[LinuxBIOS] Building an irq table - Help

Ok I am a little confused on how to tell what devices are what in irc_tablec.c
How do I tell?? Also where does the value for the "bitmap" come from?

Thanks for your help - Joe

/* bus,     dev|fn,
{0x01,(0x08<<3)|0x0,
{0x00,(0x1f<<3)|0x0,
{0x00,(0x1d<<3)|0x0,
{0x00,(0x00<<3)|0x0,
{0x00,(0x01<<3)|0x0,
{0x01,(0x00<<3)|0x0,
{0x01,(0x01<<3)|0x0,
{0x01,(0x02<<3)|0x0,
{0x01,(0x09<<3)|0x0,
{0x01,(0x06<<3)|0x0,
{0x01,(0x07<<3)|0x0,
{0x00,(0x02<<3)|0x0,