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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.

 */

/** @addtogroup libc

 * @{

 */

/** @file

 */

#include <string.h>

#include <unistd.h>

#include <ctype.h>

#include <limits.h>

#include <align.h>

#include <sys/types.h>

/* Dummy implementation of mem/ functions */

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

{

    char *os = s;

    while (n--)

        *(os++) = c;

    return s;

}

struct along {

    unsigned long n;

} __attribute__ ((packed));

static void *unaligned_memcpy(void *dst, const void *src, size_t n)

{

    int i, j;

    struct along *adst = dst;

    const struct along *asrc = src;

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

        adst[i].n = asrc[i].n;

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

{

    int i, j;

    if (((long) dst & (sizeof(long) - 1)) || ((long) src & (sizeof(long) - 1)))

        return unaligned_memcpy(dst, src, n);

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

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

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

    return (char *) src;

}

/** Compare two memory areas.

 *

 * @param s1    Pointer to the first area to compare.

 * @param s2    Pointer to the second area to compare.

 * @param len   Size of the first area in bytes. Both areas must have the same

 *      length.

 * @return  If len is 0, return zero. If the areas match, return zero.

 *      Otherwise return non-zero.

 */

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

{

    for (; len && *s1++ == *s2++; len--)

        ;

    return len;

}

/** 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]);

}

int strncmp(const char *a, const char *b, size_t n)

{

    size_t c = 0;

    while (c < n && a[c] && b[c] && (!(a[c] - b[c])))

        c++;

    return ( c < n ? a[c] - b[c] : 0);

}

/** 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)

{

    char *orig = dest;

    while ((*(dest++) = *(src++)))

        ;

    return orig;

}

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

{

    char *orig = dest;

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

        ;

    return orig;

}

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

{

    char *orig = dest;

    while (*dest++)

        ;

    --dest;

    while ((*dest++ = *src++))

        ;

    return orig;

}

/** @}

 */