/* string.c — Freestanding libc string functions for KHY OS * @pattern Strategy
 */

#include "string.h"

void *memset(void *dest, int val, size_t len) {
    uint8_t *p = (uint8_t *)dest;
    while (len--)
        *p++ = (uint8_t)val;
    return dest;
}

void *memcpy(void *dest, const void *src, size_t len) {
    uint8_t *d = (uint8_t *)dest;
    const uint8_t *s = (const uint8_t *)src;
    while (len--)
        *d++ = *s++;
    return dest;
}

void *memmove(void *dest, const void *src, size_t len) {
    uint8_t *d = (uint8_t *)dest;
    const uint8_t *s = (const uint8_t *)src;
    if (d < s) {
        while (len--)
            *d++ = *s++;
    } else {
        d += len;
        s += len;
        while (len--)
            *--d = *--s;
    }
    return dest;
}

int memcmp(const void *s1, const void *s2, size_t len) {
    const uint8_t *a = (const uint8_t *)s1;
    const uint8_t *b = (const uint8_t *)s2;
    while (len--) {
        if (*a != *b)
            return *a - *b;
        a++;
        b++;
    }
    return 0;
}

size_t strlen(const char *s) {
    size_t len = 0;
    while (s[len])
        len++;
    return len;
}

int strcmp(const char *s1, const char *s2) {
    while (*s1 && *s1 == *s2) {
        s1++;
        s2++;
    }
    return (unsigned char)*s1 - (unsigned char)*s2;
}

int strncmp(const char *s1, const char *s2, size_t n) {
    while (n && *s1 && *s1 == *s2) {
        s1++;
        s2++;
        n--;
    }
    if (n == 0)
        return 0;
    return (unsigned char)*s1 - (unsigned char)*s2;
}