/*
   *  linux/lib/string.c
   *
   *  Copyright (C) 1991, 1992  Linus Torvalds
   */
  
  /*
   * 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 <ioe@informatik.tu-chemnitz.de>
   * -  Added strsep() which will replace strtok() soon (because strsep() is
   *    reentrant and should be faster). Use only strsep() in new code, please.
   */
  
  #include <linux/types.h>
  #include <linux/string.h>
  #include <linux/ctype.h>
  #include <malloc.h>

  /**

   * strncasecmp - Case insensitive, length-limited string comparison

   * @s1: One string
   * @s2: The other string
   * @len: the maximum number of characters to compare
   */

  int strncasecmp(const char *s1, const char *s2, size_t len)

  {
  	/* Yes, Virginia, it had better be unsigned */
  	unsigned char c1, c2;
  
  	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;
  }

  
  /**
   * strcasecmp - Case insensitive string comparison
   * @s1: One string
   * @s2: The other string
   */
  int strcasecmp(const char *s1, const char *s2)
  {
  	return strncasecmp(s1, s2, -1U);
  }

  
  char * ___strtok;
  
  #ifndef __HAVE_ARCH_STRCPY
  /**
   * strcpy - Copy a %NUL terminated string
   * @dest: Where to copy the string to
   * @src: Where to copy the string from
   */
  char * strcpy(char * dest,const char *src)
  {
  	char *tmp = dest;
  
  	while ((*dest++ = *src++) != '\0')
  		/* nothing */;
  	return tmp;
  }
  #endif
  
  #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
   *
   * Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
   * However, the result is not %NUL-terminated if the source exceeds
   * @count bytes.
   */
  char * strncpy(char * dest,const char *src,size_t count)
  {
  	char *tmp = dest;
  
  	while (count-- && (*dest++ = *src++) != '\0')
  		/* nothing */;
  
  	return tmp;
  }
  #endif

  #ifndef __HAVE_ARCH_STRLCPY
  /**
   * strlcpy - Copy a C-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);
  
  	if (size) {
  		size_t len = (ret >= size) ? size - 1 : ret;
  		memcpy(dest, src, len);
  		dest[len] = '\0';
  	}
  	return ret;
  }
  #endif

  #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
   */
  char * strcat(char * dest, const char * src)
  {
  	char *tmp = dest;
  
  	while (*dest)
  		dest++;
  	while ((*dest++ = *src++) != '\0')
  		;
  
  	return tmp;
  }
  #endif
  
  #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;
  
  	if (count) {
  		while (*dest)
  			dest++;
  		while ((*dest++ = *src++)) {
  			if (--count == 0) {
  				*dest = '\0';
  				break;
  			}
  		}
  	}
  
  	return tmp;
  }
  #endif
  
  #ifndef __HAVE_ARCH_STRCMP
  /**
   * strcmp - Compare two strings
   * @cs: One string
   * @ct: Another string
   */
  int strcmp(const char * cs,const char * ct)
  {
  	register signed char __res;
  
  	while (1) {
  		if ((__res = *cs - *ct++) != 0 || !*cs++)
  			break;
  	}
  
  	return __res;
  }
  #endif
  
  #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;
  
  	while (count) {
  		if ((__res = *cs - *ct++) != 0 || !*cs++)
  			break;
  		count--;
  	}
  
  	return __res;
  }
  #endif
  
  #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;
  }
  #endif

  const char *strchrnul(const char *s, int c)
  {
  	for (; *s != (char)c; ++s)
  		if (*s == '\0')
  			break;
  	return s;
  }

  #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;
  }
  #endif
  
  #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;
  
  	for (sc = s; *sc != '\0'; ++sc)
  		/* nothing */;
  	return sc - s;
  }
  #endif
  
  #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;
  
  	for (sc = s; count-- && *sc != '\0'; ++sc)
  		/* nothing */;
  	return sc - s;
  }
  #endif

  #ifndef __HAVE_ARCH_STRCSPN
  /**
   * 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;
  
  	for (p = s; *p != '\0'; ++p) {
  		for (r = reject; *r != '\0'; ++r) {
  			if (*p == *r)
  				return count;
  		}
  		++count;
  	}
  	return count;
  }
  #endif

  #ifndef __HAVE_ARCH_STRDUP
  char * strdup(const char *s)
  {
  	char *new;
  
  	if ((s == NULL)	||
  	    ((new = malloc (strlen(s) + 1)) == NULL) ) {
  		return NULL;
  	}
  
  	strcpy (new, s);
  	return new;
  }
  #endif
  
  #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;
  
  	for (p = s; *p != '\0'; ++p) {
  		for (a = accept; *a != '\0'; ++a) {
  			if (*p == *a)
  				break;
  		}
  		if (*a == '\0')
  			return count;
  		++count;
  	}
  
  	return count;
  }
  #endif
  
  #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;
  
  	for( sc1 = cs; *sc1 != '\0'; ++sc1) {
  		for( sc2 = ct; *sc2 != '\0'; ++sc2) {
  			if (*sc1 == *sc2)
  				return (char *) sc1;
  		}
  	}
  	return NULL;
  }
  #endif
  
