/* * snull.h -- definitions for the network module * * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet * Copyright (C) 2001 O'Reilly & Associates * * The source code in this file can be freely used, adapted, * and redistributed in source or binary form, so long as an * acknowledgment appears in derived source files.  The citation * should list that the code comes from the book "Linux Device * Drivers" by Alessandro Rubini and Jonathan Corbet, published * by O'Reilly & Associates.   No warranty is attached; * we cannot take responsibility for errors or fitness for use. *//* * Macros to help debugging */#undef PDEBUG             /* undef it, just in case */#ifdef SNULL_DEBUG#  ifdef __KERNEL__     /* This one if debugging is on, and kernel space */#    define PDEBUG(fmt, args...) printk( KERN_DEBUG "snull: " fmt, ## args)#  else     /* This one for user space */#    define PDEBUG(fmt, args...) fprintf(stderr, fmt, ## args)#  endif#else#  define PDEBUG(fmt, args...) /* not debugging: nothing */#endif#undef PDEBUGG#define PDEBUGG(fmt, args...) /* nothing: it's a placeholder *//* These are the flags in the statusword */#define SNULL_RX_INTR 0x0001#define SNULL_TX_INTR 0x0002/* Default timeout period */#define SNULL_TIMEOUT 5   /* In jiffies */extern struct net_device *snull_devs[];