添加一些关于midi播放的项目

Midi/music-box-nv32-master/nv32lib/common/queue.c

@@ -0,0 +1,124 @@
+/******************************************************************************
+*
+*
+* @brief Implement a first in, first out linked list. 
+*
+*******************************************************************************/
+
+#include "common.h"
+#include "queue.h"
+
+/********************************************************************/
+/* 
+ * Initialize the specified queue to an empty state
+ * 
+ * Parameters:
+ *  q   Pointer to queue structure
+ */
+void
+queue_init(QUEUE *q)
+{
+    q->head = NULL;
+}
+/********************************************************************/
+/* 
+ * Check for an empty queue
+ *
+ * Parameters:
+ *  q       Pointer to queue structure
+ * 
+ * Return Value:
+ *  1 if Queue is empty
+ *  0 otherwise
+ */
+int
+queue_isempty(QUEUE *q)
+{
+    return (q->head == NULL);
+}
+/********************************************************************/
+/* 
+ * Add an item to the end of the queue 
+ *
+ * Parameters:
+ *  q       Pointer to queue structure
+ *  node    New node to add to the queue
+ */
+void
+queue_add(QUEUE *q, QNODE *node)
+{
+    if (queue_isempty(q))
+    {
+        q->head = q->tail = node;
+    }
+    else
+    {
+        q->tail->next = node;
+        q->tail = node;
+    }
+    
+    node->next = NULL;
+}
+
+/********************************************************************/
+/* 
+ * Remove and return first (oldest) entry from the specified queue 
+ *
+ * Parameters:
+ *  q       Pointer to queue structure
+ *
+ * Return Value:
+ *  Node at head of queue - NULL if queue is empty
+ */
+QNODE*
+queue_remove(QUEUE *q)
+{
+    QNODE *oldest;
+    
+    if (queue_isempty(q))
+        return NULL;
+    
+    oldest = q->head;
+    q->head = oldest->next;
+    return oldest;
+}
+/********************************************************************/
+/* 
+ * Peek into the queue and return pointer to first (oldest) entry.
+ * The queue is not modified
+ *
+ * Parameters:
+ *  q       Pointer to queue structure
+ *
+ * Return Value:
+ *  Node at head of queue - NULL if queue is empty
+ */
+QNODE*
+queue_peek(QUEUE *q)
+{
+    return q->head;
+}
+/********************************************************************/
+/* 
+ * Move entire contents of one queue to the other
+ *
+ * Parameters:
+ *  src     Pointer to source queue
+ *  dst     Pointer to destination queue
+ */
+void
+queue_move(QUEUE *dst, QUEUE *src)
+{
+    if (queue_isempty(src))
+        return;
+    
+    if (queue_isempty(dst))
+        dst->head = src->head;
+    else
+        dst->tail->next = src->head;
+
+    dst->tail = src->tail;
+    src->head = NULL;
+    return;
+}
+/********************************************************************/