# HG changeset patch
# User SeanHalle
# Date 1289477941 28800
# Node ID 3134d8a1e8e39722ab37726cd3a54e34de66cf83
# Parent  3562716ebdbde0fc5e1d23d91cdde57ca2c62caa
added pushPrivQ -- treats Q as stack, pushed elem is first out

diff -r 3562716ebdbd -r 3134d8a1e8e3 PrivateQueue.c
--- a/PrivateQueue.c	Thu Nov 04 17:54:08 2010 -0700
+++ b/PrivateQueue.c	Thu Nov 11 04:19:01 2010 -0800
@@ -156,6 +156,39 @@
    return FALSE;
  }
 
+/*Treats queue as a stack -- no matter contents, if read done right after
+ * a push, then the pushed item is what comes out.
+ * Expands the queue size automatically when it's full.
+ */
+void
+pushPrivQ( void * in, PrivQueueStruc* Q )
+ {
+   void **startOfData = Q->startOfData;
+   void **endOfData   = Q->endOfData;
+
+   void **insertPos  = Q->insertPos;
+   void **extractPos = Q->extractPos;
+
+tryAgain:
+      //Full? (insert is just below extract when full)
+   if( extractPos - insertPos != 1 &&
+       !(insertPos == endOfData && extractPos == startOfData))
+    {    //insert -- but go backwards, inserting at read position then
+         // move read pos backwards
+      *(Q->extractPos) = in;
+      if( extractPos == startOfData ) //write new pos exactly once, correctly
+       { Q->extractPos = endOfData;   //can't overrun then fix it 'cause
+       }                              // other thread might read bad pos
+      else
+       { Q->extractPos--;
+       }
+      return;
+    }
+      //Q is full
+   enlargePrivQ( Q );
+   goto tryAgain;
+ }
+
 void
 freePrivQ( PrivQueueStruc *Q )
  {
diff -r 3562716ebdbd -r 3134d8a1e8e3 PrivateQueue.h
--- a/PrivateQueue.h	Thu Nov 04 17:54:08 2010 -0700
+++ b/PrivateQueue.h	Thu Nov 11 04:19:01 2010 -0800
@@ -8,7 +8,6 @@
 #ifndef _PRIVATE_QUEUE_H
 #define	_PRIVATE_QUEUE_H
 
-#include <pthread.h>
 #include "../VMS_primitive_data_types.h"
 
 #define TRUE     1
@@ -33,7 +32,7 @@
 int32            writeIfSpacePrivQ( void * in, PrivQueueStruc* Q ); //return
                     // false when full
 int32            numInPrivQ( PrivQueueStruc *Q );
-
+void             pushPrivQ( void * in, PrivQueueStruc* Q );
 
 #endif	/* _PRIVATE_QUEUE_H */