#include "seg.h"
#include "mem.h"
#include <core/sys.h>
#include <lib/cpp.h>

segment::segment() {
	mappings = 0;
}
segment::~segment() {
}

/*	Call this function when mapping a segment to a page directory.
	Calls the appropriate map method and updates the segment's and pagedir's information. */
segment_map *segment::map(page_directory *pagedir, size_t offset) {
	segment_map *sm = i_map(pagedir, offset);
	if (sm == 0) return 0;
	mappings++;

	sm->seg = this;
	sm->pagedir = pagedir;
	sm->next = pagedir->mappedSegs;
	pagedir->mappedSegs = sm;
	return sm;
}

/*	Call this function when unmapping a segment from a page directory.
	The segment will automatically be deleted if it is not mapped.
	Calls the appropriate unmap method and updates the segment's and pagedir's information. */
void segment::unmap(segment_map *map) {
	ASSERT(this == map->seg);
	i_unmap(map);
	if (map->pagedir->mappedSegs == map) {
		map->pagedir->mappedSegs = map->next;
	} else {
		segment_map *m = map->pagedir->mappedSegs;
		while (m->next != 0 && m->next != map) m = m->next;
		if (m->next == map) m->next = map->next;
	}
	delete map;
	mappings--;
	if (mappings == 0) {
		delete this;
	}
}

// ************************************   SIMPLESEG stuff *************
 

/*	Call this when creating a simpleseg.
	Creates the simpleseg structure and the segment structure and fills them up. */
simpleseg::simpleseg(size_t s, size_t l, int w) : segment() {
	writable = w;
	start = s;
	len = l;
}

simpleseg::~simpleseg() {
}

/*	For internal use only. Called when a simpleseg is mapped to a pagedirectory. */
segment_map* simpleseg::i_map(page_directory* pagedir, size_t offset) {
	segment_map *sm = new segment_map();
	sm->start = start;
	sm->len = len;
	return sm;
}

/*	For internal use only. Called when a simpleseg is unmapped.
	Frees all the allocated pages. */
void simpleseg::i_unmap(segment_map* sm) {
	size_t i;
	for (i = sm->start; i < sm->start + sm->len; i += 0x1000) {
		page_unmapFree(pagedir_getPage(sm->pagedir, i, 0));
	}
}

/*	For internal use only. Handles a page fault. Can allocate and map a frame if necessary. */
int simpleseg::handle_fault(segment_map* sm, size_t addr, int write) {
	ASSERT(sm->seg == this);

	if (write && !writable) return 1;
	addr &= 0xFFFFF000;
	page *p = pagedir_getPage(sm->pagedir, addr, 1);
	if (p->frame != 0) return 1;
	page_map(p, frame_alloc(), 1, writable);
	return 0;
}

/*	Call this to resize a simpleseg. Ajusts the size and frees pages if the new size is smaller.*/
int simpleseg::resize(segment_map *map, size_t nlen) {
	ASSERT(this == map->seg);

	size_t i;

	if (map == 0) return -1;

	if (nlen & 0xFFF) nlen = (nlen & 0xFFFFF000) + 0x1000;
	if (nlen < map->len) {
		for (i = map->start + nlen; i < map->start + map->len; i += 0x1000) {
			page_unmapFree(pagedir_getPage(map->pagedir, i, 0));
		}
		map->len = nlen;
		len = nlen;
	} else if (nlen > map->len) {
		map->len = nlen;
		len = nlen;
	}
	return 0;
}