#include <stdlib.h>
#include <conio.h>

typedef unsigned int Boolean;
enum { False, True };

unsigned int ports[4] = { 0x220, 0x240, 0x280, 0x2c0 };

Boolean PortSearch(void);
void WriteRegister(unsigned int, unsigned char, unsigned char);
unsigned char ReadRegister(unsigned int, unsigned char);


main()
{
	PortSearch();
}


Boolean PortSearch(void)
{
	int i, j;

	for(i = 3; i >= 0; i--)
	{
		printf("Checking port %x\n", ports[i]);

		// use the 16 bit tone period registers to write a specific pattern of data
		for(j = 0; j <= 5; j++)
		{
			WriteRegister(ports[i], j, j);
		}

		for(j = 0; j <= 5; j++)
		{
			if(ReadRegister(ports[i], j) != j)
			{
				break;
			}
		}

		if(j == 6)
		{
			printf("Port found %x\n", ports[i]);
			break; 
		}
		else
		{
			printf("Port %x  detection failed\n", ports[i]);
		}
	}
}


void WriteRegister(port, reg, data)
unsigned int port;
unsigned char reg;
unsigned char data;
{
	int i;

	// select register
	outp(port, reg);

	// write and verify register
	for(i = 0; i < 10; i++)
	{
		outp(port + 1, data);

		if(inp(port + 1) == data)
		{
			break;
		}
	}
}

unsigned char ReadRegister(port, reg)
unsigned int port;
unsigned char reg;
{
	outp(port, reg);
	return(inp(port + 1));
}