#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"

#include <libg.h>
#include "screen.h"
#include "vga.h"

extern Cursor curcursor;

/*
 * IBM RGB524.
 * 170/220MHz High Performance Palette DAC.
 *
 * Assumes hooked up to an S3 Vision96[48].
 */
enum {
	IndexLo		= 0x00,
	IndexHi		= 0x01,
	Data		= 0x02,
	IndexCtl	= 0x03,
};

enum {						/* index registers */
	CursorCtl	= 0x30,
	CursorXLo	= 0x31,
	CursorXHi	= 0x32,
	CursorYLo	= 0x33,
	CursorYHi	= 0x34,
	CursorHotX	= 0x35,
	CursorHotY	= 0x36,

	CursorR1	= 0x40,
	CursorG1	= 0x41,
	CursorB1	= 0x42,
	CursorR2	= 0x43,
	CursorG2	= 0x44,
	CursorB2	= 0x45,
	CursorR3	= 0x46,
	CursorG3	= 0x47,
	CursorB3	= 0x48,

	CursorArray	= 0x100,
};

/*
 * Lower 2-bits of indirect DAC register
 * addressing.
 */
static ushort dacxreg[4] = {
	PaddrW, Pdata, Pixmask, PaddrR
};

static uchar
setrs2(void)
{
	uchar rs2;

	rs2 = vgaxi(Crtx, 0x55);
	vgaxo(Crtx, 0x55, (rs2 & 0xFC)|0x01);

	return rs2;
}

static void
rgb524xo(int index, uchar data)
{
	vgao(dacxreg[IndexLo], index & 0xFF);
	vgao(dacxreg[IndexHi], (index>>8) & 0xFF);

	vgao(dacxreg[Data], data);
}

static void
restorers2(uchar rs2)
{
	vgaxo(Crtx, 0x55, rs2);
}

static void
load(Cursor *c)
{
	uchar p, p0, p1, rs2;
	int x, y;

	/*
	 * Lock the DAC registers so we can update the
	 * cursor bitmap if necessary.
	 * If it's the same as the last cursor we loaded,
	 * just make sure it's enabled.
	 */
	lock(&palettelock);
	rs2 = setrs2();
	if(memcmp(c, &curcursor, sizeof(Cursor)) == 0){
		rgb524xo(CursorCtl, 0x23);
		restorers2(rs2);
		unlock(&palettelock);
		return;
	}
	memmove(&curcursor, c, sizeof(Cursor));

	/*
	 * Make sure cursor is off by initialising the cursor
	 * control to defaults.
	 */
	rgb524xo(CursorCtl, 0x00);

	/*
	 * Set auto-increment mode for index-register addressing
	 * and initialise the cursor array index.
	 */
	vgao(dacxreg[IndexCtl], 0x01);
	vgao(dacxreg[IndexLo], CursorArray & 0xFF);
	vgao(dacxreg[IndexHi], (CursorArray>>8) & 0xFF);

	/*
	 * Initialise the 32x32 cursor RAM array. There are 2 planes,
	 * p0 and p1. Data is written 4 pixels per byte, with p1 the
	 * MS bit of each pixel.
	 * The cursor is set in X-Windows mode which gives the following
	 * truth table:
	 *	p1 p0	colour
	 *	 0  0	underlying pixel colour
	 *	 0  1	underlying pixel colour
	 *	 1  0	cursor colour 1
	 *	 1  1	cursor colour 2
	 * Put the cursor into the top-left of the 32x32 array.
	 */
	for(y = 0; y < 32; y++){
		for(x = 0; x < 32/8; x++){
			if(x < 16/8 && y < 16){
				p0 = c->clr[x+y*2];
				p1 = c->set[x+y*2];

				p = 0x00;
				if(p1 & 0x80)
					p |= 0xC0;
				else if(p0 & 0x80)
					p |= 0x80;
				if(p1 & 0x40)
					p |= 0x30;
				else if(p0 & 0x40)
					p |= 0x20;
				if(p1 & 0x20)
					p |= 0x0C;
				else if(p0 & 0x20)
					p |= 0x08;
				if(p1 & 0x10)
					p |= 0x03;
				else if(p0 & 0x10)
					p |= 0x02;
				vgao(dacxreg[Data], p);

				p = 0x00;
				if(p1 & 0x08)
					p |= 0xC0;
				else if(p0 & 0x08)
					p |= 0x80;
				if(p1 & 0x04)
					p |= 0x30;
				else if(p0 & 0x04)
					p |= 0x20;
				if(p1 & 0x02)
					p |= 0x0C;
				else if(p0 & 0x02)
					p |= 0x08;
				if(p1 & 0x01)
					p |= 0x03;
				else if(p0 & 0x01)
					p |= 0x02;
				vgao(dacxreg[Data], p);
			}
			else{
				vgao(dacxreg[Data], 0x00);
				vgao(dacxreg[Data], 0x00);
			}
		}
	}

	/*
	 * Initialise the cursor hot-point,
	 * enable the cursor and restore state.
	 */
	rgb524xo(CursorHotX, -c->offset.x);
	rgb524xo(CursorHotY, -c->offset.y);

	rgb524xo(CursorCtl, 0x23);

	restorers2(rs2);
	unlock(&palettelock);
}

static void
enable(void)
{
	uchar rs2;

	lock(&palettelock);
	rs2 = setrs2();

	/*
	 * Make sure cursor is off by initialising the cursor
	 * control to defaults.
	 */
	rgb524xo(CursorCtl, 0x00);

	/*
	 * Cursor colour 1 (white),
	 * cursor colour 2 (black).
	 */
	rgb524xo(CursorR1, Pwhite); rgb524xo(CursorG1, Pwhite); rgb524xo(CursorB1, Pwhite);
	rgb524xo(CursorR2, Pblack); rgb524xo(CursorG2, Pblack); rgb524xo(CursorB2, Pblack);

	/*
	 * Enable the cursor, 32x32, mode 2.
	 */
	rgb524xo(CursorCtl, 0x23);

	restorers2(rs2);
	unlock(&palettelock);
}

static int
move(Point p)
{
	uchar rs2;

	if(canlock(&palettelock) == 0)
		return 1;
	rs2 = setrs2();

	rgb524xo(CursorXLo, p.x & 0xFF);
	rgb524xo(CursorXHi, (p.x>>8) & 0x0F);
	rgb524xo(CursorYLo, p.y & 0xFF);
	rgb524xo(CursorYHi, (p.y>>8) & 0x0F);

	restorers2(rs2);
	unlock(&palettelock);

	return 0;
}

static void
disable(void)
{
	uchar rs2;

	lock(&palettelock);
	rs2 = setrs2();

	rgb524xo(CursorCtl, 0x00);

	restorers2(rs2);
	unlock(&palettelock);
}

Hwgc rgb524hwgc = {
	"rgb524hwgc",
	enable,
	load,
	move,
	disable,

	0,
};

void
vgargb524link(void)
{
	addhwgclink(&rgb524hwgc);
}