/* File: main-ibm.c */

/*
 * Copyright (c) 1997 Ben Harrison, and others
 *
 * This software may be copied and distributed for educational, research,
 * and not for profit purposes provided that this copyright and statement
 * are included in all such copies.
 */

/* Purpose: Visual Display Support for "term.c", for the IBM */


/*
 * Original code by "Billy Tanksley (wtanksle@ucsd.edu)"
 * Use "Makefile.ibm" to compile Angband using this file.
 *
 * Support for DJGPP v2 by "Scott Egashira (egashira@u.washington.edu)"
 *
 * Extensive modifications by "Ben Harrison (benh@phial.com)",
 * including "collation" of the Watcom C/C++ and DOS-286 patches.
 *
 * Watcom C/C++ changes by "David Boeren (akemi@netcom.com)"
 * Use "Makefile.wat" to compile this file with Watcom C/C++, and
 * be sure to define "USE_IBM" and "USE_WAT".
 *
 * DOS-286 (conio.h) changes by (Roland Jay Roberts (jay@map.com)
 * Use "Makefile.286" (not ready) to compile this file for DOS-286,
 * and be sure to define "USE_IBM", "USE_WAT", and "USE_286".  Also,
 * depending on your compiler, you may need to define "USE_CONIO".
 *
 * True color palette support by "Mike Marcelais (michmarc@microsoft.com)",
 * with interface to the "color_table" array by Ben Harrison.
 *
 * Both "shift" keys are treated as "identical", and all the modifier keys
 * (control, shift, alt) are ignored when used with "normal" keys, unless
 * they modify the underlying "ascii" value of the key.  You must use the
 * new "user pref files" to be able to interact with the keypad and such.
 *
 * The "lib/user/pref-ibm.prf" file contains macro definitions and possible
 * alternative color set definitions.  The "lib/user/font-ibm.prf" contains
 * attr/char mappings for walls and floors and such.
 *
 * Note the "Term_user_ibm()" function hook, which could allow the user
 * to interact with the "main-ibm.c" visual system.  Currently this hook
 * is unused, but, for example, it could allow the user to toggle "sound"
 * or "graphics" modes, or to select the number of screen rows, with the
 * extra screen rows being used for the mirror window.
 */


#include "angband.h"


#ifdef USE_IBM


/*
 * Use a "virtual" screen to "buffer" screen writes.
 */
#define USE_VIRTUAL


#include <bios.h>
#include <dos.h>

#ifdef USE_WAT

# include <conio.h>

# ifdef USE_CONIO
# else /* USE_CONIO */

#  include <graph.h>

#  define bioskey(C)	_bios_keybrd(C)

# endif /* USE_CONIO */

# ifndef USE_286
#  define int86(a,b,c)	int386(a,b,c)
# endif

# define inportb(x)	inp(x)
# define outportb(x,y)	outp(x,y)

#else /* USE_WAT */

# if __DJGPP__ > 1

# include <pc.h>
# include <osfcn.h>

# else /* __DJGPP__ > 1 */
#  ifdef __DJGPP__
#   error "Upgrade to version 2.0 of DJGPP"
#  endif /* __DJGPP__ */
# endif /* __DJGPP__ > 1 */

#endif /* USE_WAT */


#ifdef USE_CONIO

# include <conio.h>

/*
 * Hack -- write directly to video card
 */
extern int directvideo = 1;

/*
 * Hack -- no virtual screen
 */
# undef USE_VIRTUAL

#endif /* USE_CONIO */


/*
 * Keypress input modifier flags (hard-coded by DOS)
 */
#define K_RSHIFT	0	/* Right shift key down */
#define K_LSHIFT	1	/* Left shift key down */
#define K_CTRL		2	/* Ctrl key down */
#define K_ALT		3	/* Alt key down */
#define K_SCROLL	4	/* Scroll lock on */
#define K_NUM		5	/* Num lock on */
#define K_CAPS		6	/* Caps lock on */
#define K_INSERT	7	/* Insert on */


/*
 * Foreground color bits (hard-coded by DOS)
 */
#define VID_BLACK	0x00
#define VID_BLUE	0x01
#define VID_GREEN	0x02
#define VID_CYAN	0x03
#define VID_RED		0x04
#define VID_MAGENTA	0x05
#define VID_YELLOW	0x06
#define VID_WHITE	0x07

/*
 * Bright text (hard-coded by DOS)
 */
#define VID_BRIGHT	0x08

/*
 * Background color bits (hard-coded by DOS)
 */
#define VUD_BLACK	0x00
#define VUD_BLUE	0x10
#define VUD_GREEN	0x20
#define VUD_CYAN	0x30
#define VUD_RED		0x40
#define VUD_MAGENTA	0x50
#define VUD_YELLOW	0x60
#define VUD_WHITE	0x70

