An Introduction to Linux Device Driver Development - Computer ...

6 Laboratory Exercise #6
device file. Accessing the man pages can be done via the terminal. For example, to view the
man pages on ‘open’, type ‘man open’ in a terminal window.
(b) Within the ‘modules’ directory, create a source file called ‘devtest.c’ and copy the following
starter text into that file:
# i n c l u d e
# i n c l u d e
# i n c l u d e < f c n t l . h>
# i n c l u d e
# i n c l u d e
# i n c l u d e < s t d l i b . h>
i n t main ( ) {
unsigned i n t r e s u l t ;
i n t fd ; / ∗ f i l e d e s c r i p t o r ∗ /
i n t i , j ; / ∗ loop v a r i a b l e s ∗ /
char i n p u t = 0 ;
/ ∗ open d e v i c e f i l e f o r r e a d i n g and w r i t i n g ∗ /
/ ∗ use ”open” t o open ‘ / dev / m u l t i p l i e r ’ ∗ /
/ ∗ h a n d l e e r r o r opening f i l e ∗ /
i f ( fd == −1){
p r i n t f ( ” F a i l e d t o open d e v i c e f i l e !\ n ” ) ;
return −1;
}
while ( i n p u t != ’ q ’ ){ / ∗ c o n t i n u e u n l e s s u s e r e n t e r e d ’ q ’ ∗ /
f o r ( i =0; i