C Queue Memory & False Overflow Lab

Physical Memory Buffer & Registers MODE: LINEAR_ARRAY

            Address: 0x7ffd0a0 (Contiguous 4-byte int array)
            isFull() check: rear == MAX_SIZE - 1
          

q->front

q->rear

isEmpty()

false

isFull()

false

Initial State: Items ['A', 'B', 'C'] queued. Front = 0 ('A'), Rear = 2 ('C'). Slots 3 & 4 are uninitialized.

Active C Implementation queue_ops.c

Circular Ring Modulo Geometry & Pointer Math Modulo Index: (rear + 1) % 5

1. OS Round-Robin CPU Scheduler Time-Slice: 10ms

OS manages ready processes in a FIFO queue. The running task gets a time-slice, dequeues, and if unfinished, enqueues back to the rear.

          CPU Idle. Ready tasks in FIFO queue.
        

2. Breadth-First Search (BFS) Explorer FIFO Layer Walk

BFS explores nodes level-by-level using a FIFO queue to guarantee shortest path exploration order.

Queue: [0]

Visited: 0

Trace the saved watermark counting rules and fixture limits

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Read the explanation

The saved queue lab has five array slots and starts with A, B and C at indices zero through two. Three occupied slots leave two unused slots. Both bars show counts at one hundred fifty pixels per slot. Its linear-full check compares rear to size minus one, not the number of live elements. After freeing earlier slots while rear remains four, that rule still reports full: the source calls this false overflow. Circular enqueue advances rear by one modulo five. At rear four the next index is zero. In the false-overflow example front is three, so index zero is available and does not collide with front. Both bars show the illustrative current rear four and front three at one hundred twenty pixels per index unit. The full check tests whether next rear equals front; an empty queue uses front minus one as a separate condition. Follow registers and live memory together. Its round-robin illustration dequeues the first task and subtracts a fixed ten millisecond slice. A thirty-millisecond task then has twenty remaining and is appended to the rear. Both bars show assigned remaining work at eighteen pixels per millisecond. When remaining work becomes zero it is removed permanently. This is a scheduling demonstration, not measured CPU execution. The same first-in first-out principle drives the breadth-first traversal queue.