/*
 * Blinking text (hard-coded by DOS)
 */
#define VUD_BRIGHT	0x80


/*
 * Screen Size
 */
static int rows = 25;
static int cols = 80;


/*
 * Physical Screen
 */
#ifdef USE_286
# define PhysicalScreen ((byte *)MK_FP(0xB800,0x0000))
#else
# define PhysicalScreen ((byte *)(0xB800 << 4))
#endif


#ifdef USE_VIRTUAL

/*
 * Virtual Screen Contents
 */
static byte *VirtualScreen;

#else

/*
 * Physical screen access
 */
#define VirtualScreen PhysicalScreen

#endif


/*
 * Hack -- the cursor "visibility"
 */
static int saved_cur_v;
static int saved_cur_high;
static int saved_cur_low;


#ifdef USE_CONIO
#else /* USE_CONIO */

/*
 * This array is used for "wiping" the screen
 */
static byte wiper[160];

#endif /* USE_CONIO */


/*
 * The main screen (currently the only screen)
 */
static term term_screen_body;


/*
 * Choose between the "complex" and "simple" color methods
 */
static byte use_color_complex = FALSE;


/*
 * The "complex" color set
 */
static long ibm_color_complex[16];


/*
 * The "simple" color set
 *
 * This table is used by the "color" code to instantiate the "approximate"
 * Angband colors using the only colors available on crappy monitors.
 *
 * The entries below are taken from the "color bits" defined above.
 *
 * Note that values from 16 to 255 are extremely ugly.
 *
 * The values below came from various sources, if you do not like them,
 * get a better monitor, or edit "pref-ibm.prf" to use different codes.
 *
 * Note that many of the choices below suck, but so do crappy monitors.
 */
static byte ibm_color_simple[16] =
{
	VID_BLACK,			/* Dark */
	VID_WHITE,			/* White */
	VID_CYAN,			/* Slate XXX */
	VID_RED | VID_BRIGHT,	/* Orange XXX */
	VID_RED,			/* Red */
	VID_GREEN,			/* Green */
	VID_BLUE,			/* Blue */
	VID_YELLOW,			/* Umber XXX */
	VID_BLACK | VID_BRIGHT,	/* Light Dark */
	VID_CYAN | VID_BRIGHT,	/* Light Slate XXX */
	VID_MAGENTA,		/* Violet */
	VID_YELLOW | VID_BRIGHT,	/* Yellow */
	VID_MAGENTA | VID_BRIGHT,	/* Light Red XXX */
	VID_GREEN | VID_BRIGHT,	/* Light Green */
	VID_BLUE | VID_BRIGHT,	/* Light Blue */
	VID_YELLOW			/* Light Umber XXX */
};



/*
 * Activate the "ibm_color_complex" palette information.
 *
 * Code by Mike Marcelais, with help from "The programmer's guide
 * to the EGA and VGA video cards" [Farraro].
 *
 * On VGA cards, colors go through a double-indirection when looking
 * up the `real' color when in 16 color mode.  The color value in the
 * attribute is looked up in the EGA color registers.  Then that value
 * is looked up in the VGA color registers.  Then the color is displayed.
 * This is done for compatability.  However, the EGA registers are
 * initialized by default to 0..5, 14, 7, 38..3F and not 0..F which means
 * that unless these are reset, the VGA setpalette function will not
 * update the correct palette register!
 *
 * DJGPP's GrSetColor() does _not_ set the EGA palette list, only the
 * VGA color list.
 *
 * Note that the "traditional" method, using "int86(0x10)", is very slow
 * when called in protected mode, so we use a faster method using video
 * ports instead.
 *
 * On Watcom machines, we could simply use the special "_remapallpalette()"
 * function, which not only sets both palette lists (see below) but also
 * checks for legality of the monitor mode, but, if we are doing bitmapped
 * graphics, that function forgets to set the EGA registers for some reason.
 */
static void activate_color_complex(void)
{
	int i;
	printf("%c%c%c%c",8,8,8,8);

#if 1

	/* Edit the EGA palette */
	inportb(0x3da);

	/* Edit the colors */
	for (i = 0; i < 16; i++)
	{
		/* Set color "i" */
		outportb(0x3c0, i);

		/* To value "i" */
		outportb(0x3c0, i);
	};

	/* Use that EGA palette */
	outportb(0x3c0, 0x20);

	/* Edit VGA palette, starting at color zero */
	outportb(0x3c8, 0);

