How to Write a Writer Routine.

Sanny Singh — Wed, 16 Dec 2015 06:51:16 +0000

In the char driver We write the Write Routine. This write routine is mapped in struct file operations . We use copy_from_user macro. this macro has three arguments. first is void* to second is const void* __user form and last argument is how many char have to write.

first malloc the sqset then malloc sqset->data and at last create qsetarray. Then malloc qsetarry member one by one and write the data by using copy_from_user macro.

Data Structures With C

Sanny Singh — Fri, 20 Nov 2015 05:14:37 +0000

In data structure padding some allocate space is free this case is called is padding. Like a example is as as the structure we take three variable that is int,char,float. This is structure allocate 12 byte space. At the architecture of process it read 1 word at the time.(for 32 bit process 4 byte per word and for 64 bit process 8 byte per word).

struct emblogic

{ int; char;float}blog;

At this avoid this structure padding in C !

we used

#pragma pack(1)

After that the size of structure this structure is only 9 byte.

My question is where is define this pragma pack(1) (like as include directory path is /usr/include/ ). And how it works??

EmbLogic » Sanny Singh

How to Write a Writer Routine.

Data Structures With C