From 4d83f7631211b0d828c7d2ea1276e8e3049e901c Mon Sep 17 00:00:00 2001
From: gnawali <gnawali>
Date: Wed, 31 Oct 2007 22:53:01 +0000
Subject: [PATCH] get etx now returns etx for the path to the root instead of
 etx from the current parent to the root

---
 tos/lib/net/ctp/CtpInfo.nc           | 2 +-
 tos/lib/net/ctp/CtpRoutingEngineP.nc | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/tos/lib/net/ctp/CtpInfo.nc b/tos/lib/net/ctp/CtpInfo.nc
index 57c275ef..80745976 100644
--- a/tos/lib/net/ctp/CtpInfo.nc
+++ b/tos/lib/net/ctp/CtpInfo.nc
@@ -45,7 +45,7 @@ interface CtpInfo {
    * through the current parent.  The pointer is allocated by the
    * caller.  If the parent is invalid, return FAIL (no info).  The
    * caller MUST NOT use the value in parent if the return is not
-   * SUCCESS.
+   * SUCCESS. Calling getEtx at the root will set the etx argument to 0.
    */
   
   command error_t getEtx(uint16_t* etx);
diff --git a/tos/lib/net/ctp/CtpRoutingEngineP.nc b/tos/lib/net/ctp/CtpRoutingEngineP.nc
index a2d935f8..5a595341 100644
--- a/tos/lib/net/ctp/CtpRoutingEngineP.nc
+++ b/tos/lib/net/ctp/CtpRoutingEngineP.nc
@@ -548,7 +548,12 @@ implementation {
             return FAIL;
         if (routeInfo.parent == INVALID_ADDR)    
             return FAIL;
-        *etx = routeInfo.etx;
+	if (state_is_root == 1) {
+	  *etx = 0;
+	} else {
+	  // path etx = etx(parent) + etx(link to the parent)
+	  *etx = routeInfo.etx + evaluateEtx(call LinkEstimator.getLinkQuality(routeInfo.parent));
+	}
         return SUCCESS;
     }
 
-- 
2.39.2