11.6. Quick Reference

The following symbols were introduced in this chapter:

#include <linux/types.h>

typedef u8;

typedef u16;

typedef u32;

typedef u64;

Types guaranteed to be 8-, 16-, 32-, and 64-bit unsigned integer values. The equivalent signed types exist as well. In user space, you can refer to the types as _ _u8, _ _u16, and so forth.

#include <asm/page.h>

PAGE_SIZE

PAGE_SHIFT

Symbols that define the number of bytes per page for the current architecture and the number of bits in the page offset (12 for 4-KB pages and 13 for 8-KB pages).

#include <asm/byteorder.h>

_ _LITTLE_ENDIAN

_ _BIG_ENDIAN

Only one of the two symbols is defined, depending on the architecture.

#include <asm/byteorder.h>

u32 _ _cpu_to_le32 (u32);

u32 _ _le32_to_cpu (u32);

Functions that convert between known byte orders and that of the processor. There are more than 60 such functions; see the various files in include/linux/byteorder/ for a full list and the ways in which they are defined.

#include <asm/unaligned.h>

get_unaligned(ptr);

put_unaligned(val, ptr);

Some architectures need to protect unaligned data access using these macros. The macros expand to normal pointer dereferencing for architectures that permit you to access unaligned data.

#include <linux/err.h>

void *ERR_PTR(long error);

long PTR_ERR(const void *ptr);

long IS_ERR(const void *ptr);

Functions allow error codes to be returned by functions that return a pointer value.

#include <linux/list.h>

list_add(struct list_head *new, struct list_head *head);

list_add_tail(struct list_head *new, struct list_head *head);

list_del(struct list_head *entry);

list_del_init(struct list_head *entry);

list_empty(struct list_head *head);

list_entry(entry, type, member);

list_move(struct list_head *entry, struct list_head *head);

list_move_tail(struct list_head *entry, struct list_head *head);

list_splice(struct list_head *list, struct list_head *head);

Functions that manipulate circular, doubly linked lists.

list_for_each(struct list_head *cursor, struct list_head *list)

list_for_each_prev(struct list_head *cursor, struct list_head *list)

list_for_each_safe(struct list_head *cursor, struct list_head *next, struct

list_head *list)

list_for_each_entry(type *cursor, struct list_head *list, member)

list_for_each_entry_safe(type *cursor, type *next struct list_head *list,

member)

Convenience macros for iterating through linked lists.