Initial commit

util/queue.c

@@ -0,0 +1,55 @@
+
+#include "queue.h"
+#include "../runtime/stdio.h"
+
+
+void queue_InitBuffered(queue *q, void *buffer, uintptr_t size) {
+	q->data = q->begin = q->end = buffer;
+	q->size                     = size;
+	q->count                    = 0;
+}
+
+void queue_PushByte(queue *q, const uint8_t b) {
+	if (q->count == q->size) { // no more space
+		io_Printf("queue_PushByte: full[%llu bytes], discarding byte 0x%x\n", q->size, b);
+		return;
+	}
+
+	q->count++;
+	*((uint8_t *)(q->end++)) = b;
+	if (q->end == q->data + q->size)
+		q->end = q->data; // out of the buffer: wrap around
+}
+
+uint8_t queue_PopByte(queue *q) {
+	if (q->count == 0) {
+		io_WriteConsoleASCII("queue_PopByte: poping an empty queue\n");
+		return 0;
+	}
+
+	q->count--;
+	uint8_t data = *((uint8_t *)(q->begin++));
+	if (q->begin == q->data + q->size)
+		q->begin = q->data; // wrap around
+	return data;
+}
+
+uint8_t queue_TopByte(queue *q) {
+	if (q->count == 0) {
+		io_WriteConsoleASCII("queue_TopByte: accessing an empty queue\n");
+		return 0;
+	}
+	return *((uint8_t *)q->begin);
+}
+
+bool queue_Empty(queue *q) {
+	return q->count == 0;
+}
+
+uintptr_t queue_Size(queue *q) {
+	return q->count;
+}
+
+uintptr_t queue_Space(queue *q) {
+	return q->size - q->count;
+}

util/queue.h

@@ -0,0 +1,42 @@
+#pragma once
+
+#include "../main.h"
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+typedef struct {
+	void *    data;        // the data buffer
+	uintptr_t size;        // size of data buffer
+	void *    begin, *end; // begin and past-the-end for in-queue data
+	uintptr_t count;       // number of in-queue bytes
+} queue;
+
+// initialize a queue with a existing buffer
+void queue_InitBuffered(queue *q, void *buffer, uintptr_t size);
+
+// writes one byte to the queue, discarding if full
+void queue_PushByte(queue *q, const uint8_t b);
+
+// pops one byte from the front of the queue, returning it
+uint8_t queue_PopByte(queue *q);
+
+// return the byte at the front of the queue
+uint8_t queue_FrontByte(queue *q);
+
+// tells if the queue is empty
+bool queue_Empty(queue *q);
+
+// returns the number of bytes in the queue
+uintptr_t queue_Size(queue *q);
+
+// returns the empty space left at the end of the queue
+uintptr_t queue_Space(queue *q);
+
+
+#ifdef __cplusplus
+}
+#endif