//kernel.c
//08/13/03 Josh Holtrop
//Holtrop's Operating System

#include "k_defines.h"
#include "functions.h"

void isr(int num);
void k_init();

#include "functions.c"

//9000:306

typedef struct{
	USHORT	ModeAttributes;
	UCHAR	WinAAttributes;
	UCHAR	WinBAttributes;
	USHORT	WinGranularity;
	USHORT	WinSize;
	USHORT	WinASegment;
	USHORT	WinBSegment;
	UINT	WinFuncPtr;
	USHORT	BytesPerScanLine;

	USHORT	XResolution;
	USHORT	YResolution;
	UCHAR	XCharSize;
	UCHAR	YCharSize;
	UCHAR	NumberOfPlanes;
	UCHAR	BitsPerPixel;
	UCHAR	NumberOfBanks;
	UCHAR	MemoryModel;
	UCHAR	BankSize;
	UCHAR	NumberOfImagePages;
	UCHAR	Reserved1;

	UCHAR	RedMaskSize;
	UCHAR	RedFieldPosition;
	UCHAR	GreenMaskSize;
	UCHAR	GreenFieldPosition;
	UCHAR	BlueMaskSize;
	UCHAR	BlueFieldPosition;
	UCHAR	RsvdMaskSize;
	UCHAR	RsvdFieldPosition;
	UCHAR	DirectColorModeInfo;

	dword	PhysBasePtr;
	UINT	OffScreenMemOffset;
	USHORT	OffScreenMemSize;
	UCHAR	Reserved[206];
} ModeInfoBlock;




void k_init()
{
	remap_pics(0x20, 0x28);
	//set timer : 2e9c = 100hz
	outportb(0x43, 0x34);
	outportb(0x40, 0x9c); //lsb
	outportb(0x40, 0x2e); //msb
	enable_ints();
	ModeInfoBlock *mib = (ModeInfoBlock *) 0x90306;
	UINT *vid = (UINT *) (mib->PhysBasePtr);
	UINT a;
	UINT tot = ((mib->XResolution) * (mib->YResolution));
	word step = 0x1000000 / tot;			//step to increase color by for each pixel
	dword color = 0;
	for (a = 0; a < tot; a++)
	{
		vid[a] = color;
		color += step;
	}
}

void isr(int num)
{
	if (num == 0x20)
	{
		(*(char*)0xB8000)++;
		*(char*)0xB8001 = 7;
		eoi();
	}
}