From d6c5529247d326967962895b34606f2b1e2874ca Mon Sep 17 00:00:00 2001
From: Stefan Wahren <info@lategoodbye.de>
Date: Wed, 3 Oct 2012 23:01:44 +0200
Subject: [PATCH] new function mbus_frame_direction to get the direction of a
 frame (slave to master or vice versa) extended mbus_frame_data_parse to check
 the direction of a frame

---
 mbus/mbus-protocol.c | 41 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 37 insertions(+), 4 deletions(-)

diff --git a/mbus/mbus-protocol.c b/mbus/mbus-protocol.c
index 59736e9..dee306e 100755
--- a/mbus/mbus-protocol.c
+++ b/mbus/mbus-protocol.c
@@ -300,6 +300,19 @@ mbus_frame_type(mbus_frame *frame)
     return -1;
 }
 
+//------------------------------------------------------------------------------
+/// Return the M-Bus frame direction 
+//------------------------------------------------------------------------------
+int
+mbus_frame_direction(mbus_frame *frame)
+{
+    if (frame)
+    {
+        return (frame->control & MBUS_CONTROL_MASK_DIR);
+    }
+    return -1;
+}
+
 //------------------------------------------------------------------------------
 /// Verify that parsed frame is a valid M-bus frame. 
 //
@@ -2713,7 +2726,23 @@ mbus_data_variable_parse(mbus_frame *frame, mbus_data_variable *data)
 int
 mbus_frame_data_parse(mbus_frame *frame, mbus_frame_data *data)
 {
-    if (frame && data)
+    char direction;
+
+    if (frame == NULL)
+    {
+        snprintf(error_str, sizeof(error_str), "Got null pointer to frame.");
+        return -1;
+    }
+    
+    if (data == NULL)
+    {
+        snprintf(error_str, sizeof(error_str), "Got null pointer to data.");
+        return -1;
+    }
+    
+    direction = (frame->control & MBUS_CONTROL_MASK_DIR);
+    
+    if (direction == MBUS_CONTROL_MASK_DIR_S2M)
     {
         if (frame->control_information == MBUS_CONTROL_INFO_ERROR_GENERAL)
         {
@@ -2761,9 +2790,13 @@ mbus_frame_data_parse(mbus_frame *frame, mbus_frame_data *data)
             return -1;
         }
     }
-    
-    snprintf(error_str, sizeof(error_str), "Got null pointer to frame or data.");
-
+    else
+    { 
+        snprintf(error_str, sizeof(error_str), "Wrong direction in frame (master to slave)");
+            
+        return -1;
+    }
+        
     return -1;
 }