From 9d0ee6969c457bb256dbb5e0d6274097e497459c Mon Sep 17 00:00:00 2001
From: Jean Pierre Cimalando <jp-dev@inbox.ru>
Date: Mon, 28 Sep 2020 21:49:20 +0200
Subject: [PATCH] flexEG: allow release to bypass the pre-sustain stages It
 makes the EG equivalent to ARIA in case of early release.

---
 src/sfizz/FlexEnvelope.cpp | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/sfizz/FlexEnvelope.cpp b/src/sfizz/FlexEnvelope.cpp
index c9302c0b..3a7402dd 100644
--- a/src/sfizz/FlexEnvelope.cpp
+++ b/src/sfizz/FlexEnvelope.cpp
@@ -160,12 +160,24 @@ void FlexEnvelope::Impl::process(absl::Span<float> out)
         }
 
         // Perform stage transitions
-        const bool isReleased = isReleased_;
-        while ((!stageSustained_ && currentTime_ >= stageTime_) ||
-               (stageSustained_ && isReleased)) {
-            // If stage is of zero duration, immediate transition to level
-            if (!stageSustained_ && stageTime_ == 0)
+        if (isReleased_) {
+            // on release, fast forward past the sustain stage
+            const unsigned sustainStage = desc.sustain;
+            while (currentStageNumber_ <= sustainStage) {
+                if (!advanceToNextStage()) {
+                    out.remove_prefix(frameIndex);
+                    fill(out, 0.0f);
+                    return;
+                }
+            }
+        }
+        while (!stageSustained_ && currentTime_ >= stageTime_) {
+            // advance through completed timed stages
+            ASSERT(isReleased_ || !stageSustained_);
+            if (stageTime_ == 0) {
+                // if stage is of zero duration, immediate transition to level
                 currentLevel_ = stageTargetLevel_;
+            }
             if (!advanceToNextStage()) {
                 out.remove_prefix(frameIndex);
                 fill(out, 0.0f);