	/* Send the colors */
	for (i = 0; i < 16; i++)
	{
		/* Send the red, green, blue components */
		outportb(0x3c9, ((ibm_color_complex[i]) & 0xFF));
		outportb(0x3c9, ((ibm_color_complex[i] >> 8) & 0xFF));
		outportb(0x3c9, ((ibm_color_complex[i] >> 16) & 0xFF));
	}

#else /* 1 */

	/* Set the colors */
	for (i = 0; i < 16; i++)
	{
		union REGS r;

		/* Set EGA color */
		r.h.ah = 0x10;
		r.h.al = 0x00;

		/* Set color "i" */
		r.h.bl = i;

		/* To value "i" */
		r.h.bh = i;

		/* Do it */
		int86(0x10, &r, &r);

		/* Set VGA color */
		r.h.ah = 0x10;
		r.h.al = 0x10;

		/* Set color "i" */
		r.h.bh = 0x00;
		r.h.bl = i;

		/* Use this "green" value */
		r.h.ch = ((ibm_color_complex[i] >> 8) & 0xFF);

		/* Use this "blue" value */
		r.h.cl = ((ibm_color_complex[i] >> 16) & 0xFF);

		/* Use this "red" value */
		r.h.dh = ((ibm_color_complex[i]) & 0xFF);

		/* Do it */
		int86(0x10, &r, &r);
	}

#endif /* 1 */

};


/*
 * Note the use of "(x >> 2)" to convert an 8 bit value to a 6 bit value
 * without losing much precision.
 */
static int Term_xtra_ibm_react(void)
{
	int i;

	/* Complex method */
	if (use_color_complex)
	{
		long rv, gv, bv, code;

		bool change = FALSE;

		/* Save the default colors */
		for (i = 0; i < 16; i++)
		{
			/* Extract desired values */
			rv = angband_color_table[i][1] >> 2;
			gv = angband_color_table[i][2] >> 2;
			bv = angband_color_table[i][3] >> 2;

			/* Extract a full color code */
			code = ((rv) | (gv << 8) | (bv << 16));

			/* Activate changes */
			if (ibm_color_complex[i] != code)
			{
				/* Note the change */
				change = TRUE;

				/* Apply the desired color */
				ibm_color_complex[i] = code;
			}
		}

		/* Activate the palette if needed */
		if (change) activate_color_complex();
	}

	/* Simple method */
	else
	{
		/* Save the default colors */
		for (i = 0; i < 16; i++)
		{
			/* Simply accept the desired colors */
			ibm_color_simple[i] = angband_color_table[i][0];
		}
	}

	/* Success */
	return (0);
}



/*
 * Hack -- set the cursor "visibility"
 */
static void curs_set(int v)
{
	/* If needed */
	if (saved_cur_v != v)
	{
		union REGS r;

		/* Set cursor */
		r.h.ah = 1;

		/* Visible */
		if (v)
		{
			/* Use the saved values */
			r.h.ch = saved_cur_high;
			r.h.cl = saved_cur_low;
		}

		/* Invisible */
		else
		{
			/* Make it invisible */
			r.h.ch = 0x20;
			r.h.cl = 0x00;
		}

		/* Make the call */
		int86(0x10, &r, &r);

