/*
Copyright (C) 1996-1997 Id Software, Inc.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/
// zone.c - memory management

#include "common.h"

void Cache_FreeLow (int new_low_hunk);
void Cache_FreeHigh (int new_high_hunk);


//============================================================================

#define	HUNK_SENTINEL	0x1df001ed

typedef struct
{
	int		sentinel;
	int		size;		// including sizeof(hunk_t), -1 = not allocated
	char	name[8];
} hunk_t;

byte	*hunk_base;
int		hunk_size;

int		hunk_low_used;
int		hunk_high_used;

qbool	hunk_tempactive;
int		hunk_tempmark;

/*
==============
Hunk_Check

Run consistency and sentinel trashing checks
==============
*/
void Hunk_Check (void)
{
	hunk_t	*h;
	
	for (h = (hunk_t *)hunk_base ; (byte *)h != hunk_base + hunk_low_used ; )
	{
		if (h->sentinel != HUNK_SENTINEL)
			Sys_Error ("Hunk_Check: trashed sentinel");
		if (h->size < 16 || h->size + (byte *)h - hunk_base > hunk_size)
			Sys_Error ("Hunk_Check: bad size");
		h = (hunk_t *)((byte *)h+h->size);
	}
}

/*
==============
Hunk_Print

If "all" is specified, every single allocation is printed.
Otherwise, allocations with the same name will be totaled up before printing.
==============
*/
void Hunk_Print (qbool all)
{
	hunk_t	*h, *next, *endlow, *starthigh, *endhigh;
	int		count, sum;
	int		totalblocks;
	char	name[9];

	name[8] = 0;
	count = 0;
	sum = 0;
	totalblocks = 0;
	
	h = (hunk_t *)hunk_base;
	endlow = (hunk_t *)(hunk_base + hunk_low_used);
	starthigh = (hunk_t *)(hunk_base + hunk_size - hunk_high_used);
	endhigh = (hunk_t *)(hunk_base + hunk_size);

	Com_Printf ("          :%8i total hunk size\n", hunk_size);
	Com_Printf ("-------------------------\n");

	while (1)
	{
	//
	// skip to the high hunk if done with low hunk
	//
		if ( h == endlow )
		{
			Com_Printf ("-------------------------\n");
			Com_Printf ("          :%8i REMAINING\n", hunk_size - hunk_low_used - hunk_high_used);
			Com_Printf ("-------------------------\n");
			h = starthigh;
		}
		
	//
	// if totally done, break
	//
		if ( h == endhigh )
			break;

	//
	// run consistency checks
	//
		if (h->sentinel != HUNK_SENTINEL)
			Sys_Error ("Hunk_Check: trashed sentinel");
		if (h->size < 16 || h->size + (byte *)h - hunk_base > hunk_size)
			Sys_Error ("Hunk_Check: bad size");
			
		next = (hunk_t *)((byte *)h+h->size);
		count++;
		totalblocks++;
		sum += h->size;

	//
	// print the single block
	//
		memcpy (name, h->name, 8);
		if (all)
			Com_Printf ("%8p :%8i %8s\n",h, h->size, name);
			
	//
	// print the total
	//
		if (next == endlow || next == endhigh || 
		strncmp (h->name, next->name, 8) )
		{
			if (!all)
				Com_Printf ("          :%8i %8s (TOTAL)\n",sum, name);
			count = 0;
			sum = 0;
		}

		h = next;
	}

	Com_Printf ("-------------------------\n");
	Com_Printf ("%8i total blocks\n", totalblocks);
	
}

/*
===================
Hunk_AllocName
===================
*/
void *Hunk_AllocName (int size, char *name)
{
	hunk_t	*h;
	
