The system used a shared buffer that would accept blocks of characters from a measurement process P1 and forward blocks of data to the output process, P2. The designer has written the following routines, one for P1 and one for P2.
full = 0
max = buffer size
p1Generate( ) p2Transmit( )
{ {
P2
P1
head
buffer
while (full < max) while (full > 0)
{ {
buffer(head) = anItem; anItem = buffer(head);
(head = head + 1) mod max; (head = head – 1) mod max;
full++ ; full–;
} }
} }
Occasionally the system either looses data or forwards garbage data.
Can you explain why?
Please propose (in detail) a way to fix the problem. Modify the existing code as necessary.
Please show how your design solves the problem.
