From 8a41edf24df9a24d4e6e6912d5a21da90ec3c6e1 Mon Sep 17 00:00:00 2001
From: f4exb <f4exb06@gmail.com>
Date: Tue, 14 Jul 2015 00:04:34 +0200
Subject: [PATCH] Scope falling edge trigger

---
 include-gpl/dsp/scopevis.h |  1 +
 sdrbase/dsp/scopevis.cpp   | 22 ++++++++++++++++------
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/include-gpl/dsp/scopevis.h b/include-gpl/dsp/scopevis.h
index 7a44a3482..ec59f0f27 100644
--- a/include-gpl/dsp/scopevis.h
+++ b/include-gpl/dsp/scopevis.h
@@ -72,6 +72,7 @@ private:
 	TriggerChannel m_triggerChannel;
 	Real m_triggerLevel;
 	bool m_triggerPositiveEdge;
+	bool m_armed;
 	int m_sampleRate;
 
 	bool triggerCondition(SampleVector::const_iterator& it);
diff --git a/sdrbase/dsp/scopevis.cpp b/sdrbase/dsp/scopevis.cpp
index 87f9ad69e..fe2eaccc6 100644
--- a/sdrbase/dsp/scopevis.cpp
+++ b/sdrbase/dsp/scopevis.cpp
@@ -16,6 +16,7 @@ ScopeVis::ScopeVis(GLScope* glScope) :
 	m_triggerChannel(TriggerFreeRun),
 	m_triggerLevel(0.0),
 	m_triggerPositiveEdge(true),
+	m_armed(false),
 	m_sampleRate(0)
 {
 }
@@ -48,16 +49,25 @@ void ScopeVis::feed(SampleVector::const_iterator begin, SampleVector::const_iter
 		}
 		else
 		{
-			if(m_triggerState == Untriggered) {
-				while(begin < end) {
-					if (triggerCondition(begin)) {
-						m_triggerState = Triggered;
-						break;
+			if(m_triggerState == Untriggered)
+			{
+				while(begin < end)
+				{
+					if (triggerCondition(begin) ^ !m_triggerPositiveEdge) {
+						if (m_armed) {
+							m_triggerState = Triggered;
+							m_armed = false;
+							break;
+						}
+					}
+					else {
+						m_armed = true;
 					}
 					++begin;
 				}
 			}
-			if(m_triggerState == Triggered) {
+			if(m_triggerState == Triggered)
+			{
 				int count = end - begin;
 				if(count > (int)(m_trace.size() - m_fill))
 					count = m_trace.size() - m_fill;