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https://github.com/libretro/MesenCE.git
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Sour
929d4dcc20
-Super Mario Land 2 - Pops in menu are fixed by immediately updating APU output after a write -Perfect Dark - Low voice volume is fixed by having the correct output when the channels are disabled (but DAC is still enabled) -Daiku no Gen - Low voice volume is fixed by keeping square channel output to digital 0 (= analog 1) until its first tick after being enabled (the game does not let the channel tick at all while the voice sample is playing)
88 lines
2.5 KiB
C++
88 lines
2.5 KiB
C++
#pragma once
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#include "pch.h"
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class GbEnvelope
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{
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public:
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template<typename T, typename U>
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static void ClockEnvelope(T& state, U& channel)
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{
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uint8_t timer = state.EnvTimer;
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if(state.EnvTimer == 0 || --state.EnvTimer == 0) {
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if(state.EnvPeriod > 0 && !state.EnvStopped) {
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if(state.EnvRaiseVolume && state.Volume < 0x0F) {
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state.Volume++;
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} else if(!state.EnvRaiseVolume && state.Volume > 0) {
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state.Volume--;
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} else {
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state.EnvStopped = true;
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}
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//Clocking envelope should update output immediately (based on div_trigger_volume/channel_4_volume_div tests)
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channel.UpdateOutput();
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state.EnvTimer = state.EnvPeriod;
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if(timer == 0) {
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//When the timer was already 0 (because period was 0), it looks like the next
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//clock occurs earlier than expected.
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//This fixes the last test result in channel_1_nrx2_glitch (but may be incorrect)
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state.EnvTimer--;
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}
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}
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}
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}
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template<typename T, typename U>
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static void WriteRegister(T& state, uint8_t value, U& channel)
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{
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bool raiseVolume = (value & 0x08) != 0;
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uint8_t period = value & 0x07;
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if((value & 0xF8) == 0) {
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state.Enabled = false;
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state.Output = 0;
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} else {
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//This implementation of the Zombie mode behavior differs from the description
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//found here: https://gbdev.gg8.se/wiki/articles/Gameboy_sound_hardware
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//Instead, it's based on the behavior of the channel_1_nrx2_glitch test and
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//and SameBoy's implementation of the glitch
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bool preventIncrement = false;
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if(raiseVolume != state.EnvRaiseVolume) {
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if(raiseVolume) {
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if(!state.EnvStopped && state.EnvPeriod == 0) {
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state.Volume ^= 0x0F;
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} else {
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state.Volume = 14 - state.Volume;
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}
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preventIncrement = true;
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} else {
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//"If the mode was changed (add to subtract or subtract to add), volume is set to 16 - volume."
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state.Volume = 16 - state.Volume;
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}
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//"Only the low 4 bits of volume are kept"
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state.Volume &= 0xF;
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}
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if(!state.EnvStopped && !preventIncrement) {
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if(state.EnvPeriod == 0 && (period || raiseVolume)) {
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if(raiseVolume) {
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//"If the old envelope period was zero and the envelope is still doing automatic updates, volume is incremented by 1"
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state.Volume++;
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} else {
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state.Volume--;
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}
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//"Only the low 4 bits of volume are kept"
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state.Volume &= 0xF;
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}
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}
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}
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state.EnvPeriod = period;
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state.EnvRaiseVolume = raiseVolume;
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state.EnvVolume = (value & 0xF0) >> 4;
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channel.UpdateOutput();
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}
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}; |