From 3bd9f6ff1aa5eec78a762c24c95cdddbefc5d70a Mon Sep 17 00:00:00 2001
From: dinkc64 <terra79pin@yahoo.com>
Date: Fri, 16 Aug 2024 20:55:49 -0400
Subject: [PATCH] nes_apu, dmc mode for arcade

---
 src/burn/snd/nes_apu.cpp | 8 ++++++++
 src/burn/snd/nes_apu.h   | 1 +
 2 files changed, 9 insertions(+)

diff --git a/src/burn/snd/nes_apu.cpp b/src/burn/snd/nes_apu.cpp
index 7962058112..5fe0ef8c80 100644
--- a/src/burn/snd/nes_apu.cpp
+++ b/src/burn/snd/nes_apu.cpp
@@ -105,11 +105,17 @@ struct nesapu_info
 static nesapu_info nesapu_chips[CHIP_NUM];
 
 static INT32 cycles_per_frame;
+static UINT32 arcade_mode = 0; // not cycle accurate dpcm/dmc (needed for arcade)
 
 #if 0
 INT32 nes_scanline();
 #endif
 
+void nesapuSetArcade(INT32 mode)
+{
+	arcade_mode = mode;
+}
+
 static UINT32 nes_nesapu_sync(INT32 samples_rate)
 {
 	return (samples_rate * M6502TotalCycles()) / cycles_per_frame; /* ntsc: (341*262 / 3) + 0.5 pal: (341*312 / 3.2) + 0.5*/
@@ -848,6 +854,8 @@ static void apu_update(struct nesapu_info *info)
 		INT32 dmc = dmc_buffer[dmcoffs];
 		INT32 ext = nes_ext_buffer[dmcoffs];
 
+		if (arcade_mode) dmc = apu_dpcm(info, &info->APU.dpcm);
+
 		INT32 out = (INT32)(((float)info->tnd_table[3*triangle + 2*noise + dmc] +
 							  info->square_table[square1 + square2] + info->square_table[square3 + square4]) * 0x3fff);
 
diff --git a/src/burn/snd/nes_apu.h b/src/burn/snd/nes_apu.h
index 9413cfb731..9bbadd8894 100644
--- a/src/burn/snd/nes_apu.h
+++ b/src/burn/snd/nes_apu.h
@@ -5,6 +5,7 @@ extern INT32 nesapu_mixermode;
 void nesapuInitPal(INT32 chip, INT32 clock, INT32 bAdd); // pal nes
 void nesapuInit(INT32 chip, INT32 clock, INT32 bAdd); // ntsc nes
 void nesapuInit(INT32 chip, INT32 clock, INT32 is_pal, UINT32 (*pSyncCallback)(INT32 samples_per_frame), INT32 nAdd);
+void nesapuSetArcade(INT32 mode);
 void nesapuUpdate(INT32 chip, INT16 *buffer, INT32 samples);
 void nesapuSetRoute(INT32 chip, INT32 nIndex, double nVolume, INT32 nRouteDir);
 void nesapuSetDMCBitDirection(INT32 reversed);