// WL_SCALE.C

#include "WL_DEF.H"
#pragma hdrstop

#define OP_RETF	0xcb

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

						  GLOBALS

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

t_compscale far *scaledirectory[MAXSCALEHEIGHT+1];
long			fullscalefarcall[MAXSCALEHEIGHT+1];

int			maxscale,maxscaleshl2;

byte far	*scalermemory;
byte _seg	*endscalermemory;
long		freescalermemory;


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

						  LOCALS

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

unsigned BuildCompScale (int height, byte far *code);

int			stepbytwo;

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

/*
==============
=
= BadScale
=
==============
*/

void far BadScale (void)
{
	Quit ("BadScale called!");
}


/*
==========================
=
= SetupScaling
=
==========================
*/

long SetupScaling (int maxscaleheight)
{
	int		i,x,y;
	byte	far *dest;
	unsigned	seg,ofs;
	long	size;


	maxscaleheight/=2;			// one scaler every two pixels

	maxscale = maxscaleheight-1;
	maxscaleshl2 = maxscale<<2;

	dest = scalermemory;

//
// build the compiled scalers
//
	stepbytwo = viewheight/2;	// save space by double stepping

	for (i=1;i<=maxscaleheight;i++)
	{
		seg = FP_SEG(dest);
		ofs = (FP_OFF(dest)+15)&~15;
		dest = MK_FP(seg+ofs/16,0);

		scaledirectory[i] = (t_compscale far *)dest;
		size = BuildCompScale (i*2,dest);
		dest += size;

		if ((byte huge *)dest-(byte huge *)scalermemory > MAXSCALERMEMORY)
			Quit ("Compiled scalars exceeded allocated space!");

		if (i>=stepbytwo)
			i+= 2;
	}

//
// get far call addresses
//
	for (i=1;i<=maxscaleheight;i++)
	{
		fullscalefarcall[i] = (long)scaledirectory[i] + scaledirectory[i]->codeofs[0];
		if (i>=stepbytwo)
		{
			scaledirectory[i+1] = scaledirectory[i];
			fullscalefarcall[i+1] = (long)scaledirectory[i] + scaledirectory[i]->codeofs[0];
			scaledirectory[i+2] = scaledirectory[i];
			fullscalefarcall[i+2] = (long)scaledirectory[i] + scaledirectory[i]->codeofs[0];
			i+=2;
		}
	}
	scaledirectory[0] = scaledirectory[1];
	fullscalefarcall[0] = fullscalefarcall[1];

//
// check for oversize wall drawing
//
	for (i=maxscaleheight;i<MAXSCALEHEIGHT;i++)
		fullscalefarcall[i] = (long)BadScale;

	seg = FP_SEG(dest);
	ofs = (FP_OFF(dest)+15)&~15;
	endscalermemory = (void _seg *)(seg+ofs/16);
	size = (byte huge *)dest-(byte huge *)scalermemory;
	freescalermemory = MAXSCALERMEMORY-16-size;

	return size;
}

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

/*
========================
=
= BuildCompScale
=
= Builds a compiled scaler object that will scale a 64 tall object to
= the given height (centered vertically on the screen)
=
= height should be even
=
= Call with
= ---------
= DS:SI		Source for scale
= ES:DI		Dest for scale
=
= Calling the compiled scaler only destroys AL
=
========================
*/

unsigned BuildCompScale (int height, byte far *code)
{
	t_compscale 	far *work;

	int			i;
	long		fix,step;
	unsigned	src,totalscaled,totalsize;
	int			startpix,endpix,toppix;

	work = (t_compscale far *)code;

	step = ((long)height<<16) / 64;
	code = &work->code[0];
	toppix = (viewheight-height)/2;
	fix = 0;

	for (src=0;src<=64;src++)
	{
		startpix = fix>>16;
		fix += step;
		endpix = fix>>16;

		if (endpix>startpix)
			work->width[src] = endpix-startpix;
		else
			work->width[src] = 0;

//
// mark the start of the code
//
		work->codeofs[src] = FP_OFF(code);

//
// compile some code if the source pixel generates any screen pixels
//
		startpix+=toppix;
		endpix+=toppix;

		if (startpix == endpix || endpix < 0 || startpix >= viewheight || src == 64)
			continue;

	//
	// mov al,[si+src]
	//
		*code++ = 0x8a;
		*code++ = 0x44;
		*code++ = src;

		for (;startpix<endpix;startpix++)
		{
			if (startpix >= viewheight)
				break;						// off the bottom of the view area
			if (startpix < 0)
				continue;					// not into the view area

		//
		// mov [es:di+heightofs],al
		//
			*code++ = 0x26;
			*code++ = 0x88;
			*code++ = 0x85;
			*((unsigned far *)code)++ = startpix*SCREENBWIDE;
		}