#ifdef PARANOID
	Hunk_Check ();
#endif

	if (size < 0)
		Sys_Error ("Hunk_Alloc: bad size: %i", size);
		
	size = sizeof(hunk_t) + ((size+15)&~15);
	
	if (hunk_size - hunk_low_used - hunk_high_used < size)
//		Sys_Error ("Hunk_Alloc: failed on %i bytes",size);
	  	Sys_Error ("Not enough RAM allocated.  Try starting using \"-mem 16\" (or more) on the command line.");

	h = (hunk_t *)(hunk_base + hunk_low_used);
	hunk_low_used += size;

	Cache_FreeLow (hunk_low_used);

	memset (h, 0, size);
	
	h->size = size;
	h->sentinel = HUNK_SENTINEL;
	strncpy (h->name, name, 8);
	
	return (void *)(h+1);
}

/*
===================
Hunk_Alloc
===================
*/
void *Hunk_Alloc (int size)
{
	return Hunk_AllocName (size, "unknown");
}

int	Hunk_LowMark (void)
{
	return hunk_low_used;
}

void Hunk_FreeToLowMark (int mark)
{
	if (mark < 0 || mark > hunk_low_used)
		Sys_Error ("Hunk_FreeToLowMark: bad mark %i", mark);
	memset (hunk_base + mark, 0, hunk_low_used - mark);
	hunk_low_used = mark;
}

int	Hunk_HighMark (void)
{
	if (hunk_tempactive)
	{
		hunk_tempactive = false;
		Hunk_FreeToHighMark (hunk_tempmark);
	}

	return hunk_high_used;
}

void Hunk_FreeToHighMark (int mark)
{
	if (hunk_tempactive)
	{
		hunk_tempactive = false;
		Hunk_FreeToHighMark (hunk_tempmark);
	}
	if (mark < 0 || mark > hunk_high_used)
		Sys_Error ("Hunk_FreeToHighMark: bad mark %i", mark);
	memset (hunk_base + hunk_size - hunk_high_used, 0, hunk_high_used - mark);
	hunk_high_used = mark;
}


/*
===================
Hunk_HighAllocName
===================
*/
void *Hunk_HighAllocName (int size, char *name)
{
	hunk_t	*h;

	if (size < 0)
		Sys_Error ("Hunk_HighAllocName: bad size: %i", size);

	if (hunk_tempactive)
	{
		Hunk_FreeToHighMark (hunk_tempmark);
		hunk_tempactive = false;
	}

#ifdef PARANOID
	Hunk_Check ();
#endif

	size = sizeof(hunk_t) + ((size+15)&~15);

	if (hunk_size - hunk_low_used - hunk_high_used < size)
	{
		Com_Printf ("Hunk_HighAlloc: failed on %i bytes\n",size);
		return NULL;
	}

	hunk_high_used += size;
	Cache_FreeHigh (hunk_high_used);

	h = (hunk_t *)(hunk_base + hunk_size - hunk_high_used);

	memset (h, 0, size);
	h->size = size;
	h->sentinel = HUNK_SENTINEL;
	strncpy (h->name, name, 8);

	return (void *)(h+1);
}


/*
=================
Hunk_TempAlloc

Return space from the top of the hunk
=================
*/
void *Hunk_TempAlloc (int size)
{
	void	*buf;

	size = (size+15)&~15;
	
	if (hunk_tempactive)
	{
		Hunk_FreeToHighMark (hunk_tempmark);
		hunk_tempactive = false;
	}
	
	hunk_tempmark = Hunk_HighMark ();

	buf = Hunk_HighAllocName (size, "temp");

	hunk_tempactive = true;

	return buf;
}

/*
===============================================================================

CACHE MEMORY

===============================================================================
*/

typedef struct cache_system_s
{
	int						size;		// including this header
	cache_user_t			*user;
	char					name[16];
	struct cache_system_s	*prev, *next;
	struct cache_system_s	*lru_prev, *lru_next;	// for LRU flushing	
} cache_system_t;

cache_system_t *Cache_TryAlloc (int size, qbool nobottom);

cache_system_t	cache_head;

