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

enum {
	Black,
	Blue,
	Green,
	Cyan,
	Red,
	Magenta,
	Brown,
	Grey,

	Bright = 0x08,
	Blinking = 0x80,

	Yellow = Bright|Brown,
	White = Bright|Grey,
};
	
enum {
	Width		= 80*2,
	Height		= 25,

	Attr		= (Black<<4)|Grey,	/* high nibble background
						 * low foreground
						 */
};

#define CGASCREENBASE	((uchar*)KADDR(0xB8000))

static int cgapos;
static Lock cgascreenlock;

static Rune ibm437[256] = {
0x2007, 0x263a, 0x263b, 0x2665, 0x2666, 0x2663, 0x2660, 0x2022,
0x25d8, 0x25cb, 0x25d9, 0x2642, 0x2640, 0x266a, 0x266b, 0x263c,
0x25ba, 0x25c4, 0x2195, 0x203c, 0x00b6, 0x00a7, 0x25ac, 0x21a8,
0x2191, 0x2193, 0x2192, 0x2190, 0x221f, 0x2193, 0x25b2, 0x25bc,
0x0020, 0x0021, 0x0022, 0x0023, 0x0024, 0x0025, 0x0026, 0x0027,
0x0028, 0x0029, 0x002A, 0x002B, 0x002C, 0x002D, 0x002E, 0x002F,
0x0030, 0x0031, 0x0032, 0x0033, 0x0034, 0x0035, 0x0036, 0x0037,
0x0038, 0x0039, 0x003A, 0x003B, 0x003C, 0x003D, 0x003E, 0x003F,
0x0040, 0x0041, 0x0042, 0x0043, 0x0044, 0x0045, 0x0046, 0x0047,
0x0048, 0x0049, 0x004A, 0x004B, 0x004C, 0x004D, 0x004E, 0x004F,
0x0050, 0x0051, 0x0052, 0x0053, 0x0054, 0x0055, 0x0056, 0x0057,
0x0058, 0x0059, 0x005A, 0x005B, 0x005C, 0x005D, 0x005E, 0x005F,
0x0060, 0x0061, 0x0062, 0x0063, 0x0064, 0x0065, 0x0066, 0x0067,
0x0068, 0x0069, 0x006A, 0x006B, 0x006C, 0x006D, 0x006E, 0x006F,
0x0070, 0x0071, 0x0072, 0x0073, 0x0074, 0x0075, 0x0076, 0x0077,
0x0078, 0x0079, 0x007A, 0x007B, 0x007C, 0x007D, 0x007E, 0x007F,
0x00C7, 0x00FC, 0x00E9, 0x00E2, 0x00E4, 0x00E0, 0x00E5, 0x00E7,
0x00EA, 0x00EB, 0x00E8, 0x00EF, 0x00EE, 0x00EC, 0x00C4, 0x00C5,
0x00C9, 0x00E6, 0x00C6, 0x00F4, 0x00F6, 0x00F2, 0x00FB, 0x00F9,
0x00FF, 0x00D6, 0x00DC, 0x00A2, 0x00A3, 0x00A5, 0x20A7, 0x0192,
0x00E1, 0x00ED, 0x00F3, 0x00FA, 0x00F1, 0x00D1, 0x00AA, 0x00BA,
0x00BF, 0x2310, 0x00AC, 0x00BD, 0x00BC, 0x00A1, 0x00AB, 0x00BB,
0x2591, 0x2592, 0x2593, 0x2502, 0x2524, 0x2561, 0x2562, 0x2556,
0x2555, 0x2563, 0x2551, 0x2557, 0x255D, 0x255C, 0x255B, 0x2510,
0x2514, 0x2534, 0x252C, 0x251C, 0x2500, 0x253C, 0x255E, 0x255F,
0x255A, 0x2554, 0x2569, 0x2566, 0x2560, 0x2550, 0x256C, 0x2567,
0x2568, 0x2564, 0x2565, 0x2559, 0x2558, 0x2552, 0x2553, 0x256B,
0x256A, 0x2518, 0x250C, 0x2588, 0x2584, 0x258C, 0x2590, 0x2580,
0x03B1, 0x00DF, 0x0393, 0x03C0, 0x03A3, 0x03C3, 0x00B5, 0x03C4,
0x03A6, 0x0398, 0x03A9, 0x03B4, 0x221E, 0x03C6, 0x03B5, 0x2229,
0x2261, 0x00B1, 0x2265, 0x2264, 0x2320, 0x2321, 0x00F7, 0x2248,
0x00B0, 0x2219, 0x00B7, 0x221A, 0x207F, 0x00B2, 0x25A0, 0x00A0,
};

static uchar
cgaregr(int index)
{
	outb(0x3D4, index);
	return inb(0x3D4+1) & 0xFF;
}

static void
cgaregw(int index, int data)
{
	outb(0x3D4, index);
	outb(0x3D4+1, data);
}

static void
movecursor(void)
{
	cgaregw(0x0E, (cgapos/2>>8) & 0xFF);
	cgaregw(0x0F, cgapos/2 & 0xFF);
	CGASCREENBASE[cgapos+1] = Attr;
}

static void
cgascreenputr(Rune c)
{
	int i;
	uchar *p;

	if(c == '\n'){
		cgapos = cgapos/Width;
		cgapos = (cgapos+1)*Width;
	}
	else if(c == '\t'){
		i = 8 - ((cgapos/2)&7);
		while(i-->0)
			cgascreenputr(' ');
	}
	else if(c == '\b'){
		if(cgapos >= 2)
			cgapos -= 2;
		cgascreenputr(' ');
		cgapos -= 2;
	}
	else{
		if(c < ' ' || c >= 127)
			for(i = 0;; i++){
				if(i == nelem(ibm437)){
					c = 254;
					break;
				}
				if(ibm437[i] == c){
					c = i;
					break;
				}
			}
		CGASCREENBASE[cgapos++] = c;
		CGASCREENBASE[cgapos++] = Attr;
	}
	if(cgapos >= Width*Height){
		memmove(CGASCREENBASE, &CGASCREENBASE[Width], Width*(Height-1));
		p = &CGASCREENBASE[Width*(Height-1)];
		for(i=0; i<Width/2; i++){
			*p++ = ' ';
			*p++ = Attr;
		}
		cgapos = Width*(Height-1);
	}
	movecursor();
}

static void
cgascreenputs(char* s, int n)
{
	int i;
	Rune r;

	if(!islo()){
		/*
		 * Don't deadlock trying to
		 * print in an interrupt.
		 */
		if(!canlock(&cgascreenlock))
			return;
	}
	else
		lock(&cgascreenlock);

	while(n > 0 && fullrune(s, n)){
		i = chartorune(&r, s);
		n -= i;
		s += i;
		cgascreenputr(r);
	}

	unlock(&cgascreenlock);
}

void
screeninit(void)
{

	cgapos = cgaregr(0x0E)<<8;
	cgapos |= cgaregr(0x0F);
	cgapos *= 2;

	screenputs = cgascreenputs;
}