11

The Last Algorithms Course You'll Need/11. Ring Buffer.c

@@ -0,0 +1,127 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#define SIZE 24
+
+typedef int BOOL;
+#define TRUE 1
+#define FALSE 0
+
+typedef struct
+{
+	int head;
+	int tail;
+	int size;
+	int* buffer;
+} RingBufferState;
+
+BOOL init_ring_buffer(int size, RingBufferState* state)
+{
+	if (state == NULL)
+		return FALSE;
+
+	int* buffer = malloc(size * sizeof(int));
+	if (buffer == NULL)
+		return FALSE;
+
+	state->buffer = buffer;
+	state->head = 0;
+	state->tail = 0;
+	state->size = size;
+
+	return TRUE;
+}
+
+BOOL free_ring_buffer(RingBufferState* state)
+{
+	if (state == NULL)
+		return FALSE;
+
+	free(state->buffer);
+	state->buffer = NULL;
+	state->size = 0;
+	state->tail = 0;
+	state->head = 0;
+
+	return TRUE;
+}
+
+BOOL push_to_ring_buffer(int value, RingBufferState* state)
+{
+	if (state == NULL)
+		return FALSE;
+
+	state->buffer[state->head] = value;
+
+	++state->head;
+	if (state->head >= state->size)
+		state->head = 0;
+
+	if (state->head == state->tail)
+		++state->tail;
+
+	return TRUE;
+}
+
+BOOL pop_from_ring_buffer(int* value, RingBufferState* state)
+{
+	if (state == NULL || state->head == state->tail)
+		return FALSE;
+
+	--state->head;
+	if (state->head < 0)
+		state->head = state->size - 1;
+
+	*value = state->buffer[state->head];
+
+	return TRUE;
+}
+
+BOOL print_ring_buffer(RingBufferState* state)
+{
+	if (state == NULL)
+		return FALSE;
+
+	printf("h: %d; t: %d; s: %d\n", state->head, state->tail, state->size);
+	for (int i = 0; i < state->size; ++i)
+	{
+		if (i == state->tail)
+			printf("|");
+		printf("%d ", state->buffer[i]);
+		if (i == state->head)
+			printf("^");
+	}
+	printf("\n");
+
+	return TRUE;
+}
+
+int main()
+{
+	RingBufferState state;
+	init_ring_buffer(SIZE, &state);
+	for (int i = 0; i < SIZE; ++i)
+		push_to_ring_buffer(i, &state);
+	print_ring_buffer(&state);
+	printf("----\n");
+	push_to_ring_buffer(999, &state);
+	push_to_ring_buffer(999, &state);
+	print_ring_buffer(&state);
+	int value = 0;
+	pop_from_ring_buffer(&value, &state);
+	printf("---\n");
+	printf("g: %d\n", value);
+	print_ring_buffer(&state);
+	printf("---\n");
+	push_to_ring_buffer(6969, &state);
+	print_ring_buffer(&state);
+	pop_from_ring_buffer(&value, &state);
+	pop_from_ring_buffer(&value, &state);
+	pop_from_ring_buffer(&value, &state);
+	pop_from_ring_buffer(&value, &state);
+	pop_from_ring_buffer(&value, &state);
+	print_ring_buffer(&state);
+	push_to_ring_buffer(6969, &state);
+	push_to_ring_buffer(6969, &state);
+	print_ring_buffer(&state);
+}