/*
===========
Cache_Move
===========
*/
void Cache_Move ( cache_system_t *c)
{
	cache_system_t		*new;

// we are clearing up space at the bottom, so only allocate it late
	new = Cache_TryAlloc (c->size, true);
	if (new)
	{
//		Com_Printf ("cache_move ok\n");

		memcpy ( new+1, c+1, c->size - sizeof(cache_system_t) );
		new->user = c->user;
		memcpy (new->name, c->name, sizeof(new->name));
		Cache_Free (c->user);
		new->user->data = (void *)(new+1);
	}
	else
	{
//		Com_Printf ("cache_move failed\n");

		Cache_Free (c->user);		// tough luck...
	}
}

/*
============
Cache_FreeLow

Throw things out until the hunk can be expanded to the given point
============
*/
void Cache_FreeLow (int new_low_hunk)
{
	cache_system_t	*c;
	
	while (1)
	{
		c = cache_head.next;
		if (c == &cache_head)
			return;		// nothing in cache at all
		if ((byte *)c >= hunk_base + new_low_hunk)
			return;		// there is space to grow the hunk
		Cache_Move ( c );	// reclaim the space
	}
}

/*
============
Cache_FreeHigh

Throw things out until the hunk can be expanded to the given point
============
*/
void Cache_FreeHigh (int new_high_hunk)
{
	cache_system_t	*c, *prev;
	
	prev = NULL;
	while (1)
	{
		c = cache_head.prev;
		if (c == &cache_head)
			return;		// nothing in cache at all
		if ( (byte *)c + c->size <= hunk_base + hunk_size - new_high_hunk)
			return;		// there is space to grow the hunk
		if (c == prev)
			Cache_Free (c->user);	// didn't move out of the way
		else
		{
			Cache_Move (c);	// try to move it
			prev = c;
		}
	}
}

void Cache_UnlinkLRU (cache_system_t *cs)
{
	if (!cs->lru_next || !cs->lru_prev)
		Sys_Error ("Cache_UnlinkLRU: NULL link");

	cs->lru_next->lru_prev = cs->lru_prev;
	cs->lru_prev->lru_next = cs->lru_next;
	
	cs->lru_prev = cs->lru_next = NULL;
}

void Cache_MakeLRU (cache_system_t *cs)
{
	if (cs->lru_next || cs->lru_prev)
		Sys_Error ("Cache_MakeLRU: active link");

	cache_head.lru_next->lru_prev = cs;
	cs->lru_next = cache_head.lru_next;
	cs->lru_prev = &cache_head;
	cache_head.lru_next = cs;
}

/*
============
Cache_TryAlloc

Looks for a free block of memory between the high and low hunk marks
Size should already include the header and padding
============
*/
cache_system_t *Cache_TryAlloc (int size, qbool nobottom)
{
	cache_system_t	*cs, *new;
	
// is the cache completely empty?

	if (!nobottom && cache_head.prev == &cache_head)
	{
		if (hunk_size - hunk_high_used - hunk_low_used < size)
			Sys_Error ("Cache_TryAlloc: %i is greater then free hunk", size);

		new = (cache_system_t *) (hunk_base + hunk_low_used);
		memset (new, 0, sizeof(*new));
		new->size = size;

		cache_head.prev = cache_head.next = new;
		new->prev = new->next = &cache_head;
		
		Cache_MakeLRU (new);
		return new;
	}
	
// search from the bottom up for space

	new = (cache_system_t *) (hunk_base + hunk_low_used);
	cs = cache_head.next;
	
	do
	{
		if (!nobottom || cs != cache_head.next)
		{
			if ( (byte *)cs - (byte *)new >= size)
			{	// found space
				memset (new, 0, sizeof(*new));
				new->size = size;
				
				new->next = cs;
				new->prev = cs->prev;
				cs->prev->next = new;
				cs->prev = new;
				
