SE-352

Embedded Software

Lab Assignment 3    (Due Friday, March 16)

Do the following on top of your Lab 2 work:

   1)  Implement a progStart function, which spawns one insert task and three
        lookup tasks, with the lookup tasks spawned 200 clock ticks later than
        the insert task is.

 

   2)  The insert task keeps on inserting new nodes to the trees.
        -- Each time it inserts a new node, it sleeps for 10 clock ticks.
        -- The key value of a new node is random number generated according to the
             following recursion algorithm:

                y_k+1 = (a * y_k + b) % m

                keyValue = 1000 + (y_k+1 % n)

             where a = 56789, b = 12345, y₀ = 12345,  m = 32768, n = 8999.
        -- All new item price is 9.99.
        -- Based on the above algorithm, y₁ = 1190, y₂ = 23639,  ... and the first item is
            (391, 9.99), the second item (365, 9.99), ...

   3)  The three lookup tasks inquire item prices periodically. The period of the first
        task is 90 ticks, the second one 120 ticks and the third one 150 ticks. Each task
        does the inquiry independently on items according to the order that they are
        generated by the insert task. In other words, each lookup task follows the same
        algorithm as shown in 2) to decide the item IDs to inquire. When an item is
        inquired, display:
        -- the lookup task ID,
        -- the item ID and item price.

 

   4)  Use semaphores to control access to the trees. Here are the polices:

         -- The lookup tasks can access the trees simultaneously.
         -- The insert task always requires exclusive access.
         -- The first lookup task has to compete for the access with the insert task.
         -- As long as a lookup task holds the trees, another lookup task will get
             access to the trees automatically regardless of whether the insert task is
             is waiting to access the trees or not. 

 

   5)  Implement a progStop function, which is used to terminate all tasks, display
        all trees and then erase all trees.

On the due day, you need to send me a softcopy of your source code.

Note: Call taskDelay(n) to delay a task for executing by n ticks.