From 614953a222a427ff93dd7086b70ac4ddee641386 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Fri, 2 Jul 2021 22:36:35 -0400
Subject: [PATCH] Allows the low-pass filter to react to high-pass effects.

---
 Machines/Enterprise/Dave.cpp | 20 +++++++++-----------
 Machines/Enterprise/Dave.hpp |  2 +-
 2 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/Machines/Enterprise/Dave.cpp b/Machines/Enterprise/Dave.cpp
index 4f8f74ec8..474ee2940 100644
--- a/Machines/Enterprise/Dave.cpp
+++ b/Machines/Enterprise/Dave.cpp
@@ -124,6 +124,8 @@ void Audio::get_samples(std::size_t number_of_samples, int16_t *target) {
 		}
 
 		// Step 2: tick if necessary.
+		int noise_output = noise_.output & 1;
+		noise_.output <<= 1;
 		if(noise_tick) {
 			switch(noise_.polynomial) {
 				case Noise::Polynomial::SeventeenBit:
@@ -140,20 +142,16 @@ void Audio::get_samples(std::size_t number_of_samples, int16_t *target) {
 				break;
 			}
 
-			noise_.output <<= 1;
-			noise_.output |= poly_state_[int(Channel::Distortion::None)];
+			noise_output = poly_state_[int(Channel::Distortion::None)];
+		}
+		noise_.output |= noise_output;
 
-			// Low pass: sample channel 2 on downward transitions of the prima facie output.
-			if(noise_.low_pass) {
-				if((noise_.output & 3) == 2) {
-					noise_.output = (noise_.output & ~1) | (channels_[2].output & 1);
-				} else {
-					noise_.output = (noise_.output & ~1) | (noise_.output & 1);
-				}
-			}
+		// Low pass: sample channel 2 on downward transitions of the prima facie output.
+		if(noise_.low_pass && (noise_.output & 3) == 2) {
+			noise_.output = (noise_.output & ~1) | (channels_[2].output & 1);
 		}
 
-		// Apply noise high-pass at the rate of the tone channels.
+		// Apply noise high-pass.
 		if(noise_.high_pass && (channels_[0].output & 3) == 2) {
 			noise_.output &= ~1;
 		}
diff --git a/Machines/Enterprise/Dave.hpp b/Machines/Enterprise/Dave.hpp
index a280665af..fa867ccab 100644
--- a/Machines/Enterprise/Dave.hpp
+++ b/Machines/Enterprise/Dave.hpp
@@ -86,7 +86,7 @@ class Audio: public Outputs::Speaker::SampleSource {
 
 			// Current state.
 			int count = 0;
-			int output = false;
+			int output = 0;
 			bool final_output = false;
 		} noise_;
 		void update_noise();