#include <string.h>

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

void*
memset(void* bufptr, int value, size_t size)
{
        unsigned char* buf = (unsigned char*) bufptr;
        for (size_t i = 0; i < size; i++) {
                buf[i] = (unsigned char) value;
        }
        return bufptr;
}

void*
memmove(void* dstptr, const void* srcptr, size_t size)
{
	unsigned char* dst = (unsigned char*) dstptr;
	const unsigned char* src = (const unsigned char*) srcptr;
	if (dst < src) {
		for (size_t i = 0; i < size; i++)
			dst[i] = src[i];
	} else {
		for (size_t i = size; i != 0; i--)
			dst[i-1] = src[i-1];
	}
	return dstptr;
}

void*
memcpy(void* restrict dstptr, const void* restrict srcptr, size_t size)
{
	unsigned char* dst = (unsigned char*) dstptr;
	const unsigned char* src = (const unsigned char*) srcptr;
	for (size_t i = 0; i < size; i++) {
		dst[i] = src[i];
        }
	return dstptr;
}

int
memcmp(const void* aptr, const void* bptr, size_t size)
{
	const unsigned char* a = (const unsigned char*) aptr;
	const unsigned char* b = (const unsigned char*) bptr;
	for (size_t i = 0; i < size; i++) {
		if (a[i] < b[i]) {
			return -1;
                } else if (b[i] < a[i]) {
			return 1;
                }
	}
	return 0;
}