		/* Save the cursor state */
		saved_cur_v = v;
	}
}



/*
 * Process an event (check for a keypress)
 *
 * The keypress processing code is often the most system dependant part
 * of Angband, since sometimes even the choice of compiler is important.
 *
 * For the IBM, we divide all keypresses into two catagories, first, the
 * "normal" keys, including all keys required to play Angband, and second,
 * the "special" keys, such as keypad keys, function keys, and various keys
 * used in combination with various modifier keys.
 *
 * To simplify this file, we use Angband's "macro processing" ability, in
 * combination with a specialized "pref-ibm.prf" file, to handle most of the
 * "special" keys, instead of attempting to fully analyze them here.  This
 * file only has to determine when a "special" key has been pressed, and
 * translate it into a simple string which signals the use of a "special"
 * key, the set of modifiers used, if any, and the hardware scan code of
 * the actual key which was pressed.  To simplify life for the user, we
 * treat both "shift" keys as identical modifiers.
 *
 * The final encoding is "^_MMMxSS\r", where "MMM" encodes the modifiers
 * ("C" for control, "S" for shift, "A" for alt, or any ordered combination),
 * and "SS" encodes the keypress (as the two "digit" hexidecimal encoding of
 * the scan code of the key that was pressed), and the "^_" and "x" and "\r"
 * delimit the encoding for recognition by the macro processing code.
 *
 * Some important facts about scan codes follow.  All "normal" keys use
 * scan codes from 1-58.  The "function" keys use 59-68 (and 133-134).
 * The "keypad" keys use 69-83.  Escape uses 1.  Enter uses 28.  Control
 * uses 29.  Left Shift uses 42.  Right Shift uses 54.  PrtScrn uses 55.
 * Alt uses 56.  Space uses 57.  CapsLock uses 58.  NumLock uses 69.
 * ScrollLock uses 70.  The "keypad" keys which use scan codes 71-83
 * are ordered KP7,KP8,KP9,KP-,KP4,KP5,KP6,KP+,KP1,KP2,KP3,INS,DEL.
 *
 * Using "bioskey(0x10)" instead of "bioskey(0)" apparently provides more
 * information, including better access to the keypad keys in combination
 * with various modifiers, but only works on "PC's after 6/1/86", and there
 * is no way to determine if the function is provided on a machine.  I have
 * been told that without it you cannot detect, for example, control-left.
 * The basic scan code + ascii value pairs returned by the keypad follow,
 * with values in parentheses only available to "bioskey(0x10)".
 *
 *         /      *      -      +      1      2      3      4
 * Norm:  352f   372a   4a2d   4e2b   4f00   5000   5100   4b00
 * Shft:  352f   372a   4a2d   4e2b   4f31   5032   5133   4b34
 * Ctrl: (9500) (9600) (8e00) (9000)  7500  (9100)  7600   7300
 *
 *         5      6      7      8      9      0      .     Enter
 * Norm: (4c00)  4d00   4700   4800   4900   5200   5300  (e00d)
 * Shft:  4c35   4d36   4737   4838   4939   5230   532e  (e00d)
 * Ctrl: (8f00)  7400   7700  (8d00)  8400  (9200) (9300) (e00a)
 *
 * See "pref-ibm.prf" for the "standard" macros for various keys.
 *
 * Certain "bizarre" keypad keys (such as "enter") return a "scan code"
 * of "0xE0", and a "usable" ascii value.  These keys should be treated
 * like the normal keys, see below.  XXX XXX XXX Note that these "special"
 * keys could be prefixed with an optional "ctrl-^" which would allow them
 * to be used in macros without hurting their use in normal situations.
 */
static errr Term_xtra_ibm_event(int v)
{
	int i, k, s;

	bool mc = FALSE;
	bool ms = FALSE;
	bool ma = FALSE;


	/* Hack -- Check for a keypress */
	if (!v && !bioskey(1)) return (1);

	/* Wait for a keypress */
	k = bioskey(0x10);

	/* Access the "modifiers" */
	i = bioskey(2);

	/* Extract the "scan code" */
	s = ((k >> 8) & 0xFF);

	/* Extract the "ascii value" */
	k = (k & 0xFF);

	/* Process "normal" keys */
	if ((s <= 58) || (s == 0xE0))
	{
		/* Enqueue it */
		if (k) Term_keypress(k);

		/* Success */
		return (0);
	}

	/* Extract the modifier flags */
	if (i & (1 << K_CTRL)) mc = TRUE;
	if (i & (1 << K_LSHIFT)) ms = TRUE;
	if (i & (1 << K_RSHIFT)) ms = TRUE;
	if (i & (1 << K_ALT)) ma = TRUE;


	/* Begin a "macro trigger" */
	Term_keypress(31);

	/* Hack -- Send the modifiers */
	if (mc) Term_keypress('C');
	if (ms) Term_keypress('S');
	if (ma) Term_keypress('A');

	/* Introduce the hexidecimal scan code */
	Term_keypress('x');

	/* Encode the hexidecimal scan code */
	Term_keypress(hexsym[s/16]);
	Term_keypress(hexsym[s%16]);

	/* End the "macro trigger" */
	Term_keypress(13);

	/* Success */
	return (0);
}


/*
 * Handle a "special request"
 *
 * The given parameters are "valid".
 */
static errr Term_xtra_ibm(int n, int v)
{
	int i;

	/* Analyze the request */
	switch (n)
	{
		/* Make a "bell" noise */
		case TERM_XTRA_NOISE:
		{
			/* Make a bell noise */
			(void)write(1, "\007", 1);

			/* Success */
			return (0);
		}

		/* Set the cursor shape */
		case TERM_XTRA_SHAPE:
		{
			/* Set cursor shape */
			curs_set(v);

			/* Success */
			return (0);
		}

		/* Flush one line of output */
		case TERM_XTRA_FROSH:
		{

#ifdef USE_VIRTUAL

# ifdef USE_WAT

			/* Copy the virtual screen to the physical screen */
			memcpy(PhysicalScreen + (v*160), VirtualScreen + (v*160), 160);

