/*	SCCS Id: @(#)ovlinit.c	3.2	94/03/20	          */
/* Copyright (c) NetHack PC Development Team 1995                 */
/* NetHack may be freely redistributed.  See license for details. */

#include "hack.h"
#include <dos.h>
#include <stdio.h>


#ifdef _MSC_VER

#define RESERVED_PARAGRAPHS	5120	/* leave 80K for malloc and inits */
 					/* subject to change before release */

/*
 * memavail() Returns the amount of RAM available (in paragraphs which are 16
 *  bytes) - the amount to be reserved for heap allocations.
 *
 */
unsigned memavail(minovl)
unsigned minovl;			/* minimum size of overlay heap */
{
	unsigned available;

    	unsigned farparaavail;
	unsigned tmp;

        /*
         * _dos_allocmem will return the maximum block size available.
         * It uses DOS (int 21h) service 0x48.
         */

	_dos_allocmem(0xFFFF, &farparaavail);
	available = farparaavail - RESERVED_PARAGRAPHS;
	tmp = RESERVED_PARAGRAPHS + minovl;
	if (farparaavail < tmp) {
	   panic("Not enough free RAM to begin a game of NetHack (%ld bytes)",
			(long)((long)tmp * 16L));
	}
	return available;
}
#endif	/*_MSC_VER*/

#ifdef __BORLANDC__

#define RSRVD_MALLOC	65 * 1024L	/* malloc() calls use about 65K    */
#define RSRVD_CRTL	50 * 1024L	/* C runtime library uses 50K      */
#define RSRVD_TOTAL	115 * 1024L	/* reserved for use in malloc()    */
					/* as well as by C runtime library */
					/* routines which allocate memory  */
					/* after this routine runs.        */
#define MIN_OVRBUF	30 * 1024L	/* Overlay buffer gets minimum of  */
#define MAX_OVRBUF	200 * 1024L	/* 30K and maximum of 200K.        */

#define RESIZE_OVL
#ifdef RESIZE_OVL

extern unsigned _ovrbuffer = 0;    /* Use default size initially */
unsigned appFail = 0;              /* Fail flag if not enough RAM */
unsigned memAlloc = 0;
unsigned long ProgramSize;
unsigned long runAlloc;
unsigned far *mem_top;
unsigned total;
signed long tmpbuffer;
int emsstatus;
int xmsstatus;

void NDECL(_resizeOvrBuffer);

void _resizeOvrBuffer()
{
   mem_top = (unsigned far *) MK_FP( _psp, 0x02 );
   total = *mem_top - _psp;

   ProgramSize = * (unsigned far *) MK_FP( _psp - 1, 0x03 );
   tmpbuffer = total - ProgramSize - RSRVD_TOTAL / 16;
   memAlloc = min (MAX_OVRBUF / 16, tmpbuffer);
   if (tmpbuffer >= MIN_OVRBUF / 16)
	_ovrbuffer = memAlloc;
   else {
	_ovrbuffer = 1;
	appFail = 1;
   };


/*
 * Remember, when inside this code, nothing has been setup on
 * the system, so do NOT call any RTL functions for I/O or
 * anything else that might rely on a startup function.  This
 * includes accessing any global objects as their constructors
 * have not been called yet.
 */

}

#pragma startup _resizeOvrBuffer 0      /* Put function in table */

void
startup ()
{
	if (appFail) {
	    printf ("NetHack fits in memory, but it cannot allocate memory");
	    printf (" for the overlay buffer\nand the runtime functions.  ");
	    printf ("Please free up just %ld more bytes.",
			(long)(MIN_OVRBUF - tmpbuffer * 16L));
	    exit (-1);
	} else {

	/* Now try to use expanded memory for the overlay manager */
	/* If that doesn't work, we revert to extended memory */

	emsstatus = _OvrInitEms (0, 0, 0);
#ifdef RECOGNIZE_XMS
	xmsstatus = (emsstatus) ? _OvrInitExt (0, 0) : -1;
#endif

     }
}

void
show_borlandc_stats(win)
winid win;
{
	char buf[BUFSZ];

	putstr(win, 0, "");
	putstr(win, 0, "");
	putstr(win, 0, "Memory usage stats"); putstr(win, 0, "");
	putstr(win, 0, "");
	Sprintf (buf, "Overlay buffer memory allocation: %ld bytes.",
	    memAlloc * 16L); putstr(win, 0, buf);
	Sprintf (buf, "_ovrbuffer = %u.", _ovrbuffer); putstr(win, 0, buf);
	Sprintf (buf, "Startup memory usage: 0x%X", ProgramSize);
	putstr(win, 0, buf);
	runAlloc = * (unsigned far *) MK_FP( _psp - 1, 0x03);
	Sprintf (buf, "Current memory usage: 0x%X", runAlloc);
	putstr(win, 0, buf);
	if (emsstatus) Sprintf (buf, "EMS search failed (%d).", emsstatus);
	else Sprintf (buf, "EMS search successful.");
	putstr(win, 0, buf);
#ifdef RECOGNIZE_XMS
	if (xmsstatus) Sprintf (buf, "XMS search failed (%d).", xmsstatus);
	else Sprintf (buf, "XMS search successful.");
	putstr(win, 0, buf);
#endif


}

#endif  /* #ifdef RESIZE_OVL */
#endif /* #ifdef __BORLANDC__ */

/*ovlinit.c*/
