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/*

 * Copyright (C) 2005 Martin Decky

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include <string.h>

#include <unistd.h>

#include <ctype.h>

#include <limits.h>

/* Dummy implementation of mem/ functions */

void * memset(void *s, int c, size_t n)

{

	char *os = s;

	while (n--)

		*(os++) = c;

	return s;

}

void * memcpy(void *dst, const void *src, size_t n)

{

	int i, j;

	for (i = 0; i < n/sizeof(unsigned long); i++)

		((unsigned long *) dst)[i] = ((unsigned long *) src)[i];

	for (j = 0; j < n%sizeof(unsigned long); j++)

		((unsigned char *)(((unsigned long *) dst) + i))[j] = ((unsigned char *)(((unsigned long *) src) + i))[j];

	return (char *)src;

}

void * memmove(void *dst, const void *src, size_t n)

{

	int i, j;

	if (src > dst)

		return memcpy(dst, src, n);

	for (j = (n%sizeof(unsigned long))-1; j >= 0; j--)

		((unsigned char *)(((unsigned long *) dst) + i))[j] = ((unsigned char *)(((unsigned long *) src) + i))[j];

	for (i = n/sizeof(unsigned long)-1; i >=0 ; i--)

		((unsigned long *) dst)[i] = ((unsigned long *) src)[i];

	return (char *)src;

}

/** Count the number of characters in the string, not including terminating 0.

 * @param str string

 * @return number of characters in string.

 */

size_t strlen(const char *str) 

{

	size_t counter = 0;

	while (str[counter] != 0) {

		counter++;

	}

	return counter;

}

int strcmp(const char *a,const char *b)

{

	int c=0;

	while(a[c]&&b[c]&&(!(a[c]-b[c]))) c++;

	return a[c]-b[c];

}

/** Return pointer to the first occurence of character c in string

 * @param str scanned string 

 * @param c searched character (taken as one byte)

 * @return pointer to the matched character or NULL if it is not found in given string.

 */

char *strchr(const char *str, int c)

{

	while (*str != '\0') {

		if (*str == (char)c)

			return (char *)str;

		str++;

	}

	return NULL;

}

/** Return pointer to the last occurence of character c in string

 * @param str scanned string 

 * @param c searched character (taken as one byte)

 * @return pointer to the matched character or NULL if it is not found in given string.

 */

char *strrchr(const char *str, int c)

{

	char *retval = NULL;

	while (*str != '\0') {

		if (*str == (char)c)

			retval = (char *)str;

		str++;

	}

	return (char *)retval;

}

/** Convert string to a number. 

 * Core of strtol and strtoul functions.

 * @param nptr pointer to string

 * @param endptr if not NULL, function stores here pointer to the first invalid character

 * @param base zero or number between 2 and 36 inclusive

 * @param sgn its set to 1 if minus found

 * @return result of conversion.

 */

static unsigned long _strtoul(const char *nptr, char **endptr, int base, char *sgn)

{

	unsigned char c;

	unsigned long result = 0;

	unsigned long a, b;

	const char *str = nptr;

	const char *tmpptr;

	while (isspace(*str))

		str++;

	if (*str == '-') {

		*sgn = 1;

		++str;

	} else if (*str == '+')

		++str;

	if (base) {

		if ((base == 1) || (base > 36)) {

			/* FIXME: set errno to EINVAL */

			return 0;

		}

		if ((base == 16) && (*str == '0') && ((str[1] == 'x') || (str[1] == 'X'))) {

			str += 2;

		}

	} else {

		base = 10;

		if (*str == '0') {

			base = 8;

			if ((str[1] == 'X') || (str[1] == 'x'))  {

				base = 16;

				str += 2;

			}

		} 

	}

	tmpptr = str;

	while (*str) {

		c = *str;

		c = ( c >= 'a'? c-'a'+10:(c >= 'A'?c-'A'+10:(c <= '9'?c-'0':0xff)));

		if (c > base) {

			break;

		}

		a = (result & 0xff) * base + c;

		b = (result >> 8) * base + (a >> 8);

		if (b > (ULONG_MAX >> 8)) {

			/* overflow */

			/* FIXME: errno = ERANGE*/

			return ULONG_MAX;

		}

		result = (b << 8) + (a & 0xff);

		++str;

	}

	if (str == tmpptr) {

		/* no number was found => first invalid character is the first character of the string */

		/* FIXME: set errno to EINVAL */

		str = nptr;

		result = 0;

	}

	if (endptr)

		*endptr = (char *)str;

	if (nptr == str) { 

		/*FIXME: errno = EINVAL*/

		return 0;

	}

	return result;

}

/** Convert initial part of string to long int according to given base.

 * The number may begin with an arbitrary number of whitespaces followed by optional sign (`+' or `-').

 * If the base is 0 or 16, the prefix `0x' may be inserted and the number will be taken as hexadecimal one.

 * If the base is 0 and the number begin with a zero, number will be taken as octal one (as with base 8).

 * Otherwise the base 0 is taken as decimal.

 * @param nptr pointer to string

 * @param endptr if not NULL, function stores here pointer to the first invalid character

 * @param base zero or number between 2 and 36 inclusive

 * @return result of conversion.

 */

long int strtol(const char *nptr, char **endptr, int base)

{

	char sgn = 0;

	unsigned long number = 0;

	number = _strtoul(nptr, endptr, base, &sgn);

	if (number > LONG_MAX) {

		if ((sgn) && (number == (unsigned long)(LONG_MAX) + 1)) {

			/* FIXME: set 0 to errno */

			return number;		

		}

		/* FIXME: set ERANGE to errno */

		return (sgn?LONG_MIN:LONG_MAX);	

	}

	return (sgn?-number:number);

}

/** Convert initial part of string to unsigned long according to given base.

 * The number may begin with an arbitrary number of whitespaces followed by optional sign (`+' or `-').

 * If the base is 0 or 16, the prefix `0x' may be inserted and the number will be taken as hexadecimal one.

 * If the base is 0 and the number begin with a zero, number will be taken as octal one (as with base 8).

 * Otherwise the base 0 is taken as decimal.

 * @param nptr pointer to string

 * @param endptr if not NULL, function stores here pointer to the first invalid character

 * @param base zero or number between 2 and 36 inclusive

 * @return result of conversion.

 */

unsigned long strtoul(const char *nptr, char **endptr, int base)

{

	char sgn = 0;

	unsigned long number = 0;

	number = _strtoul(nptr, endptr, base, &sgn);

	return (sgn?-number:number);

}

char *strcpy(char *dest, const char *src)

{

	while (*(dest++) = *(src++))

		;

}

char *strncpy(char *dest, const char *src, size_t n)

{

	while ((*(dest++) = *(src++)) && --n)

		;

}