Add new code

Signed-off-by: Carlos Maiolino <[email protected]>

1 files changed, 166 insertions, 0 deletions

diff --git a/Algorithms/queue_static.c b/Algorithms/queue_static.c
new file mode 100644
index 0000000..5124a01
--- /dev/null
+++ b/Algorithms/queue_static.c
@@ -0,0 +1,166 @@
+#include <stdio.h>
+
+#define QUEUE_SIZE 10
+
+/*
+ * Simple queue algorithm implementation
+ *
+ * tail will always point to the next available slot
+ */
+struct queue {
+	int data[QUEUE_SIZE];
+	int head;
+	int tail;
+};
+
+int queue_empty(struct queue *Q)
+{
+	return Q->head == Q->tail;
+}
+
+/*
+ * Queue is full when:
+ * tail + 1 == HEAD or
+ * TAIL == QUEUE_SIZE - 1 and HEAD == 0
+ */
+int queue_full(struct queue *Q)
+{
+	if (((Q->tail + 1) == Q->head) ||
+	    ((Q->tail == (QUEUE_SIZE - 1)) && (Q->head == 0)))
+		return 1;
+	else
+		return 0;
+}
+
+int queue_push(struct queue *Q, int value)
+{
+	if (queue_full(Q)) {
+	    printf("Queue is full, avoiding overflow\n");
+	    return 0;
+	}
+
+	Q->data[Q->tail] = value;
+
+	if (Q->tail == (QUEUE_SIZE - 1))
+		Q->tail = 0;
+	else
+		Q->tail++;
+
+	return value;
+
+}
+
+/* FIXME: function return 0 in case of failure, should return something
+ *	  else, once 0 is a valid value to the queue
+ */
+int queue_pop(struct queue *Q)
+{
+	int value = 0;
+
+	if (queue_empty(Q)) {
+		printf("Queue is empty, avoiding underflow\n");
+		return value;
+	}
+
+	value = Q->data[Q->head];
+
+	if (Q->head == (QUEUE_SIZE - 1))
+		Q->head = 0;
+	else
+		Q->head++;
+
+	return value;
+}
+
+void print_queue(struct queue *Q)
+{
+	int i = Q->head;
+	int pos = 1;
+
+	if (queue_empty(Q)) {
+		printf("Nothing to print, queue is empty\n");
+		return;
+	}
+
+	printf(" Pos  | Tail \n");
+	for (;;) {
+		printf(" %d | %d \n", pos, Q->data[i]);
+
+		if (i == (QUEUE_SIZE - 1))
+			i = 0;
+		else
+			i++;
+		pos++;
+
+		if (i == Q->tail)
+			break;
+	}
+}
+
+void debug_queue(struct queue *Q)
+{
+	int i;
+
+	for (i = 0; i < QUEUE_SIZE; i++) {
+		printf("| %d | ", Q->data[i]);
+
+		if (i == Q->head)
+			printf("<-- HEAD ");
+		if (i == Q->tail)
+			printf("<-- TAIL");
+		printf("\n");
+	}
+}
+
+int main(void)
+{
+	struct queue my_queue;
+	int i, val;
+	char cmd;
+
+	/* Init queue */
+	my_queue.head = 0;
+	my_queue.tail = 0;
+	for (i = 0; i < QUEUE_SIZE; i++)
+		my_queue.data[i] = 0;
+
+	while (1) {
+		printf("Select an option: ");
+		scanf(" %c", &cmd);
+
+		switch (cmd) {
+			case 'a':
+				printf("Value to add: ");
+				scanf(" %d", &val);
+				queue_push(&my_queue, val);
+				break;
+			case 'p':
+				queue_pop(&my_queue);
+				break;
+			case 'd':
+				debug_queue(&my_queue);
+				break;
+			case 'l':
+				print_queue(&my_queue);
+				break;
+			default:
+				printf("Invalid option\n");
+				printf("a = add, p = pop, d = debug, l = print\n");
+		}
+	}
+
+	return 0;
+}
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