# else /* USE_WAT */

			/* Apply the virtual screen to the physical screen */
			ScreenUpdateLine(VirtualScreen + ((v*cols) << 1), v);

# endif /* USE_WAT */

#endif /* USE_VIRTUAL */

			/* Success */
			return (0);
		}

		/* Clear the screen */
		case TERM_XTRA_CLEAR:
		{

#ifdef USE_CONIO

			/* Clear the screen */
			clrscr();

#else /* USE_CONIO */

			/* Clear each line (virtual or physical) */
			for (i = 0; i < rows; i++)
			{
				/* Clear the line */
				memcpy((VirtualScreen + ((i*cols) << 1)), wiper, (cols << 1));
			}

# ifdef USE_VIRTUAL

#  ifdef USE_WAT

			/* Copy the virtual screen to the physical screen */
			memcpy(PhysicalScreen, VirtualScreen, 25*80*2);

#  else /* USE_WAT */

			/* Erase the physical screen */
			ScreenClear();

#  endif /* USE_WAT */

# endif /* USE_VIRTUAL */

#endif /* USE_CONIO */

			/* Success */
			return (0);
		}

		/* Process events */
		case TERM_XTRA_EVENT:
		{
			/* Process one event */
			return (Term_xtra_ibm_event(v));
		}

		/* Flush events */
		case TERM_XTRA_FLUSH:
		{
			/* Strip events */
			while (!Term_xtra_ibm_event(FALSE)) /* loop */;

			/* Success */
			return (0);
		}

		/* React to global changes */
		case TERM_XTRA_REACT:
		{
			/* React to "color_table" changes */
			return (Term_xtra_ibm_react());
		}

		/* Delay for some milliseconds */
		case TERM_XTRA_DELAY:
		{
			/* Delay if needed */
			if (v > 0) delay(v);

			/* Success */
			return (0);
		}
	}

	/* Unknown request */
	return (1);
}



/*
 * Move the cursor
 *
 * The given parameters are "valid".
 */
static errr Term_curs_ibm(int x, int y)
{

#ifdef USE_WAT

# ifdef USE_CONIO

	/* Place the cursor */
	gotoxy(x+1, y+1);

# else /* USE_CONIO */

	union REGS r;

	r.h.ah = 2;
	r.h.bh = 0;
	r.h.dl = x;
	r.h.dh = y;

	/* Place the cursor */
	int86(0x10, &r, &r);

# endif /* USE_CONIO */

#else /* USE_WAT */

	/* Move the cursor */
	ScreenSetCursor(y, x);

#endif /* USE_WAT */

	/* Success */
	return (0);
}


/*
 * Erase a block of the screen
 *
 * The given parameters are "valid".
 */
static errr Term_wipe_ibm(int x, int y, int n)
{

#ifdef USE_CONIO

	/* Wipe the region */
	window(x+1, y+1, x+n, y+1);
	clrscr();
	window(1, 1, cols, rows);

#else /* USE_CONIO */

	/* Wipe part of the virtual (or physical) screen */
	memcpy(VirtualScreen + ((cols*y + x)<<1), wiper, n<<1);

#endif /* USE_CONIO */

	/* Success */
	return (0);
}


/*
 * Place some text on the screen using an attribute
 *
 * The given parameters are "valid".  Be careful with "a".
 *
 * The string "cp" has length "n" and is NOT null-terminated.
 */
static errr Term_text_ibm(int x, int y, int n, byte a, const char *cp)
{
	register int i;
	register byte attr;
	register byte *dest;


	/* Handle "complex" color */
	if (use_color_complex)
	{
		/* Extract a color index */
		attr = (a & 0x0F);
	}

	/* Handle "simple" color */
	else
	{
		/* Extract a color value */
		attr = ibm_color_simple[a & 0x0F];
	}

#ifdef USE_CONIO

	/* Place the cursor */
	gotoxy(x+1, y+1);

	/* Set the attribute */
	textattr(attr);

	/* Dump the text */
	for (i = 0; i < n; i++) putch(cp[i]);

#else /* USE_CONIO */

	/* Access the virtual (or physical) screen */
	dest = VirtualScreen + (((cols * y) + x) << 1);

	/* Save the data */
	for (i = 0; i < n; i++)
	{
		/* Apply */
		*dest++ = cp[i];
		*dest++ = attr;
	}

