#include <std.h>

char* itoa(int n, char *a)
{
	char *ret = a;
	if(n < 0) {
		*a++ = '-';
		n *= -1;
	}
	char *b = a;
	if(!n) *b++ = '0';
	for(; n; b++) {
		*b = n%10 + '0';
		n = n/10;
	}
	*b-- = '\0';
	for(; a < b; a++, b--) { //reverse
		char temp = *b;
		*b = *a;
		*a = temp;
	}
	return ret;
}

char* ftoa(double x, char *a, unsigned int prec)
{
	char *ret = a;
	int n = (int) x; //integer part
	double d = x - (double) n; //fractional part;
	itoa(n, a);
	if(prec) { //only do the decimal part if decimal parts were asked for
		while(*a && *++a); //get to the null character from itoa
		int i; //counter variable for the for loop
		*a++ = '.'; //put the decimal in place
		for(i = 0; i < prec; i++) {
			d = d*10; //the integer part is the decimal digit
			*a++ = ((int) d) + '0'; //add the integer part of d to the string
			d -= (int) d; //chop off the integer part
		} a--; //move back to the last digit
		while(*a != '.') {
			if(*a == '0') {
				a--;
				continue;
			} else if(*a > '0' && *a <= '9') {
				a++;
				break;
			}
		}
		*a = '\0';
	}
	return ret;
}

int atoi(char *a)
{
	short neg = 0;
	int n = 0;
	if(*a == '-') {
		neg = 1;
		a++;
	} else if(*a == '+') a++;
	while(*a >= '0' && *a <= '9')
		n = n*10 + (*a++ - '0');
	if(neg) n *= -1;
	return n;
}

double atof(char *a)
{
	int n = atoi(a);
	double x = 0;
	double dec = .1;
	while(*a != '.') {
		if(!(*a >= '0' && *a <= '9')) return n;
		a++;
	} a++; //a will be immediately after the decimal point
	while(*a >= '0' && *a <= '9') { //goes through the decimal part
		x += (*a - '0')*dec;
		dec *= .1;
		a++;
	}
	return n + x;
}

void sPrint(char *a)
{
	char *b = a;
	while(*b && *++b);
	do {
		putline(a, (b - a > CON_LEN)?CON_LEN:(b - a));
		a += CON_LEN;
	} while(a < b);
}

int strcmp(const char *a, const char *b)
{
	while(1) {
		if(*a - *b) return *a - *b;
		if(*a == '\0') return 0;
		a++;
		b++;
	}
	return -1;
}

char* sGet(char *a, unsigned int n)
{
	int length = getline(a, n);
	a[(length < n)?length:n - 1] = '\0';
	return a;
}

int arrayLookup(char *text, const char array[][10], int last)
{
	int i;
	for(i = 0; i < last; i++)
		if(!strcmp(array[i], text)) return i;
	return last;
}

char* append(char *dest, char *src)
{
	char *ret = dest;
	while(*dest&& *++dest); //get to null in first string
	while((*dest++ = *src++));
	return ret;
}

static Header base;
static Header *allocp = NULL; //the location of the last known free block

void malloc_init(size_t memSize)
{
	allocp = &base;
	allocp->size = 0;
	allocp->next = (void*)HEAP_START;
	allocp->next->next = &base;
	allocp->next->size = memSize/sizeof(blockUnit);
	if((sizeof(blockUnit)%sizeof(u64))) {
		sPrint("WARNING: MEMORY NOT 8-BYTE ALIGNED\n");
		char foo[40];
		sPrint(append("MEMORY BLOCK SIZE IS: ", append(itoa(sizeof(Header), foo), "\n")));
	}
}

void* malloc(size_t size)
{
	if(allocp == NULL) return NULL;
	size_t nUnits = ((size + sizeof(Header)) + sizeof(blockUnit) - 1)/sizeof(blockUnit);
	Header *prev = allocp;
	Header *cur, *temp;
	for(cur = prev->next;; prev = cur, cur = cur->next) {
		if(cur->size >= nUnits) {
			if(cur->size == nUnits) {
				prev->next = cur->next;
			} else {
				temp = cur + nUnits; //This requires sizeof(blockUnit) == sizeof(Header).  TODO fix
				temp->size = cur->size - nUnits;
				temp->next = cur->next;
				prev->next = temp;
				cur->size = nUnits;
			}
			allocp = prev;
			return (void*)(cur + 1);
		} else if(cur == allocp) { //We went back to the start...
			return NULL;
		}
	}
}

void free(void *ptr)
{
	Header *toFree = (Header *)ptr - 1;
	Header *scan;
	for(scan = allocp; !(toFree > scan && toFree < scan->next); scan = scan->next)
		if(scan->next < scan && (toFree > scan || toFree < scan->next)) break;
	toFree->next = scan->next;
	scan->next = toFree;
	if(scan + toFree->size == toFree) {
		scan->size += toFree->size;
		scan->next = toFree->next;
		toFree = scan;
	}
	if(toFree + toFree->size == toFree->next) {
		toFree->size += toFree->next->size;
		toFree->next = toFree->next->next;
	}
}