From c9d31d6e5870cf95861f3411b8cb78d26aab9c95 Mon Sep 17 00:00:00 2001
From: Paul <baconpaul@users.noreply.github.com>
Date: Mon, 26 Aug 2024 14:07:44 -0400
Subject: [PATCH] Make findZone non-allocating (#1191)

Closes #1146
---
 src/engine/engine.h                   | 16 +++++++++-------
 src/engine/engine_voice_responder.cpp | 17 ++++++++---------
 2 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/src/engine/engine.h b/src/engine/engine.h
index f42aca7d..14cf4f89 100644
--- a/src/engine/engine.h
+++ b/src/engine/engine.h
@@ -129,11 +129,10 @@ struct Engine : MoveableOnly<Engine>, SampleRateSupport
         int16_t key{-1};
         int32_t noteid{-1};
     };
-    std::vector<pathToZone_t> findZone(int16_t channel, int16_t key, int32_t noteId,
-                                       int16_t velocity)
+    size_t findZone(int16_t channel, int16_t key, int32_t noteId, int16_t velocity,
+                    std::array<pathToZone_t, maxVoices> &res)
     {
-        // TODO: This allocates which is a bummer
-        std::vector<pathToZone_t> res;
+        size_t idx{0};
         for (const auto &[pidx, part] : sst::cpputils::enumerate(*patch))
         {
             if (!part->configuration.mute &&
@@ -147,14 +146,15 @@ struct Engine : MoveableOnly<Engine>, SampleRateSupport
                         if (zone->mapping.keyboardRange.includes(key) &&
                             zone->mapping.velocityRange.includes(velocity))
                         {
-                            res.push_back(
-                                {(size_t)pidx, (size_t)gidx, (size_t)zidx, channel, key, noteId});
+                            res[idx] = {(size_t)pidx, (size_t)gidx, (size_t)zidx,
+                                        channel,      key,          noteId};
+                            idx++;
                         }
                     }
                 }
             }
         }
-        return res;
+        return idx;
     }
 
     tuning::MidikeyRetuner midikeyRetuner;
@@ -168,6 +168,8 @@ struct Engine : MoveableOnly<Engine>, SampleRateSupport
     struct VoiceManagerResponder
     {
         Engine &engine;
+        std::array<pathToZone_t, maxVoices> findZoneWorkingBuffer;
+
         VoiceManagerResponder(Engine &e) : engine(e) {}
 
         std::function<void(voice::Voice *)> voiceEndCallback{nullptr};
diff --git a/src/engine/engine_voice_responder.cpp b/src/engine/engine_voice_responder.cpp
index 0b5431eb..3651ebe1 100644
--- a/src/engine/engine_voice_responder.cpp
+++ b/src/engine/engine_voice_responder.cpp
@@ -35,9 +35,10 @@ int32_t Engine::VoiceManagerResponder::voiceCountForInitializationAction(
 {
     // TODO: We can optimize this so we don't have to find twice in the future
     auto useKey = engine.midikeyRetuner.remapKeyTo(channel, key);
-    auto nts = engine.findZone(channel, useKey, noteId, std::clamp((int)(velocity * 128), 0, 127));
+    auto nts = engine.findZone(channel, useKey, noteId, std::clamp((int)(velocity * 128), 0, 127),
+                               findZoneWorkingBuffer);
 
-    return nts.size();
+    return nts;
 }
 
 int32_t Engine::VoiceManagerResponder::initializeMultipleVoices(
@@ -45,11 +46,12 @@ int32_t Engine::VoiceManagerResponder::initializeMultipleVoices(
     uint16_t channel, uint16_t key, int32_t noteId, float velocity, float retune)
 {
     auto useKey = engine.midikeyRetuner.remapKeyTo(channel, key);
-    auto nts = engine.findZone(channel, useKey, noteId, std::clamp((int)(velocity * 128), 0, 127));
+    auto nts = engine.findZone(channel, useKey, noteId, std::clamp((int)(velocity * 128), 0, 127),
+                               findZoneWorkingBuffer);
 
-    int idx{0};
-    for (const auto &path : nts)
+    for (auto idx = 0; idx < nts; ++idx)
     {
+        const auto &path = findZoneWorkingBuffer[idx];
         auto &z = engine.zoneByPath(path);
         auto nbSampleLoadedInZone = z->getNumSampleLoaded();
 
@@ -64,7 +66,6 @@ int32_t Engine::VoiceManagerResponder::initializeMultipleVoices(
                 v->attack();
             }
             voiceInitWorkingBuffer[idx] = v;
-            idx++;
         }
         else if (z->sampleData.variantPlaybackMode == Zone::UNISON)
         {
@@ -79,7 +80,6 @@ int32_t Engine::VoiceManagerResponder::initializeMultipleVoices(
                     v->attack();
                 }
                 voiceInitWorkingBuffer[idx] = v;
-                idx++;
             }
         }
         else
@@ -152,12 +152,11 @@ int32_t Engine::VoiceManagerResponder::initializeMultipleVoices(
                     v->attack();
                 }
                 voiceInitWorkingBuffer[idx] = v;
-                idx++;
             }
         }
     }
     engine.midiNoteStateCounter++;
-    return idx;
+    return nts;
 }
 
 void Engine::VoiceManagerResponder::releaseVoice(voice::Voice *v, float velocity) { v->release(); }