#endif /* USE_CONIO */

	/* Success */
	return (0);
}


/*
 * Place some attr/char pairs on the screen
 *
 * The given parameters are "valid".
 */
#ifdef USE_TRANSPARENCY
static errr Term_pict_ibm(int x, int y, int n, const byte *ap, const char *cp, const byte *tap, const char *tcp)
#else /* USE_TRANSPARENCY */
static errr Term_pict_ibm(int x, int y, int n, const byte *ap, const char *cp)
#endif /* USE_TRANSPARENCY */
{
	register int i;
	register byte attr;
	register byte *dest;


#ifdef USE_CONIO

	/* Place the cursor */
	gotoxy(x+1, y+1);

	/* Dump the text */
	for (i = 0; i < n; i++)
	{
		/* Handle "complex" color */
		if (use_color_complex)
		{
			/* Extract a color index */
			attr = (ap[i] & 0x0F);
		}

		/* Handle "simple" color */
		else
		{
			/* Extract a color value */
			attr = ibm_color_simple[ap[i] & 0x0F];
		}

		/* Set the attribute */
		textattr(attr);

		/* Dump the char */
		putch(cp[i]);
	}

#else /* USE_CONIO */

	/* Access the virtual (or physical) screen */
	dest = VirtualScreen + (((cols * y) + x) << 1);

	/* Save the data */
	for (i = 0; i < n; i++)
	{
		/* Handle "complex" color */
		if (use_color_complex)
		{
			/* Extract a color index */
			attr = (ap[i] & 0x0F);
		}

		/* Handle "simple" color */
		else
		{
			/* Extract a color value */
			attr = ibm_color_simple[ap[i] & 0x0F];
		}

		/* Apply */
		*dest++ = cp[i];
		*dest++ = attr;
	}

#endif /* USE_CONIO */

	/* Success */
	return (0);
}


/*
 * Init a Term
 */
static void Term_init_ibm(term *t)
{
	/* XXX Nothing */
}


/*
 * Nuke a Term
 */
static void Term_nuke_ibm(term *t)
{

#ifdef USE_WAT

	/* Nothing */

#else /* USE_WAT */

	union REGS r;

#endif /* USE_WAT */

	/* Move the cursor to the bottom of the screen */
	Term_curs_ibm(0, rows-1);

#ifdef USE_WAT

	/* Restore the original video mode */
	_setvideomode(_DEFAULTMODE);

#else /* USE_WAT */

	/* Restore the original video mode */
	r.h.ah = 0x00;
	r.h.al = 0x03;
	int86(0x10, &r, &r);

#endif /* USE_WAT */

	/* Make the cursor visible */
	curs_set(1);
}



#ifdef USE_GRAPHICS

#ifdef USE_286

/*
 * In 286 mode we don't need to worry about translating from a 32bit
 * pointer to a 16 bit pointer so we just call the interrupt function
 *
 * Note the use of "intr()" instead of "int86()" so we can pass
 * segment registers.
 */
void enable_graphic_font(void *font)
{
	union REGPACK regs =
	{0};

	regs.h.ah = 0x11;           /* Text font function */
	regs.h.bh = 0x10;           /* Size of a character -- 16 bytes */
	regs.h.cl = 0xFF;           /* Last character in font */
	regs.x.es = FP_SEG(font);   /* Pointer to font */
	regs.x.bp = FP_OFF(font);
	intr(0x10, &regs);
};

#else /* USE_286 */

#ifdef USE_WAT

/*
 * This structure is used by the DMPI function to hold registers when
 * doing a real mode interrupt call.  (Stolen from the DJGPP <dpmi.h>
 * header file).
 */

typedef union
{
	struct
	{
		unsigned long edi;
		unsigned long esi;
		unsigned long ebp;
		unsigned long res;
		unsigned long ebx;
		unsigned long edx;
		unsigned long ecx;
		unsigned long eax;
	} d;
	struct
	{
		unsigned short di, di_hi;
		unsigned short si, si_hi;
		unsigned short bp, bp_hi;
		unsigned short res, res_hi;
		unsigned short bx, bx_hi;
		unsigned short dx, dx_hi;
		unsigned short cx, cx_hi;
		unsigned short ax, ax_hi;
		unsigned short flags;
		unsigned short es;
		unsigned short ds;
		unsigned short fs;
		unsigned short gs;
		unsigned short ip;
		unsigned short cs;
		unsigned short sp;
		unsigned short ss;
	} x;
	struct
	{
		unsigned char edi[4];
		unsigned char esi[4];
		unsigned char ebp[4];
		unsigned char res[4];
		unsigned char bl, bh, ebx_b2, ebx_b3;
		unsigned char dl, dh, edx_b2, edx_b3;
		unsigned char cl, ch, ecx_b2, ecx_b3;
		unsigned char al, ah, eax_b2, eax_b3;
	} h;
} __dpmi_regs;

unsigned  __dpmi_allocate_dos_memory(int size, unsigned *selector)
{
	union REGPACK regs =
	{0};

	regs.w.ax  = 0x100;   /* DPMI function -- allocate low memory */
	regs.w.bx  = size;    /* Number of Paragraphs to allocate */
	intr(0x31, &regs);    /* DPMI interface */

