Start adding a message queue.

message.c

@@ -0,0 +1,147 @@
+/*  SSNES - A Super Nintendo Entertainment System (SNES) Emulator frontend for libsnes.
+ *  Copyright (C) 2010 - Hans-Kristian Arntzen
+ *
+ *  Some code herein may be based on code found in BSNES.
+ * 
+ *  SSNES is free software: you can redistribute it and/or modify it under the terms
+ *  of the GNU General Public License as published by the Free Software Found-
+ *  ation, either version 3 of the License, or (at your option) any later version.
+ *
+ *  SSNES is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ *  PURPOSE.  See the GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with SSNES.
+ *  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "message.h"
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+struct queue_elem
+{
+   unsigned duration;
+   unsigned prio;
+   char *msg;
+};
+
+struct msg_queue
+{
+   struct queue_elem **elems;
+   size_t ptr;
+   size_t size;
+   char *tmp_msg;
+};
+
+msg_queue_t *msg_queue_new(size_t size)
+{
+   msg_queue_t *queue = calloc(1, sizeof(*queue));
+   if (!queue)
+      return NULL;
+
+   queue->size = size + 1;
+   queue->elems = calloc(queue->size, sizeof(struct queue_elem*)); 
+   // Allocate one extra for scratch space when finding lowest prio elem.
+
+   if (!queue->elems)
+   {
+      free(queue);
+      return NULL;
+   }
+   queue->ptr = 1;
+   return queue;
+}
+
+void msg_queue_free(msg_queue_t *queue)
+{
+   for (size_t i = 1; i < queue->ptr; i++)
+   {
+      if (queue->elems[i])
+      {
+         free(queue->elems[i]->msg);
+         free(queue->elems[i]);
+      }
+   }
+   free(queue->elems);
+   free(queue->tmp_msg);
+   free(queue);
+}
+
+void msg_queue_push(msg_queue_t *queue, const char *msg, unsigned prio, unsigned duration)
+{
+   struct queue_elem *new_elem = calloc(1, sizeof(struct queue_elem));
+   new_elem->prio = prio;
+   new_elem->duration = duration;
+   new_elem->msg = msg ? strdup(msg) : NULL;
+
+   queue->elems[queue->ptr] = new_elem;
+   size_t tmp_ptr = queue->ptr++;
+
+   while (tmp_ptr > 1)
+   {
+      struct queue_elem *parent = queue->elems[tmp_ptr >> 1];
+      struct queue_elem *child = queue->elems[tmp_ptr];
+
+      if (child->prio <= parent->prio)
+         break;
+      else
+      {
+         queue->elems[tmp_ptr >> 1] = child;
+         queue->elems[tmp_ptr] = parent;
+      }
+      tmp_ptr >>= 1;
+   }
+}
+
+const char *msg_queue_pull(msg_queue_t *queue)
+{
+   if (queue->ptr == 1) // Nothing in queue. :(
+      return NULL;
+
+   struct queue_elem *front = queue->elems[1];
+   front->duration--;
+   if (front->duration > 0)
+      return front->msg;
+   else
+   {
+      queue->tmp_msg = front->msg;
+      front->msg = NULL;
+
+      struct queue_elem *front = queue->elems[1];
+      struct queue_elem *last = queue->elems[--queue->ptr];
+      queue->elems[1] = last;
+      free(front);
+
+      size_t tmp_ptr = 1;
+      for (;;)
+      {
+         bool left = (tmp_ptr * 2 <= queue->ptr) && (queue->elems[tmp_ptr] < queue->elems[tmp_ptr * 2]);
+         bool right = (tmp_ptr * 2 + 1 <= queue->ptr) && (queue->elems[tmp_ptr] < queue->elems[tmp_ptr * 2 + 1]);
+
+         if (!left && !right)
+            break;
+
+         size_t switch_index = tmp_ptr;
+         if (left && !right)
+            switch_index <<= 1;
+         else if (right && !left)
+            switch_index += switch_index + 1;
+         else
+         {
+            if (queue->elems[tmp_ptr * 2] >= queue->elems[tmp_ptr * 2 + 1])
+               switch_index <<= 1;
+            else
+               switch_index += switch_index + 1;
+         }
+         struct queue_elem *parent = queue->elems[tmp_ptr];
+         struct queue_elem *child = queue->elems[switch_index];
+         queue->elems[tmp_ptr] = child;
+         queue->elems[switch_index] = parent;
+         tmp_ptr = switch_index;
+      }
+
+      return queue->tmp_msg;
+   }
+}

message.h

@@ -0,0 +1,38 @@
+/*  SSNES - A Super Nintendo Entertainment System (SNES) Emulator frontend for libsnes.
+ *  Copyright (C) 2010 - Hans-Kristian Arntzen
+ *
+ *  Some code herein may be based on code found in BSNES.
+ * 
+ *  SSNES is free software: you can redistribute it and/or modify it under the terms
+ *  of the GNU General Public License as published by the Free Software Found-
+ *  ation, either version 3 of the License, or (at your option) any later version.
+ *
+ *  SSNES is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ *  PURPOSE.  See the GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with SSNES.
+ *  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#ifndef __SSNES_MSG_QUEUE_H
+#define __SSNES_MSG_QUEUE_H
+
+#include <stddef.h>
+
+typedef struct msg_queue msg_queue_t;
+
+// Creates a message queue with maximum size different messages. Returns NULL if allocation error.
+msg_queue_t *msg_queue_new(size_t size);
+
+// Higher prio is... higher prio :) Duration is how many times a message can be pulled from queue before it vanishes. (E.g. show a message for 3 seconds @ 60fps = 180 duration). 
+
+void msg_queue_push(msg_queue_t *queue, const char *msg, unsigned prio, unsigned duration);
+
+// Pulls highest prio message in queue. Returns NULL if no message in queue.
+const char *msg_queue_pull(msg_queue_t *queue);
+
+void msg_queue_free(msg_queue_t *queue);
+
+#endif