// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/lib/string.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <string.h>

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;
}

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;
}

size_t strlen(const char *s)
{
    const char *sc;

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

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

char *strcpy(char *dest, const char *src)
{
    char *tmp = dest;

    while ((*dest++ = *src++) != '\0')
        /* nothing */;
    return tmp;
}

int strcmp(const char *cs, const char *ct)
{
    unsigned char c1, c2;

    while (1) {
        c1 = *cs++;
        c2 = *ct++;
        if (c1 != c2)
            return c1 < c2 ? -1 : 1;
        if (!c1)
            break;
    }
    return 0;
}