	*selector = regs.w.dx;
	return (regs.w.ax);
};

void __dpmi_free_dos_memory(unsigned sel)
{
	union REGPACK regs =
	{0};

	regs.w.ax  = 0x101;      /* DPMI function -- free low memory */
	regs.x.edx = sel;        /* PM selector for memory block */
	intr(0x31, &regs);       /* DPMI interface */
};

void __dpmi_int(int intno, __dpmi_regs *dblock)
{
	union REGPACK regs =
	{0};

	regs.w.ax  = 0x300;           /* DPMI function -- real mode interrupt */
	regs.h.bl  = intno;           /* interrupt 0x10 */
	regs.x.edi = FP_OFF(dblock);  /* Pointer to dblock (offset and segment) */
	regs.x.es  = FP_SEG(dblock);
	intr(0x31, &regs);            /* DPMI interface */
};

unsigned short __dpmi_sel = 0x0000;
#define _farsetsel(x) __dpmi_sel=(x)
extern void _farnspokeb(unsigned long offset, unsigned char value);
#pragma aux _farnspokeb =        \
          "push   fs"            \
          "mov    fs,__dpmi_sel" \
          "mov    fs:[eax],bl"   \
          "pop    fs"            \
          parm [eax] [bl];

#else /* USE_WAT */

#include <dpmi.h>
#include <go32.h>
#include <sys/farptr.h>

#endif /* USE_WAT */


/*
 * Since you cannot send 32bit pointers to a 16bit interrupt handler
 * and the video BIOS wants a (16bit) pointer to the font, we have
 * to allocate a block of dos memory, copy the font into it, then
 * translate a 32bit pointer into a 16bit pointer to that block.
 *
 * DPMI - Dos Protected Mode Interface provides functions that let
 *        us do that.
 */
void enable_graphic_font(const char *font)
{
	__dpmi_regs dblock = {{0}};

	unsigned seg, sel, i;

	/*
	 * Allocate a block of memory 4096 bytes big in `low memory' so a real
	 * mode interrupt can access it.  Real mode pointer is returned as seg:0
	 * Protected mode pointer is sel:0.
	 */
	seg = __dpmi_allocate_dos_memory(256, &sel);

	/* Copy the information into low memory buffer, by copying one byte at
	 * a time.  According to the info in <sys/farptr.h>, the functions
	 * _farsetsel() and _farnspokeb() will optimise away completely
	 */
	_farsetsel(sel);               /* Set the selector to write to */
	for (i = 0; i<4096; i++)
	{
		_farnspokeb(i, *font++);      /* Copy 1 byte into low (far) memory */
	}

	/*
	 * Now we use DPMI as a jumper to call the real mode interrupt.  This
	 * is needed because loading `es' while in protected mode with a real
	 * mode pointer will cause an Protection Fault and calling the interrupt
	 * directly using the protected mode pointer will result in garbage
	 * being received by the interrupt routine
	 */
	dblock.d.eax = 0x1100;         /* BIOS function -- set font */
	dblock.d.ebx = 0x1000;         /* bh = size of a letter; bl = 0 (reserved) */
	dblock.d.ecx = 0x00FF;         /* Last character in font */
	dblock.x.es  = seg;            /* Pointer to font segment */
	dblock.d.ebp = 0x0000;         /* Pointer to font offset */

	__dpmi_int(0x10, &dblock);

	/* We're done with the low memory, free it */
	__dpmi_free_dos_memory(sel);
};

#endif /* USE_286 */

#endif /* ALLOW_GRAPH */



/*
 * Initialize the IBM "visual module"
 *
 * Hack -- we assume that "blank space" should be "white space"
 * (and not "black space" which might make more sense).
 *
 * Note the use of "((x << 2) | (x >> 4))" to "expand" a 6 bit value
 * into an 8 bit value, without losing much precision, by using the 2
 * most significant bits as the least significant bits in the new value.
 */
errr init_ibm(void)
{
	int i;
	int mode;

	term *t = &term_screen_body;

	union REGS r;

