From 5d638db094e6677240fb4766f2168c7b0791b677 Mon Sep 17 00:00:00 2001
From: notaz <notasas@gmail.com>
Date: Sat, 30 Sep 2017 22:55:57 +0300
Subject: [PATCH] handle frequent psg updates

---
 pico/memory.c      | 38 +++++++++++++++++++++++++++-----------
 pico/pico_cmn.c    |  2 ++
 pico/pico_int.h    |  3 ++-
 pico/sound/sound.c | 44 +++++++++++++++++++++++++++++++++++---------
 4 files changed, 66 insertions(+), 21 deletions(-)

diff --git a/pico/memory.c b/pico/memory.c
index fb5fa9be..0907696a 100644
--- a/pico/memory.c
+++ b/pico/memory.c
@@ -385,6 +385,28 @@ void NOINLINE ctl_write_z80reset(u32 d)
   }
 }
 
+static int get_scanline(int is_from_z80);
+
+static void psg_write_68k(u32 d)
+{
+  // look for volume write and update if needed
+  if ((d & 0x90) == 0x90 && PsndPsgLine < Pico.m.scanline)
+    PsndDoPSG(Pico.m.scanline);
+
+  SN76496Write(d);
+}
+
+static void psg_write_z80(u32 d)
+{
+  if ((d & 0x90) == 0x90) {
+    int scanline = get_scanline(1);
+    if (PsndPsgLine < scanline)
+      PsndDoPSG(scanline);
+  }
+
+  SN76496Write(d);
+}
+
 // -----------------------------------------------------------------
 
 #ifndef _ASM_MEMORY_C
@@ -528,8 +550,7 @@ static void PicoWrite8_z80(u32 a, u32 d)
   }
   // TODO: probably other VDP access too? Maybe more mirrors?
   if ((a & 0x7ff9) == 0x7f11) { // PSG Sound
-    if (PicoOpt & POPT_EN_PSG)
-      SN76496Write(d);
+    psg_write_68k(d);
     return;
   }
   if ((a & 0x7f00) == 0x6000) // Z80 BANK register
@@ -703,8 +724,7 @@ static u32 PicoRead16_vdp(u32 a)
 static void PicoWrite8_vdp(u32 a, u32 d)
 {
   if ((a & 0x00f9) == 0x0011) { // PSG Sound
-    if (PicoOpt & POPT_EN_PSG)
-      SN76496Write(d);
+    psg_write_68k(d);
     return;
   }
   if ((a & 0x00e0) == 0x0000) {
@@ -718,11 +738,8 @@ static void PicoWrite8_vdp(u32 a, u32 d)
 
 static void PicoWrite16_vdp(u32 a, u32 d)
 {
-  if ((a & 0x00f9) == 0x0010) { // PSG Sound
-    if (PicoOpt & POPT_EN_PSG)
-      SN76496Write(d);
-    return;
-  }
+  if ((a & 0x00f9) == 0x0010) // PSG Sound
+    psg_write_68k(d);
   if ((a & 0x00e0) == 0x0000) {
     PicoVideoWrite(a, d);
     return;
@@ -1198,8 +1215,7 @@ static void z80_md_vdp_br_write(unsigned int a, unsigned char data)
 {
   if ((a&0xfff9) == 0x7f11) // 7f11 7f13 7f15 7f17
   {
-    if (PicoOpt & POPT_EN_PSG)
-      SN76496Write(data);
+    psg_write_z80(data);
     return;
   }
   // at least VDP data writes hang my machine
diff --git a/pico/pico_cmn.c b/pico/pico_cmn.c
index b39cfdb2..78fdd120 100644
--- a/pico/pico_cmn.c
+++ b/pico/pico_cmn.c
@@ -264,6 +264,8 @@ static int PicoFrameHints(void)
     PicoSyncZ80(cycles);
   if (PsndOut && ym2612.dacen && PsndDacLine < lines)
     PsndDoDAC(lines - 1);
+  if (PsndOut && PsndPsgLine < lines)
+    PsndDoPSG(lines - 1);
 
