LddKernelLibraryFunctions < Training2

%SECTION0{name=LddLibraryFunctions}% Kernel library functions

   * linux features standard implementations for various types and functions:
      * linked lists
         * circular, double linked list (_linux/list.h_)
         * klists, more sophisticated list with locking and ref counting (_linux/klist.h_)
      * kfifos (_linux/kfifo.h_)
      * string functions
      * bit and bitmap operations
      * (commandline) parsing
      * crc functions
      * ...

   * documentation?

      <verbatim>
      make htmldocs
      firefox Documentation/DocBook/index.html
      </verbatim>

      -> kernel api

---++ API: linked lists

*type:*

<verbatim>
struct list_head {
       struct list_head *next, *prev;
};
</verbatim>


*Initalize head pointer:*

<verbatim>
struct list_head mempool;
INIT_LIST_HEAD(&mempool);   /* at runtime or ... */
LIST_HEAD(mempool);      /* at compile time */
</verbatim>


*Embedd =struct list_head= in list element:*

<verbatim>
struct mem_chunk {
       unsigned char *ptr;
       int len;
       struct list_head list;
}
</verbatim>

*add element:*
<verbatim>
struct mem_chunk mc;
mc.ptr = this;
mc.len = 128;

list_add(&mc.list, &mempool);
</verbatim>

*remove element:*
<verbatim>
struct list_head myelement = list_del(&mempool.next);
</verbatim>

*find superstructure:*
<verbatim>
mc = list_entry(myelement, struct mem_chunk, list);
</verbatim>



*Functions:*

see _kernel-api_ documentation and _include/list.h_
5.7.6. How to delay execution		1. Denx Training Topics		5.7.8. Userspace kernel communication
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