				Cache_MakeLRU (new);
	
				return new;
			}
		}

	// continue looking		
		new = (cache_system_t *)((byte *)cs + cs->size);
		cs = cs->next;

	} while (cs != &cache_head);
	
// try to allocate one at the very end
	if ( hunk_base + hunk_size - hunk_high_used - (byte *)new >= size)
	{
		memset (new, 0, sizeof(*new));
		new->size = size;
		
		new->next = &cache_head;
		new->prev = cache_head.prev;
		cache_head.prev->next = new;
		cache_head.prev = new;
		
		Cache_MakeLRU (new);

		return new;
	}
	
	return NULL;		// couldn't allocate
}

/*
============
Cache_Flush

Throw everything out, so new data will be demand cached
============
*/
void Cache_Flush (void)
{
	while (cache_head.next != &cache_head)
		Cache_Free ( cache_head.next->user );	// reclaim the space
}


/*
============
Cache_Print

============
*/
void Cache_Print (void)
{
	cache_system_t	*cd;

	for (cd = cache_head.next ; cd != &cache_head ; cd = cd->next)
	{
		Com_Printf ("%8i : %s\n", cd->size, cd->name);
	}
}

/*
============
Cache_Report

============
*/
void Cache_Report (void)
{
	Com_DPrintf ("%4.1f megabyte data cache\n", (hunk_size - hunk_high_used - hunk_low_used) / (float)(1024*1024) );
}

/*
============
Cache_Compact

============
*/
void Cache_Compact (void)
{
}

/*
============
Cache_Init

============
*/
void Cache_Init (void)
{
	cache_head.next = cache_head.prev = &cache_head;
	cache_head.lru_next = cache_head.lru_prev = &cache_head;

	Cmd_AddCommand ("flush", Cache_Flush);
}

/*
==============
Cache_Free

Frees the memory and removes it from the LRU list
==============
*/
void Cache_Free (cache_user_t *c)
{
	cache_system_t	*cs;

	if (!c->data)
		Sys_Error ("Cache_Free: not allocated");

	cs = ((cache_system_t *)c->data) - 1;

	cs->prev->next = cs->next;
	cs->next->prev = cs->prev;
	cs->next = cs->prev = NULL;

	c->data = NULL;

	Cache_UnlinkLRU (cs);
}



/*
==============
Cache_Check
==============
*/
void *Cache_Check (cache_user_t *c)
{
	cache_system_t	*cs;

	if (!c->data)
		return NULL;

	cs = ((cache_system_t *)c->data) - 1;

// move to head of LRU
	Cache_UnlinkLRU (cs);
	Cache_MakeLRU (cs);
	
	return c->data;
}


/*
==============
Cache_Alloc
==============
*/
void *Cache_Alloc (cache_user_t *c, int size, char *name)
{
	cache_system_t	*cs;

	if (c->data)
		Sys_Error ("Cache_Alloc: already allocated");
	
	if (size <= 0)
		Sys_Error ("Cache_Alloc: size %i", size);

	size = (size + sizeof(cache_system_t) + 15) & ~15;

// find memory for it	
	while (1)
	{
		cs = Cache_TryAlloc (size, false);
		if (cs)
		{
			strncpy (cs->name, name, sizeof(cs->name)-1);
			c->data = (void *)(cs+1);
			cs->user = c;
			break;
		}
	
	// free the least recently used cahedat
		if (cache_head.lru_prev == &cache_head)
			Sys_Error ("Cache_Alloc: out of memory");
													// not enough memory at all
		Cache_Free ( cache_head.lru_prev->user );
	} 
	
	return Cache_Check (c);
}

//============================================================================


/*
========================
Memory_Init
========================
*/
void Memory_Init (void *buf, int size)
{
	hunk_base = buf;
	hunk_size = size;
	hunk_low_used = 0;
	hunk_high_used = 0;
	
	Cache_Init ();
}

