From 07c2b3aa055936a3ec4fc93dd25309609e1bca4c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Antonio=20Ni=C3=B1o=20D=C3=ADaz?= <antonio_nd@outlook.com>
Date: Tue, 30 Mar 2021 22:06:28 +0100
Subject: [PATCH] Fix PSG channel 3 one-shot mode

---
 source/gb_core/sound.c  | 38 ++++++++++++++++++----------------
 source/gba_core/sound.c | 45 ++++++++++++++++++++---------------------
 2 files changed, 43 insertions(+), 40 deletions(-)

diff --git a/source/gb_core/sound.c b/source/gb_core/sound.c
index fb21f42..f5a2f97 100644
--- a/source/gb_core/sound.c
+++ b/source/gb_core/sound.c
@@ -543,7 +543,7 @@ void GB_SoundRegWrite(u32 address, u32 value)
             Sound.Chn1.frequency = freq;
             Sound.Chn1.frequency_steps = freq;
 
-            Sound.Chn1.limittime = (Sound.Chn1.reg[4] & (1 << 6));
+            Sound.Chn1.limittime = (value & (1 << 6));
 
             if (value & (1 << 7))
             {
@@ -712,16 +712,17 @@ void GB_SoundRegWrite(u32 address, u32 value)
 
             Sound.Chn3.limittime = (value & (1 << 6));
 
-            if (Sound.Chn3.playing) // ?
+            if (Sound.Chn3.playing && (value & (1 << 7)))
             {
-                if (value & (1 << 7))
-                {
-                    //Sound.Chn3.playing = 1; // ?
-                    Sound.Chn3.samplecount = 0;
-                    mem->IO_Ports[NR52_REG - 0xFF00] |= (1 << 2);
-                    GB_SoundLoadWave();
-                    Sound.Chn3.running = 1;
-                }
+                Sound.Chn3.samplecount = 0;
+                mem->IO_Ports[NR52_REG - 0xFF00] |= (1 << 2);
+                GB_SoundLoadWave();
+                Sound.Chn3.running = 1;
+            }
+            else
+            {
+                Sound.Chn3.running = 0;
+                mem->IO_Ports[NR52_REG - 0xFF00] &= ~(1 << 2);
             }
             return;
         }
@@ -1107,14 +1108,17 @@ void GB_SoundUpdateClocksCounterReference(int reference_clocks)
             // Channel 3
             if (Sound.Chn3.running)
             {
-                if (Sound.Chn3.stepsleft > 0)
-                {
-                    Sound.Chn3.stepsleft--;
-                }
-                else if (Sound.Chn3.limittime)
+                if (Sound.Chn3.limittime)
                 {
-                    Sound.Chn3.running = 0;
-                    mem->IO_Ports[NR52_REG - 0xFF00] &= ~(1 << 2);
+                    if (Sound.Chn3.stepsleft > 0)
+                    {
+                        Sound.Chn3.stepsleft--;
+                    }
+                    else
+                    {
+                        Sound.Chn3.running = 0;
+                        mem->IO_Ports[NR52_REG - 0xFF00] &= ~(1 << 2);
+                    }
                 }
             }
 
diff --git a/source/gba_core/sound.c b/source/gba_core/sound.c
index 11502fc..75d3848 100644
--- a/source/gba_core/sound.c
+++ b/source/gba_core/sound.c
@@ -752,14 +752,17 @@ u32 GBA_SoundUpdate(u32 clocks)
             // Channel 3
             if (Sound.Chn3.running)
             {
-                if (Sound.Chn3.stepsleft > 0)
+                if (Sound.Chn3.limittime)
                 {
-                    Sound.Chn3.stepsleft--;
-                }
-                else if (Sound.Chn3.limittime)
-                {
-                    Sound.Chn3.running = 0;
-                    REG_SOUNDCNT_X &= ~(1 << 2);
+                    if (Sound.Chn3.stepsleft > 0)
+                    {
+                        Sound.Chn3.stepsleft--;
+                    }
+                    else
+                    {
+                        Sound.Chn3.running = 0;
+                        REG_SOUNDCNT_X &= ~(1 << 2);
+                    }
                 }
             }
 
@@ -1208,26 +1211,22 @@ void GBA_SoundRegWrite16(u32 address, u16 value)
         case SOUND3CNT_X:
             Sound.Chn3.reg[2] = value;
 
-            if (Sound.Chn3.playing)
-            {
-                Sound.Chn3.frequency = value & 0x07FF;
-                Sound.Chn3.frequency_steps = Sound.Chn3.frequency;
-            }
+            Sound.Chn3.frequency = value & 0x07FF;
+            Sound.Chn3.frequency_steps = Sound.Chn3.frequency;
 
-            Sound.Chn3.limittime = (value & (1 << 6));
+            Sound.Chn3.limittime = (value & (1 << 14));
 
-            if (Sound.Chn3.playing) // ?
+            if (Sound.Chn3.playing && (value & (1 << 15)))
             {
                 Sound.Chn3.samplecount = 0;
-
-                if (value & (1 << 15))
-                {
-                    //Sound.Chn3.playing = 1; // ?
-                    Sound.Chn3.samplecount = 0;
-                    REG_SOUNDCNT_X |= (1 << 2);
-                    GBA_SoundLoadWave();
-                    Sound.Chn3.running = 1;
-                }
+                REG_SOUNDCNT_X |= (1 << 2);
+                GBA_SoundLoadWave();
+                Sound.Chn3.running = 1;
+            }
+            else
+            {
+                Sound.Chn3.running = 0;
+                REG_SOUNDCNT_X &= ~(1 << 2);
             }
             return;