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/*

 * Copyright (c) 2005 Martin Decky

 * Copyright (c) 2008 Jiri Svoboda

 * 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>

#include <malloc.h>

/** Fill memory block with a constant value. */

void *memset(void *dest, int b, size_t n)

{

    char *pb;

    unsigned long *pw;

    size_t word_size;

    size_t n_words;

    unsigned long pattern;

    size_t i;

    size_t fill;

    /* Fill initial segment. */

    word_size = sizeof(unsigned long);

    fill = word_size - ((uintptr_t) dest & (word_size - 1));

    if (fill > n) fill = n;

    pb = dest;

    i = fill;

    while (i-- != 0)

        *pb++ = b;

    /* Compute remaining size. */

    n -= fill;

    if (n == 0) return dest;

    n_words = n / word_size;

    n = n % word_size;

    pw = (unsigned long *) pb;

    /* Create word-sized pattern for aligned segment. */

    pattern = 0;

    i = word_size;

    while (i-- != 0)

        pattern = (pattern << 8) | (uint8_t) b;

    /* Fill aligned segment. */

    i = n_words;

    while (i-- != 0)

        *pw++ = pattern;

    pb = (char *) pw;

    /* Fill final segment. */

    i = n;

    while (i-- != 0)

        *pb++ = b;

    return dest;

}

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 *) dst;

}

/** Copy memory block. */

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

{

    size_t i;

    size_t mod, fill;

    size_t word_size;

    size_t n_words;

    const unsigned long *srcw;

    unsigned long *dstw;

    const uint8_t *srcb;

    uint8_t *dstb;

    word_size = sizeof(unsigned long);

    /*

     * Are source and destination addresses congruent modulo word_size?

     * If not, use unaligned_memcpy().

     */

    if (((uintptr_t) dst & (word_size - 1)) !=

        ((uintptr_t) src & (word_size - 1)))

        return unaligned_memcpy(dst, src, n);

    /*

     * mod is the address modulo word size. fill is the length of the

     * initial buffer segment before the first word boundary.

     * If the buffer is very short, use unaligned_memcpy(), too.

     */

    mod = (uintptr_t) dst & (word_size - 1);

    fill = word_size - mod;

    if (fill > n) fill = n;

    /* Copy the initial segment. */

    srcb = src;

    dstb = dst;

    i = fill;

    while (i-- != 0)

        *dstb++ = *srcb++;

    /* Compute remaining length. */

    n -= fill;

    if (n == 0) return dst;

    /* Pointers to aligned segment. */

    dstw = (unsigned long *) dstb;

    srcw = (const unsigned long *) srcb;

    n_words = n / word_size;    /* Number of whole words to copy. */

    n -= n_words * word_size;   /* Remaining bytes at the end. */

    /* "Fast" copy. */

    i = n_words;

    while (i-- != 0)

        *dstw++ = *srcw++;

    /*

     * Copy the rest.

     */

    srcb = (const uint8_t *) srcw;

    dstb = (uint8_t *) dstw;

    i = n;

    while (i-- != 0)

        *dstb++ = *srcb++;

    return dst;

}

/** Move memory block with possible overlapping. */

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

{

    uint8_t *dp, *sp;

    /* Nothing to do? */

    if (src == dst)

        return dst;

    /* Non-overlapping? */

    if (dst >= src + n || src >= dst + n) {

        return memcpy(dst, src, n);

    }

    /* Which direction? */

    if (src > dst) {

        /* Forwards. */

        sp = src;

        dp = dst;

        while (n-- != 0)

            *dp++ = *sp++;

    } else {

        /* Backwards. */

        sp = src + (n - 1);

        dp = dst + (n - 1);

        while (n-- != 0)

            *dp-- = *sp--;

    }

    return dst;

}

/** 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);

}

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

{

    int c = 0;

    while (a[c] && b[c] && (!(tolower(a[c]) - tolower(b[c]))))

        c++;

    return (tolower(a[c]) - tolower(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       It's 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;

}

char * strdup(const char *s1)

{

    size_t len = strlen(s1) + 1;

    void *ret = malloc(len);

    if (ret == NULL)

        return (char *) NULL;

    return (char *) memcpy(ret, s1, len);

}

char *strtok(char *s, const char *delim)

{

    static char *next;

    return strtok_r(s, delim, &next);

}

char *strtok_r(char *s, const char *delim, char **next)

{

    char *start, *end;

    if (s == NULL)

        s = *next;

    /* Skip over leading delimiters. */

    while (*s && (strchr(delim, *s) != NULL)) ++s;

    start = s;

    /* Skip over token characters. */

    while (*s && (strchr(delim, *s) == NULL)) ++s;

    end = s;

    *next = (*s ? s + 1 : s);

    if (start == end) {

        return NULL;    /* No more tokens. */

    }

    /* Overwrite delimiter with NULL terminator. */

    *end = '\0';

    return start;

}

/** @}

 */