#include <stddef.h>
#include <stdint.h>
#include <lib/libc.h>

int toupper(int c) {
    if (c >= 'a' && c <= 'z') {
        return c - 0x20;
    }
    return c;
}

int tolower(int c) {
    if (c >= 'A' && c <= 'Z') {
        return c + 0x20;
    }
    return c;
}

char *strcpy(char *dest, const char *src) {
    size_t i;

    for (i = 0; src[i]; i++)
        dest[i] = src[i];

    dest[i] = 0;

    return dest;
}

char *strncpy(char *dest, const char *src, size_t n) {
    size_t i;

    for (i = 0; i < n && src[i]; i++)
        dest[i] = src[i];
    for ( ; i < n; i++)
        dest[i] = 0;

    return dest;
}

int strcmp(const char *s1, const char *s2) {
    for (size_t i = 0; ; i++) {
        char c1 = s1[i], c2 = s2[i];
        if (c1 != c2)
            return c1 < c2 ? -1 : 1;
        if (!c1)
            return 0;
    }
}

int strncmp(const char *s1, const char *s2, size_t n) {
    for (size_t i = 0; i < n; i++) {
        char c1 = s1[i], c2 = s2[i];
        if (c1 != c2)
            return c1 < c2 ? -1 : 1;
        if (!c1)
            return 0;
    }

    return 0;
}

size_t strlen(const char *str) {
    size_t len;

    for (len = 0; str[len]; len++);

    return len;
}