io.h

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

enum {
	BusCBUS		= 0,		/* Corollary CBUS */
	BusCBUSII,			/* Corollary CBUS II */
	BusEISA,				/* Extended ISA */
	BusFUTURE,			/* IEEE Futurebus */
	BusINTERN,			/* Internal bus */
	BusISA,				/* Industry Standard Architecture */
	BusMBI,				/* Multibus I */
	BusMBII,				/* Multibus II */
	BusMCA,				/* Micro Channel Architecture */
	BusMPI,				/* MPI */
	BusMPSA,				/* MPSA */
	BusNUBUS,			/* Apple Macintosh NuBus */
	BusPCI,				/* Peripheral Component Interconnect */
	BusPCMCIA,			/* PC Memory Card International Association */
	BusTC,				/* DEC TurboChannel */
	BusVL,				/* VESA Local bus */
	BusVME,				/* VMEbus */
	BusXPRESS,			/* Express System Bus */
	BusPPC				/* Power PC internal bus */
};

#define MKBUS(t,b,d,f)	(((t)<<24)|(((b)&0xFF)<<16)|(((d)&0x1F)<<11)|(((f)&0x07)<<8))
#define BUSFNO(tbdf)	(((tbdf)>>8)&0x07)
#define BUSDNO(tbdf)	(((tbdf)>>11)&0x1F)
#define BUSBNO(tbdf)	(((tbdf)>>16)&0xFF)
#define BUSTYPE(tbdf)	((tbdf)>>24)
#define BUSBDF(tbdf)	((tbdf)&0x00FFFF00)
#define BUSUNKNOWN	(-1)