Linux驱动知识：内核中常用的数据类型

#include 
typedef u8;
typedef u16;
typedef u32;
typedef u64;

The equivalent signed types exist as well. In user space, you can refer to the types as __u8, _ _u16, and so forth.

 

#include

PAGE_SIZE    //未必是4K
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 
__LITTLE_ENDIAN
__BIG_ENDIAN

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

 

#include 
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 ininclude/linux/byteorder/ for a full list and the ways in which they are defined.

 

#include 
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.

有的平台上在非对齐的位置存取相应数据（比如在4的非整数倍地址上访问u32）会有问题，有的平台是通过产生异常并在异常处理中进行读写，极大降低了性能。

 

#include 
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 
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.

 

 

转载于:https://www.cnblogs.com/realplay/p/10913658.html