Figure is a listing of code intended for use on the eCos kernel.

a. Explain the operation of the code. Assume thread B begins execution first and thread A begins to execute after some event occurs.
b. What would happen if the mutex unlock and wait code execution in the call to cyg_cond_wait, on line 30, were not atomic?
c. Why is the while loop on line 26 needed?

Transcribed Image Text:

1 unsigned char buffer_empty true; суд mutex t mut cond var; 3 cyg cond-t cond_var; 5 void thread af cyg_ addrword t index ) 7 while 1 run this thread forever // acquire data into the buffer... 10 // there is data in the buffer now 12 13 14 15 16 17 18 19 20 21 22 void thread b cyg addrword t index ) 23 24 while 1 /run this thread forever 25 26 27 28 29 3 0 31 32 buffer-empty false; cyg mutex lock f &mut cond var cyg cond signal cond var ) суд.-mutex-unlock( &mut-cond-var ); суд, mutex-lock ( &mut. Cond-var while ( buffer_empty true) cyg-cond-wait( &cond-var ); ); // get the buffer data. 34 35 36 37 38 39 4 0 // set flag to indicate the data in the buffer has been processed buffer empty truei cyg mutex unlock ( &mut cond var // process the data in the buffer 4 2 43