while (l1 >= l2) {
l1--;
if (!memcmp(s1,s2,l2))
return (char *) s1;
s1++;
}
return NULL;
}
EXPORT_SYMBOL(strstr);
#endif
% N; ]) u6 {) T. h& x
#ifndef __HAVE_ARCH_MEMCHR
/**
* memchr - Find a character in an area of memory.
* @s: The memory area
* @c: The byte to search for
* @n: The size of the area.
*
* returns the address of the first occurrence of @c, or %NULL
* if @c is not found
*/
void *memchr(const void *s, int c, size_t n)
{
const unsigned char *p = s;
while (n-- != 0) {
if ((unsigned char)c == *p++) {
return (void *)(p-1);
}
}
return NULL;
}
EXPORT_SYMBOL(memchr);
#endif
$ y& P. `8 o: E3 ?

作者: Demyar 时间: 2019-9-18 17:29
看看。

作者: wu68aq 时间: 2019-9-29 19:08
好东东必须顶。

欢迎光临 EDA365电子论坛网 (https://bbs.eda365.com/)