 #ifdef PICO_CD
   if (PicoAHW & PAHW_MCD)
diff --git a/pico/pico_int.h b/pico/pico_int.h
index 551dcbc7..12769315 100644
--- a/pico/pico_int.h
+++ b/pico/pico_int.h
@@ -822,10 +822,11 @@ PICO_INTERNAL_ASM void wram_1M_to_2M(unsigned char *m);
 PICO_INTERNAL void PsndReset(void);
 PICO_INTERNAL void PsndStartFrame(void);
 PICO_INTERNAL void PsndDoDAC(int line_to);
+PICO_INTERNAL void PsndDoPSG(int line_to);
 PICO_INTERNAL void PsndClear(void);
 PICO_INTERNAL void PsndGetSamples(int y);
 PICO_INTERNAL void PsndGetSamplesMS(void);
-extern int PsndDacLine;
+extern int PsndDacLine, PsndPsgLine;
 
 // sms.c
 #ifndef NO_SMS
diff --git a/pico/sound/sound.c b/pico/sound/sound.c
index 8f88dd7c..510a9aba 100644
--- a/pico/sound/sound.c
+++ b/pico/sound/sound.c
@@ -19,7 +19,7 @@ void (*PsndMix_32_to_16l)(short *dest, int *src, int count) = mix_32_to_16l_ster
 // master int buffer to mix to
 static int PsndBuffer[2*(44100+100)/50];
 
-// dac
+// dac, psg
 static unsigned short dac_info[312+4]; // pos in sample buffer
 
 // cdda output buffer
@@ -30,7 +30,7 @@ int PsndRate=0;
 int PsndLen=0; // number of mono samples, multiply by 2 for stereo
 int PsndLen_exc_add=0; // this is for non-integer sample counts per line, eg. 22050/60
 int PsndLen_exc_cnt=0;
-int PsndDacLine=0;
+int PsndDacLine, PsndPsgLine;
 short *PsndOut=NULL; // PCM data buffer
 static int PsndLen_use;
 
@@ -158,7 +158,7 @@ PICO_INTERNAL void PsndStartFrame(void)
     PsndLen_use++;
   }
 
-  PsndDacLine = 0;
+  PsndDacLine = PsndPsgLine = 0;
   emustatus &= ~1;
   dac_info[224] = PsndLen_use;
 }
@@ -185,13 +185,42 @@ PICO_INTERNAL void PsndDoDAC(int line_to)
 
   if (PicoOpt & POPT_EN_STEREO) {
     short *d = PsndOut + pos*2;
-    for (; len > 0; len--, d+=2) *d = dout;
+    for (; len > 0; len--, d+=2) *d += dout;
   } else {
     short *d = PsndOut + pos;
-    for (; len > 0; len--, d++)  *d = dout;
+    for (; len > 0; len--, d++)  *d += dout;
   }
 }
 
+PICO_INTERNAL void PsndDoPSG(int line_to)
+{
+  int line_from = PsndPsgLine;
+  int pos, pos1, len;
+  int stereo = 0;
+
+  if (line_to >= 312)
+    line_to = 311;
+
+  pos  = dac_info[line_from];
+  pos1 = dac_info[line_to + 1];
+  len = pos1 - pos;
+  //elprintf(EL_STATUS, "%3d %3d %3d %3d %3d",
+  //  pos, pos1, len, line_from, line_to);
+  if (len <= 0)
+    return;
+
+  PsndPsgLine = line_to + 1;
+
+  if (!PsndOut || !(PicoOpt & POPT_EN_PSG))
+    return;
+
+  if (PicoOpt & POPT_EN_STEREO) {
+    stereo = 1;
+    pos <<= 1;
+  }
+  SN76496Update(PsndOut + pos, len, stereo);
+}
+
 // cdda
 static void cdda_raw_update(int *buffer, int length)
 {
@@ -264,10 +293,6 @@ static int PsndRender(int offset, int length)
 
   pprof_start(sound);
 
-  // PSG
-  if (PicoOpt & POPT_EN_PSG)
-    SN76496Update(PsndOut+offset, length, stereo);
-
   if (PicoAHW & PAHW_PICO) {
     PicoPicoPCMUpdate(PsndOut+offset, length, stereo);
     return length;
@@ -319,6 +344,7 @@ PICO_INTERNAL void PsndGetSamples(int y)
 
   if (ym2612.dacen && PsndDacLine < y)
     PsndDoDAC(y - 1);
+  PsndDoPSG(y - 1);
 
   if (y == 224)
   {
-- 
2.39.5