	/* Check for "Windows" */
	if (getenv("windir"))
	{
		r.h.ah = 0x16;           /* Windows API Call -- Set device focus */
		r.h.al = 0x8B;           /* Causes Dos boxes to become fullscreen */
		r.h.bh = r.h.bl = 0x00;  /* 0x0000 = current Dos box */
		int86(0x2F, &r, &r);       /* Call the Windows API */
	};

	/* Initialize "color_table" */
	for (i = 0; i < 16; i++)
	{
		long rv, gv, bv;

		/* Extract desired values */
		rv = angband_color_table[i][1] >> 2;
		gv = angband_color_table[i][2] >> 2;
		bv = angband_color_table[i][3] >> 2;

		/* Extract the "complex" codes */
		ibm_color_complex[i] = ((rv) | (gv << 8) | (bv << 16));

		/* Save the "simple" codes */
		angband_color_table[i][0] = ibm_color_simple[i];
	}

#ifdef USE_WAT

	/* Set the video mode */
	if (_setvideomode(_VRES16COLOR))
	{
		mode = 0x13;
	}

	/* Wimpy monitor */
	else
	{
		mode = 0x03;
	}

	/* Force 25 line mode */
	_setvideomode(_TEXTC80);
	_settextrows(25);

#else /* USE_WAT */

	/* Set video mode */
	r.h.ah = 0x00;
	r.h.al = 0x13; /* VGA only mode */
	int86(0x10, &r, &r);

	/* Get video mode */
	r.h.ah = 0x0F;
	int86(0x10, &r, &r);
	mode = r.h.al;

	/* Set video mode */
	r.h.ah = 0x00;
	r.h.al = 0x03; /* Color text mode */
	int86(0x10, &r, &r);

#endif /* USE_WAT */

	/* Check video mode */
	if (mode == 0x13)
	{
		/* Remember the mode */
		use_color_complex = TRUE;

		/* Instantiate the color set */
		activate_color_complex();
	}

#ifdef USE_GRAPHICS

	/* Try to activate bitmap graphics */
	if (arg_graphics && use_color_complex)
	{
		FILE *f;

		char buf[4096];

		/* Build the filename */
		path_build(buf, 1024, ANGBAND_DIR_XTRA, "angband.fnt");

		/* Open the file */
		f = fopen(buf, "rb");

		/* Okay */
		if (f)
		{
			/* Load the bitmap data */
			if (fread(buf, 1, 4096, f) != 4096)
			{
				quit("Corrupt 'angband.fnt' file");
			}

			/* Close the file */
			fclose(f);

			/* Enable graphics */
			enable_graphic_font(buf);

			/* Enable colors (again) */
			activate_color_complex();

			/* Use graphics */
			use_graphics = TRUE;
		}
	}

#endif

#ifdef USE_CONIO
#else /* USE_CONIO */

	/* Build a "wiper line" */
	for (i = 0; i < 80; i++)
	{
		/* Space */
		wiper[2*i] = ' ';

		/* Black */
		wiper[2*i+1] = TERM_WHITE;
	}

#endif /* USE_CONIO */


#ifdef USE_VIRTUAL

	/* Make the virtual screen */
	C_MAKE(VirtualScreen, rows * cols * 2, byte);

#endif /* USE_VIRTUAL */


	/* Erase the screen */
	Term_xtra_ibm(TERM_XTRA_CLEAR, 0);


	/* Place the cursor */
	Term_curs_ibm(0, 0);


	/* Access the "default" cursor info */
	r.h.ah = 3;
	r.h.bh = 0;

	/* Make the call */
	int86(0x10, &r, &r);

	/* Extract the standard cursor info */
	saved_cur_v = 1;
	saved_cur_high = r.h.ch;
	saved_cur_low = r.h.cl;


	/* Initialize the term */
	term_init(t, 80, 24, 256);

#ifdef USE_CONIO
#else /* USE_CONIO */

	/* Always use "Term_pict()" */
	t->always_pict = TRUE;

#endif /* USE_CONIO */

	/* Use "white space" to erase */
	t->attr_blank = TERM_WHITE;
	t->char_blank = ' ';

	/* Prepare the init/nuke hooks */
	t->init_hook = Term_init_ibm;
	t->nuke_hook = Term_nuke_ibm;

	/* Connect the hooks */
	t->xtra_hook = Term_xtra_ibm;
	t->curs_hook = Term_curs_ibm;
	t->wipe_hook = Term_wipe_ibm;
	t->text_hook = Term_text_ibm;
	t->pict_hook = Term_pict_ibm;

	/* Save it */
	term_screen = t;

	/* Activate it */
	Term_activate(term_screen);

	/* Success */
	return 0;
}


#endif /* USE_IBM */

