#include "../include/pci.h"
#include "../include/system.h"
#include "../include/port.h"
#include "../include/scrn.h"

uint32_t Read(uint16_t busNumber, uint16_t deviceNumber, uint16_t functionNumber, uint32_t registerOffset)
{
	puts("Read ");
	puts(int_to_string(functionNumber, 10));
	puts("\n");
    uint32_t id =
    0x1 << 31
    | ((busNumber & 0xFF) << 16)
    | ((deviceNumber & 0x1F) << 11)
    | ((functionNumber & 0x07) << 8)
	| (registerOffset & 0xFC);
	Write32Bit(0xCF8, id);
	uint32_t result = Read32Bit(0xCFC);	
	return result >> (8 * (registerOffset %4));
}

void Write(uint16_t busNumber, uint16_t deviceNumber, uint16_t functionNumber, uint32_t registerOffset, uint32_t value)
{
    uint32_t id =
    0x1 << 31
    | ((busNumber & 0xFF) << 16)
    | ((deviceNumber & 0x1F) << 11)
    | ((functionNumber & 0x07) << 8)
	| (registerOffset & 0xFC);
	Write32Bit(0xCF8, id);
	Write32Bit(0xCFC, value);
}

bool DeviceHasFunctions(uint16_t bus, uint16_t device)
{
	//Checks the 7th bit to determine if the device has a function.
	return Read(bus, device, 0, 0x0E) & (1 << 7);
}

void EnumPCISubsystem()
{
	for(int bus = 0; bus < 8; bus++)
	{
		for(int device = 0; device < 32; device++)
		{
			int functionCount = DeviceHasFunctions(bus, device) ? 8 : 1;//8 or 1

			for(int function = 0; function < functionCount; function++)
			{
				//puts(", Function ");
				//puts(int_to_string(function, 16));
				struct DeviceDescriptor dev = {0};
				dev = GetDeviceDescriptor(bus, device, function);

				if(dev.VendorId == 0x0000 || dev.VendorId == 0xFFFF)
					break;//Break loop, no more funcitons.
				//puts("PCI BUS ");
				//puts(int_to_string(bus, 16));
				//puts("Device ");
				//puts(int_to_string(device, 16));
				//puts(" = Vendor ");
				//puts(int_to_string(dev.VendorId, 16));
				//puts(", Device ");
				//puts(int_to_string(dev.DeviceId, 16));
				//puts(" Class ");
				//puts(int_to_string(dev.ClassId, 16));
				//puts("\n");
			}
		}
	}
}

struct DeviceDescriptor GetDeviceDescriptor(uint16_t busNumber, uint16_t deviceNumber, uint16_t functionNumber)
{
	struct DeviceDescriptor result;
	
	result.Bus = busNumber;
    result.Device = deviceNumber;
	result.Function = functionNumber;

	result.VendorId = Read(busNumber, deviceNumber, functionNumber, 0x00);
	result.DeviceId = Read(busNumber, deviceNumber, functionNumber, 0x02);

	result.ClassId = Read(busNumber, deviceNumber, functionNumber, 0x0B);
	result.SubClassId = Read(busNumber, deviceNumber, functionNumber, 0x0A);
	result.InterfaceId = Read(busNumber, deviceNumber, functionNumber, 0x09);

	result.Revision = Read(busNumber, deviceNumber, functionNumber, 0x08);
	result.Interrupt = Read(busNumber, deviceNumber, functionNumber, 0x3C);

	return result;
}