#include "string.h"
#include <stdbool.h>
#include <stdint.h>

void *memcpy(void *destination, const void *source, size_t num)
{
    if (num > 0)
    {
        const uint8_t *src = (const uint8_t *)source;
        uint8_t *dest = (uint8_t *)destination;
        for (size_t i = 0; i < num; i++)
        {
            dest[i] = src[i];
        }
    }
    return destination;
}

void *memmove(void *destination, const void *source, size_t num)
{
    if (num > 0)
    {
        if (((size_t)destination) < ((size_t)source) || ((size_t)destination) >= (((size_t)source)) + num)
        {
            return memcpy(destination, source, num);
        }
        else if (destination != source)
        {
            size_t i = num - 1;
            const uint8_t *src = (const uint8_t *)source;
            uint8_t *dest = (uint8_t *)destination;
            do
            {
                dest[i] = src[i];
                i--;
            } while (i != 0);
        }
    }
    return destination;
}

int memcmp(const void *ptr1, const void *ptr2, size_t num)
{
    const uint8_t *a = (const uint8_t *)ptr1;
    const uint8_t *b = (const uint8_t *)ptr2;
    for (size_t i = 0; i < num; i++)
    {
        if (a[i] < b[i])
            return -1;
        else if (a[i] > b[i])
            return 1;
    }
    return 0;
}

void *memset(void *ptr, int value, size_t num)
{
    uint8_t *dest = (uint8_t *)ptr;
    uint8_t v = (uint8_t)value;
    for (size_t i = 0; i < num; i++)
    {
        dest[i] = v;
    }
    return ptr;
}

int strlen(const char *str)
{
    int i = 0;
    while (str[i] != '\0')
    {
        i++;
    }
    return i;
}

char *strcpy(char *destination, const char *source)
{
    int sourceLen = strlen(source);
    if ((destination <= source) || (destination > (source + sourceLen)))
    {
        char *d = destination;
        const char *s = source;
        while (true)
        {
            *d = *s;
            if (*s == '\0')
            {
                break;
            }
            else
            {
                s++;
                d++;
            }
        }
    }
    else
    {
        char *d = destination + sourceLen;
        const char *s = source + sourceLen;
        do
        {
            *d = *s;
            d--;
            s--;
        } while (d > destination);
    }
    return destination;
}