  #ifndef __HAVE_ARCH_STRTOK
  /**
   * strtok - Split a string into tokens
   * @s: The string to be searched
   * @ct: The characters to search for
   *
   * WARNING: strtok is deprecated, use strsep instead.
   */
  char * strtok(char * s,const char * ct)
  {
  	char *sbegin, *send;
  
  	sbegin  = s ? s : ___strtok;
  	if (!sbegin) {
  		return NULL;
  	}
  	sbegin += strspn(sbegin,ct);
  	if (*sbegin == '\0') {
  		___strtok = NULL;
  		return( NULL );
  	}
  	send = strpbrk( sbegin, ct);
  	if (send && *send != '\0')
  		*send++ = '\0';
  	___strtok = send;
  	return (sbegin);
  }
  #endif
  
  #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;
  
  	if (sbegin == NULL)
  		return NULL;
  
  	end = strpbrk(sbegin, ct);
  	if (end)
  		*end++ = '\0';
  	*s = end;
  
  	return sbegin;
  }
  #endif

  #ifndef __HAVE_ARCH_STRSWAB
  /**
   * strswab - swap adjacent even and odd bytes in %NUL-terminated string
   * s: address of the string
   *
   * returns the address of the swapped string or NULL on error. If
   * string length is odd, last byte is untouched.
   */
  char *strswab(const char *s)
  {

  	char *p, *q;

  
  	if ((NULL == s) || ('\0' == *s)) {
  		return (NULL);
  	}

  	for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {

  		char  tmp;

  
  		tmp = *p;
  		*p  = *q;
  		*q  = tmp;

  	}
  
  	return (char *) s;
  }
  #endif

  #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)
  {

  	unsigned long *sl = (unsigned long *) s;

  	char *s8;

  
  #if !CONFIG_IS_ENABLED(TINY_MEMSET)
  	unsigned long cl = 0;

  	int i;
  
  	/* do it one word at a time (32 bits or 64 bits) while possible */
  	if ( ((ulong)s & (sizeof(*sl) - 1)) == 0) {
  		for (i = 0; i < sizeof(*sl); i++) {
  			cl <<= 8;
  			cl |= c & 0xff;
  		}
  		while (count >= sizeof(*sl)) {
  			*sl++ = cl;
  			count -= sizeof(*sl);
  		}
  	}

  #endif	/* fill 8 bits at a time */

  	s8 = (char *)sl;

  	while (count--)

  		*s8++ = c;

  
  	return s;
  }
  #endif

  #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)

  {

  	unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
  	char *d8, *s8;

  	if (src == dest)
  		return dest;

  	/* while all data is aligned (common case), copy a word at a time */
  	if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) {
  		while (count >= sizeof(*dl)) {
  			*dl++ = *sl++;
  			count -= sizeof(*dl);
  		}
  	}
  	/* copy the reset one byte at a time */
  	d8 = (char *)dl;
  	s8 = (char *)sl;

  	while (count--)

  		*d8++ = *s8++;

  
  	return dest;
  }
  #endif
  
  #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;
  
  	if (dest <= src) {

  		memcpy(dest, src, count);
  	} else {

  		tmp = (char *) dest + count;
  		s = (char *) src + count;
  		while (count--)
  			*--tmp = *--s;
  		}
  
  	return dest;
  }
  #endif
  
  #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.
   */
  int memcmp(const void * cs,const void * ct,size_t count)
  {
  	const unsigned char *su1, *su2;
  	int res = 0;
  
  	for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
  		if ((res = *su1 - *su2) != 0)
  			break;
  	return res;
  }
  #endif
  
  #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;
  
  	while (size) {
  		if (*p == c)
  			return (void *) p;
  		p++;
  		size--;
  	}

  	return (void *) p;

  }
  #endif
  
  #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;
  
  	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;
  }
  #endif
  
  #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;
  }
  
  #endif

  #ifndef __HAVE_ARCH_MEMCHR_INV
  static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
  {
  	while (bytes) {
  		if (*start != value)
  			return (void *)start;
  		start++;
  		bytes--;
  	}
  	return NULL;
  }
  /**
   * memchr_inv - Find an unmatching character in an area of memory.
   * @start: The memory area
   * @c: Find a character other than c
   * @bytes: The size of the area.
   *
   * returns the address of the first character other than @c, or %NULL
   * if the whole buffer contains just @c.
   */
  void *memchr_inv(const void *start, int c, size_t bytes)
  {
  	u8 value = c;
  	u64 value64;
  	unsigned int words, prefix;
  
  	if (bytes <= 16)
  		return check_bytes8(start, value, bytes);
  
  	value64 = value;
  	value64 |= value64 << 8;
  	value64 |= value64 << 16;
  	value64 |= value64 << 32;
  
  	prefix = (unsigned long)start % 8;
  	if (prefix) {
  		u8 *r;
  
  		prefix = 8 - prefix;
  		r = check_bytes8(start, value, prefix);
  		if (r)
  			return r;
  		start += prefix;
  		bytes -= prefix;
  	}
  
  	words = bytes / 8;
  
  	while (words) {
  		if (*(u64 *)start != value64)
  			return check_bytes8(start, value, 8);
  		start += 8;
  		words--;
  	}
  
  	return check_bytes8(start, value, bytes % 8);
  }
  #endif