#include <stddef.h>
#include <stdint.h>

#include "string.h"


int memcmp(const void *s1, const void *s2, size_t n)
{
	unsigned char *a = (unsigned char *) s1;
	unsigned char *b = (unsigned char *) s2;
	for (size_t i=0;i<n;i++)
		if (a[i] != b[i]) return a[i] - b[i];
	return 0;
}

void *memcpy(void *dest, const void *src, size_t n)
{
	unsigned char *d = (unsigned char *) dest;
	unsigned char *s = (unsigned char *) src;
	for (size_t i=0;i<n;i++) d[i] = s[i];
	return dest;
}

void *memmove(void *dest, const void *src, size_t n)
{
	unsigned char *d = (unsigned char *) dest;
	unsigned char *s = (unsigned char *) src;
	if (d < s)
		for (size_t i=0;i<n;i++)
			d[i] = s[i];
	else
		for (size_t i=n;i!=0;i--)
			d[i-1] = s[i-1];
	return dest;
}

void *memset(void *s, int c, size_t n) 
{
	unsigned char *str = (unsigned char *) s;
	for (size_t i=0;i<n;i++) str[i] = c;
	return s;
}

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

// BELOW: YET UNTESTED
char *strcpy(char *dest, const char *src) {
	for (size_t i=0;src[i]!='\0';i++) dest[i] = src[i];
	return dest;
}

char *strncpy(char *dest, const char *src, size_t n) {
	for (size_t i=0;src[i]!='\0'&&i<n;i++) dest[i] = src[i];
	return dest;
}

int strcmp(const char *s1, const char *s2) {
	size_t i;
	for (i = 0;s1[i]!='\0'&&s2[i]!='\0';i++)
		if (s1[i] != s2[i]) break;
	return s1[i] - s2[i];
}

int strncmp(const char *s1, const char *s2, size_t n) {
	size_t i;
	for (i = 0;s1[i]!='\0'&&s2[i]!='\0'&&i<n;i++)
		if (s1[i] != s2[i]) break;
	return s1[i] - s2[i];
}

char *strstr(const char *haystack, const char *needle) {
	int l = strlen(needle);
	for (const char *r=haystack;*r!='\0';r++)
		if (strncmp(r, needle, l) == 0) return (char *) r;
	return NULL;
}

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

	if (c == 0) return (char *) r;
	return NULL;
}

size_t strspn(const char *s, const char *accept) {
	size_t i;
	for (i=0;accept[i]!='\0'&&accept[i]==s[i];i++);
	return i;
}

char *hex(uint32_t n, char *buf)
{
	buf[0] = '0'; buf[1] = 'x';
	for (int i=0;i<8;i++)
	{
		int digit = (n >> (i * 4)) & 0xF;
		if (digit < 10)
			buf[9 - i] = '0' + digit;
		else
			buf[9 - i] = 'A' + (digit - 10);
	}
	return buf;
}

#define R(a, b) (c >= a && c <= b)
bool isupper(char c) {return R('A', 'Z');}
bool islower(char c) {return R('a', 'z');}
bool isalpha(char c) {return isupper(c) || islower(c);}
bool isdigit(char c) {return R('0', '9');}
bool isxdigit(char c) {return isdigit(c) || R('A', 'F') || R('a', 'f');}
bool isalnum(char c) {return isdigit(c) || isalpha(c);}
bool isspace(char c) {return c == ' ' || (unsigned)c-'\t' < 5;}

char toupper(char c) {if (islower(c)) return (c + ('A' - 'a')); else return c;}
char tolower(char c) {if (isupper(c)) return (c - ('A' - 'a')); else return c;}