	}

//
// retf
//
	*code++ = 0xcb;

	totalsize = FP_OFF(code);

	return totalsize;
}


/*
=======================
=
= ScaleLine
=
= linescale should have the high word set to the segment of the scaler
=
=======================
*/

extern	int			slinex,slinewidth;
extern	unsigned	far *linecmds;
extern	long		linescale;
extern	unsigned	maskword;

byte	mask1,mask2,mask3;


void near ScaleLine (void)
{
asm	mov	cx,WORD PTR [linescale+2]
asm	mov	es,cx						// segment of scaler

asm	mov bp,WORD PTR [linecmds]
asm	mov	dx,SC_INDEX+1				// to set SC_MAPMASK

asm	mov	bx,[slinex]
asm	mov	di,bx
asm	shr	di,2						// X in bytes
asm	add	di,[bufferofs]
asm	and	bx,3
asm	shl	bx,3
asm	add	bx,[slinewidth]				// bx = (pixel*8+pixwidth)
asm	mov	al,BYTE [mapmasks3-1+bx]	// -1 because pixwidth of 1 is first
asm	mov	ds,WORD PTR [linecmds+2]
asm	or	al,al
asm	jz	notthreebyte				// scale across three bytes
asm	jmp	threebyte
notthreebyte:
asm	mov	al,BYTE PTR ss:[mapmasks2-1+bx]	// -1 because pixwidth of 1 is first
asm	or	al,al
asm	jnz	twobyte						// scale across two bytes

//
// one byte scaling
//
asm	mov	al,BYTE PTR ss:[mapmasks1-1+bx]	// -1 because pixwidth of 1 is first
asm	out	dx,al						// set map mask register

scalesingle:

asm	mov	bx,[ds:bp]					// table location of rtl to patch
asm	or	bx,bx
asm	jz	linedone					// 0 signals end of segment list
asm	mov	bx,[es:bx]
asm	mov	dl,[es:bx]					// save old value
asm	mov	BYTE PTR es:[bx],OP_RETF	// patch a RETF in
asm	mov	si,[ds:bp+4]				// table location of entry spot
asm	mov	ax,[es:si]
asm	mov	WORD PTR ss:[linescale],ax	// call here to start scaling
asm	mov	si,[ds:bp+2]				// corrected top of shape for this segment
asm	add	bp,6						// next segment list

asm	mov	ax,SCREENSEG
asm	mov	es,ax
asm	call ss:[linescale]				// scale the segment of pixels

asm	mov	es,cx						// segment of scaler
asm	mov	BYTE PTR es:[bx],dl			// unpatch the RETF
asm	jmp	scalesingle					// do the next segment


//
// done
//
linedone:
asm	mov	ax,ss
asm	mov	ds,ax
return;

//
// two byte scaling
//
twobyte:
asm	mov	ss:[mask2],al
asm	mov	al,BYTE PTR ss:[mapmasks1-1+bx]	// -1 because pixwidth of 1 is first
asm	mov	ss:[mask1],al

scaledouble:

asm	mov	bx,[ds:bp]					// table location of rtl to patch
asm	or	bx,bx
asm	jz	linedone					// 0 signals end of segment list
asm	mov	bx,[es:bx]
asm	mov	cl,[es:bx]					// save old value
asm	mov	BYTE PTR es:[bx],OP_RETF	// patch a RETF in
asm	mov	si,[ds:bp+4]				// table location of entry spot
asm	mov	ax,[es:si]
asm	mov	WORD PTR ss:[linescale],ax	// call here to start scaling
asm	mov	si,[ds:bp+2]				// corrected top of shape for this segment
asm	add	bp,6						// next segment list

asm	mov	ax,SCREENSEG
asm	mov	es,ax
asm	mov	al,ss:[mask1]
asm	out	dx,al						// set map mask register
asm	call ss:[linescale]				// scale the segment of pixels
asm	inc	di
asm	mov	al,ss:[mask2]
asm	out	dx,al						// set map mask register
asm	call ss:[linescale]				// scale the segment of pixels
asm	dec	di

asm	mov	es,WORD PTR ss:[linescale+2] // segment of scaler
asm	mov	BYTE PTR es:[bx],cl			// unpatch the RETF
asm	jmp	scaledouble					// do the next segment


//
// three byte scaling
//
threebyte:
asm	mov	ss:[mask3],al
asm	mov	al,BYTE PTR ss:[mapmasks2-1+bx]	// -1 because pixwidth of 1 is first
asm	mov	ss:[mask2],al
asm	mov	al,BYTE PTR ss:[mapmasks1-1+bx]	// -1 because pixwidth of 1 is first
asm	mov	ss:[mask1],al

scaletriple:

asm	mov	bx,[ds:bp]					// table location of rtl to patch
asm	or	bx,bx
asm	jz	linedone					// 0 signals end of segment list
asm	mov	bx,[es:bx]
asm	mov	cl,[es:bx]					// save old value
asm	mov	BYTE PTR es:[bx],OP_RETF	// patch a RETF in
asm	mov	si,[ds:bp+4]				// table location of entry spot