/*
 * Copyright (c) 1992, 1993, 1996
 *	Berkeley Software Design, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Berkeley Software
 *	Design, Inc.
 *
 * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	BSDI mem.c,v 2.2 1996/04/08 19:32:57 bostic Exp
 */

#include <stdio.h>
#include "doscmd.h"

#define	Mark(x)	(*(char *) (x))
#define Owner(x) (*(u_short *) ((char *)(x)+1))
#define Size(x) (*(u_short *) ((char *)(x)+3))
#define Next(x) ((char *)(x) + (Size(x)+1)*16)

static char *next_p = (char *)0;
static char *end_p  = (char *)0xB0000L;

char *core_alloc(int *size)
{
	char *ret;
	if (*size) {
		if (*size & 0xfff) {
			*size = (*size & ~0xfff) + 0x1000;
		}
	} else {
		*size = end_p - next_p;
	}

	if (next_p + *size > end_p) {
		return NULL;
	}

	ret = next_p;
	next_p += *size;
	return ret;
}

void
mem_free_owner(int owner)
{
	char *mp;

	debug(D_MEMORY, "    : freeow(%04x)\n", owner);

	for (mp = dosmem; ; mp = Next(mp)) {
		if (Owner(mp) == owner)
			Owner(mp) = 0;

		if (Mark(mp) != 'M')
			break;
	}
}

void
mem_print()
{
	char *mp;

	for (mp = dosmem; ; mp = Next(mp)) {
		debug(D_ALWAYS, "%05x: mark %c owner %04x size %04x\n",
		    mp, Mark(mp), Owner(mp), Size(mp));

		if (Mark(mp) != 'M')
			break;
	}
}

void	
mem_change_owner(int addr, int owner)
{
	char *mp;

    	debug(D_MEMORY, "%04x: owner (%04x)\n", addr, owner);
	addr <<= 4;

	for (mp = dosmem; ; mp = Next(mp)) {
		if ((int)(mp + 16) == addr)
			goto found;

		if (Mark(mp) != 'M')
			break;
	}

	debug(D_ALWAYS, "%05x: illegal block in change owner\n", addr);
	mem_print();
	return;

found:
	Owner(mp) = owner;
}

void
mem_init()
{
	int base, avail_memory;

	base = 0x600;
	core_alloc(&base);

	avail_memory = MAX_AVAIL_SEG * 16 - base;
	dosmem = core_alloc(&avail_memory);

	if (!dosmem || dosmem != (char *)base)
		fatal("internal memory error\n");

	dosmem_size = avail_memory / 16;

	debug(D_MEMORY, "dosmem = 0x%x base = 0x%x avail = 0x%x (%dK)\n",
			dosmem, base, dosmem_size, avail_memory / 1024);

	Mark(dosmem) = 'Z';
	Owner(dosmem) = 0;
	Size(dosmem) = dosmem_size - 1;
}

void
mem_unsplit(char *mp, int size)
{
	char *nmp;

	while (Mark(mp) == 'M' && Size(mp) < size) {
		nmp = Next(mp);

		if (Owner(nmp) != 0)
			break;

		Size(mp) += Size(nmp) + 1;
		Mark(mp) = Mark(nmp);
	}
}

void
mem_split(char *mp, int size)
{
	char *nmp;
	int rest;

	rest = Size(mp) - size;
	Size(mp) = size;
	nmp = Next(mp);
	Mark(nmp) = Mark(mp);
	Mark(mp) = 'M';
	Owner(nmp) = 0;
	Size(nmp) = rest - 1;
}

int
mem_alloc(int size, int owner, int *biggestp)
{
	char *mp;
	int biggest;

	biggest = 0;
	for (mp = dosmem; ; mp = Next(mp)) {
		if (Owner(mp) == 0) {
			if (Size(mp) < size)
				mem_unsplit(mp, size);
			if (Size(mp) >= size)
				goto got;

			if (Size(mp) > biggest)
				biggest = Size(mp);
		}

		if (Mark(mp) != 'M')
			break;
	}

	debug(D_MEMORY, "%04x: alloc(%04x, owner %04x) failed -> %d\n",
			0, size, owner, biggest);

	if (biggestp)
		*biggestp = biggest;
	return 0;

got:
	if (Size(mp) > size)
		mem_split(mp, size);
	Owner(mp) = owner;
	debug(D_MEMORY, "%04x: alloc(%04x, owner %04x)\n",
			(int)mp/16 + 1, size, owner);

	if (biggestp)
		*biggestp = size;
	return (int)mp/16 + 1;
}

int
mem_adjust(int addr, int size, int *availp)
{
	char *mp;
	int delta, nxtsiz;

	debug(D_MEMORY, "%04x: adjust(%05x)\n", addr, size);
	addr <<= 4;

	for (mp = dosmem; ; mp = Next(mp)) {
		if ((int)(mp + 16) == addr)
			goto found;

		if (Mark(mp) != 'M')
			break;
	}

	debug(D_ALWAYS, "%05x: illegal block in adjust\n", addr);
	mem_print();
	return -2;

found:
	if (Size(mp) < size)
		mem_unsplit(mp, size);
	if (Size(mp) >= size)
		goto got;

	debug(D_MEMORY, "%04x: adjust(%04x) failed -> %d\n",
			(int)mp/16 + 1, size, Size(mp));

	if (availp)
		*availp = Size(mp);
	return -1;

got:
	if (Size(mp) > size)
		mem_split(mp, size);
	debug(D_MEMORY, "%04x: adjust(%04x)\n",
			(int)mp/16 + 1, size);

	if (availp)
		*availp = size;
	return 0;
}

		

#ifdef	MEM_TEST
mem_check ()
{
	struct mem_block *mp;
	for (mp = mem_blocks.next; mp != &mem_blocks; mp = mp->next) {
		if (mp->addr + mp->size != mp->next->addr)
			break;
		if (mp->inuse && mp->size == 0)
			return (-1);
	}

	if (mp->next != &mem_blocks)
		return (-1);
	return (0);
}

mem_print ()
{
	struct mem_block *mp;

	for (mp = mem_blocks.next; mp != &mem_blocks; mp = mp->next) {
		printf ("%8x %8x %9d %c ",
			mp, mp->addr, mp->size, mp->inuse ? 'u' : 'f');
		if (mp->addr + mp->size != mp->next->addr)
			printf ("*");
		printf ("\n");
	}
}

char *blocks[10];

main ()
{
	int i;
	int n;
	int newsize;

	mem_init (0, 300);

	for (i = 0; i < 100000; i++) {
		n = random () % 10;

		if (blocks[n]) {
			newsize = random () % 20;
			if ((newsize & 1) == 0)
				newsize = 0;
			
			if (0)
				printf ("adjust %d %x %d\n",
					n, blocks[n], newsize);
			mem_adjust (blocks[n], newsize, NULL);
			if (newsize == 0)
				blocks[n] = NULL;
		} else {
			while ((newsize = random () % 20) == 0)
				;
			if (0)
				printf ("alloc %d %d\n", n, newsize);
			blocks[n] = mem_alloc (newsize, NULL);
		}
		if (mem_check () < 0) {
			printf ("==== %d\n", i);
			mem_print ();
		}
	}

	mem_print ();
}
#endif /* MEM_TEST */