From bd02cca0a3eb7fb8409007a64d44391ec36ed8b5 Mon Sep 17 00:00:00 2001
From: Patrick Stotko <stotko@cs.uni-bonn.de>
Date: Mon, 5 Nov 2018 16:25:45 +0100
Subject: [PATCH] Fix sorting in rare case when no swapping is performed in the
 initial run (every even pair is sorted)

---
 FriedLiver/Source/SiftGPU/SIFTImageManager.cu | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/FriedLiver/Source/SiftGPU/SIFTImageManager.cu b/FriedLiver/Source/SiftGPU/SIFTImageManager.cu
index 06a78299..9b46b7ce 100644
--- a/FriedLiver/Source/SiftGPU/SIFTImageManager.cu
+++ b/FriedLiver/Source/SiftGPU/SIFTImageManager.cu
@@ -104,7 +104,8 @@ void __global__ SortKeyPointMatchesCU_Kernel(
 	__shared__ bool swapped;
 	swapped = true;
 	unsigned int run = 0;
-	while (swapped) {
+	//at least one odd phase is required
+	while (swapped || run < 2) {
 		swapped = false;
 
 		unsigned int idx0 = 2 * tidx + 0;