noise reset enable

CHANGES.md

@@ -3,6 +3,7 @@
 ### Version 0.2.2
 
 - Added SN76489 stereo separation to mixer menu
+- Added `NE0` / `NE1` noise reset enable effect
 - SN76489 VGM logger now eliminates extra register writes that have no side effects
 - Extended VGM header size so that it will not be misinterpreted by certain players
 - Fixed text export and import (for SN7T only)

NOTES.md

@@ -26,13 +26,29 @@ _(TODO)_
 
 - **Name:** Panning setting
 - **Target:** SN76489, ~~T6W28~~
-- **Description:** Changes the volume balance for the left and right output channels. `N01` is left, `N10` is center, `N1F` is right. ~~Intermediate values are supported only by the T6W28 chip; it effectively decreases the output volume in one of the output channels, but never silences it unless `N01` or `N1F` is used.~~ The special `N00` silences both output channels.
+- **Default:** `N10`
+- **Description:** Changes the volume balance for the left and right output channels. `N01` is left, `N10` is center, `N1F` is right. The special `N00` silences both output channels. ~~Intermediate values are supported only by the T6W28 chip; it effectively decreases the output volume in one of the output channels, but never silences it unless `N01` or `N1F` is used.~~
 
 #### NCx
 
 - **Name:** Channel swap
 - **Target:** SN76489
-- **Description:** Exchanges Square `x` with Square 3. This allows any square channel to control the pitch of the noise channel. Doing so will cause a pop in the audio output as it essentially tells the chip to swap two channels. Default is `NC3`, where no swapping occurs.
+- **Default:** `NC3`
+- **Description:** Exchanges Square `x` with Square 3. This allows any square channel to control the pitch of the noise channel. Doing so will cause a pop in the audio output as the channel registers must be rewritten.
+
+#### NE0, NE1
+
+- **Name:** Noise reset enable
+- **Target:** SN76489 Noise
+- **Default:** `NE0`
+- **Description:** Configures whether the noise channel resets its shift register state on new notes. `NE0` disables it, `NE1` enables it and additionally resets the noise state immediately. (Changing the pitch or duty always resets the noise state. This is normal SN76489 behaviour.)
+
+<!--
+- **Name:** a
+- **Target:** a
+- **Default:** ``
+- **Description:** a
+-->
 
 ## New features
 

Source/ChannelsSN7.cpp

@@ -249,6 +249,7 @@ void CNoiseChan::HandleNote(int Note, int Octave)
 		m_iPeriod = NesFreq;
 
 	m_bGate = true;
+	m_bTrigger = true;		// // //
 
 	m_iNote			= NewNote;
 	m_iDutyPeriod	= m_iDefaultDuty;
@@ -280,11 +281,26 @@ void CNoiseChan::RefreshChannel()
 	char NoiseMode = !(m_iDutyPeriod & 0x01);		// // //
 
 	int newCtrl = (NoiseMode << 2) | Period;		// // //
-	if (newCtrl != m_iLastCtrl) {
+	if ((m_bTrigger && m_bNoiseReset) || newCtrl != m_iLastCtrl) {
 		WriteRegister(0x06, newCtrl);
 		m_iLastCtrl = newCtrl;
 	}
 	WriteRegister(0x07, 0xF ^ Volume);
+
+	m_bTrigger = false;
+}
+
+void CNoiseChan::HandleCustomEffects(int EffNum, int EffParam)
+{
+	switch (EffNum) {
+	case EF_SN_CONTROL:
+		switch (EffParam) {
+		case 0xE0: m_bNoiseReset = false; return;
+		case 0xE1: m_bNoiseReset = m_bTrigger = true; return;
+		}
+	}
+
+	return CChannelHandlerSN7::HandleCustomEffects(EffNum, EffParam);
 }
 
 void CNoiseChan::ClearRegisters()
@@ -293,6 +309,7 @@ void CNoiseChan::ClearRegisters()
 	WriteRegister(0x06, 0);
 	WriteRegister(0x07, 0xF);
 	SetStereo(true, true);
+	m_bNoiseReset = false;
 }
 
 int CNoiseChan::TriggerNote(int Note)

Source/ChannelsSN7.h

@@ -73,6 +73,7 @@ class CNoiseChan : public CChannelHandlerSN7 {
 	CNoiseChan();
 	virtual void RefreshChannel();
 protected:
+	virtual void HandleCustomEffects(int EffNum, int EffParam);
 	virtual void ClearRegisters();
 	virtual void HandleNote(int Note, int Octave);
 	virtual void SetupSlide(int Type, int EffParam);
@@ -81,6 +82,8 @@ class CNoiseChan : public CChannelHandlerSN7 {
 
 private:
 	int m_iLastCtrl;		// // //
+	bool m_bNoiseReset;		// // //
+	bool m_bTrigger;		// // // 0CC-FT has this built-in
 };
 
 // // //