From e12dc5d89445c9c6ae4d9d5d5bd7151fc899d539 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Wed, 6 May 2020 00:15:28 -0400
Subject: [PATCH] Reduce the amount of time spent installing instruments.

---
 Components/OPL2/OPLL.cpp | 14 +++++++++++---
 Components/OPL2/OPLL.hpp |  2 +-
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/Components/OPL2/OPLL.cpp b/Components/OPL2/OPLL.cpp
index f2e1dcf13..737284c44 100644
--- a/Components/OPL2/OPLL.cpp
+++ b/Components/OPL2/OPLL.cpp
@@ -27,6 +27,11 @@ OPLL::OPLL(Concurrency::DeferringAsyncTaskQueue &task_queue, int audio_divider,
 			phase_generators_[c + 9].reset();
 		});
 	}
+
+	// Set default instrument.
+	for(int c = 0; c < 9; ++c) {
+		install_instrument(c);
+	}
 }
 
 // MARK: - Machine-facing programmatic input.
@@ -112,11 +117,14 @@ void OPLL::write_register(uint8_t address, uint8_t value) {
 			// instead nominate additional attenuations. This code reads those back
 			// from the stored instrument values.
 			case 0x30:
-				channels_[index].instrument = value >> 4;
 				channels_[index].attenuation = value & 0xf;
 
-				if(index < 6 || !rhythm_mode_enabled_) {
-					install_instrument(index);
+				// Install an instrument only if it's new.
+				if(channels_[index].instrument != value >> 4) {
+					channels_[index].instrument = value >> 4;
+					if(index < 6 || !rhythm_mode_enabled_) {
+						install_instrument(index);
+					}
 				}
 			return;
 		}
diff --git a/Components/OPL2/OPLL.hpp b/Components/OPL2/OPLL.hpp
index 7d7b409de..91beabc2e 100644
--- a/Components/OPL2/OPLL.hpp
+++ b/Components/OPL2/OPLL.hpp
@@ -83,7 +83,7 @@ class OPLL: public OPLBase<OPLL> {
 		bool is_vrc7_ = false;
 
 		// Contains the current configuration of the custom instrument.
-		uint8_t custom_instrument_[8];
+		uint8_t custom_instrument_[8] = {0, 0, 0, 0, 0, 0, 0, 0};
 
 		// Helpers to push per-channel information.