From df717ca9bf196fd40134d16f94b7f3c774f2c897 Mon Sep 17 00:00:00 2001
From: notaz <notasas@gmail.com>
Date: Mon, 5 Sep 2022 19:41:52 +0300
Subject: [PATCH] cdrom: try to eliminate playback timing drifting

---
 libpcsxcore/cdrom.c  | 28 ++++++++++++++++------------
 libpcsxcore/r3000a.h | 14 ++++++++------
 2 files changed, 24 insertions(+), 18 deletions(-)

diff --git a/libpcsxcore/cdrom.c b/libpcsxcore/cdrom.c
index fb526b40..184d07ab 100644
--- a/libpcsxcore/cdrom.c
+++ b/libpcsxcore/cdrom.c
@@ -242,11 +242,15 @@ static void sec2msf(unsigned int s, u8 *msf) {
 }
 
 // cdrPlaySeekReadInterrupt
-#define CDRPLAYSEEKREAD_INT(eCycle) { \
+#define CDRPLAYSEEKREAD_INT(eCycle, isFirst) { \
+	u32 e_ = eCycle; \
 	psxRegs.interrupt |= (1 << PSXINT_CDREAD); \
-	psxRegs.intCycle[PSXINT_CDREAD].cycle = eCycle; \
-	psxRegs.intCycle[PSXINT_CDREAD].sCycle = psxRegs.cycle; \
-	new_dyna_set_event(PSXINT_CDREAD, eCycle); \
+	if (isFirst) \
+		psxRegs.intCycle[PSXINT_CDREAD].sCycle = psxRegs.cycle; \
+	else \
+		psxRegs.intCycle[PSXINT_CDREAD].sCycle += psxRegs.intCycle[PSXINT_CDREAD].cycle; \
+	psxRegs.intCycle[PSXINT_CDREAD].cycle = e_; \
+	new_dyna_set_event_abs(PSXINT_CDREAD, psxRegs.intCycle[PSXINT_CDREAD].sCycle + e_); \
 }
 
 // cdrLidSeekInterrupt
@@ -588,7 +592,7 @@ void cdrPlaySeekReadInterrupt(void)
 	if (!cdr.Play && (cdr.StatP & STATUS_SEEK)) {
 		if (cdr.Stat) {
 			CDR_LOG_I("cdrom: seek stat hack\n");
-			CDRPLAYSEEKREAD_INT(0x1000);
+			CDRPLAYSEEKREAD_INT(0x1000, 1);
 			return;
 		}
 		SetResultSize(1);
@@ -640,7 +644,7 @@ void cdrPlaySeekReadInterrupt(void)
 		}
 	}
 
-	CDRPLAYSEEKREAD_INT(cdReadTime);
+	CDRPLAYSEEKREAD_INT(cdReadTime, 0);
 
 	// update for CdlGetlocP/autopause
 	generate_subq(cdr.SetSectorPlay);
@@ -766,7 +770,7 @@ void cdrInterrupt(void) {
 			// BIOS player - set flag again
 			cdr.Play = TRUE;
 
-			CDRPLAYSEEKREAD_INT(cdReadTime + seekTime);
+			CDRPLAYSEEKREAD_INT(cdReadTime + seekTime, 1);
 			start_rotating = 1;
 			break;
 
@@ -974,7 +978,7 @@ void cdrInterrupt(void) {
 			Rockman X5 = 0.5-4x
 			- fix capcom logo
 			*/
-			CDRPLAYSEEKREAD_INT(cdReadTime + seekTime);
+			CDRPLAYSEEKREAD_INT(cdReadTime + seekTime, 1);
 			start_rotating = 1;
 			break;
 
@@ -1072,7 +1076,7 @@ void cdrInterrupt(void) {
 			// - fixes new game
 			ReadTrack(cdr.SetSectorPlay);
 
-			CDRPLAYSEEKREAD_INT(((cdr.Mode & 0x80) ? (cdReadTime) : cdReadTime * 2) + seekTime);
+			CDRPLAYSEEKREAD_INT(((cdr.Mode & 0x80) ? (cdReadTime) : cdReadTime * 2) + seekTime, 1);
 
 			SetPlaySeekRead(cdr.StatP, STATUS_SEEK);
 			start_rotating = 1;
@@ -1168,7 +1172,7 @@ static void cdrReadInterrupt(void)
 
 	if (cdr.Irq || cdr.Stat) {
 		CDR_LOG_I("cdrom: read stat hack %02x %x\n", cdr.Irq, cdr.Stat);
-		CDRPLAYSEEKREAD_INT(2048);
+		CDRPLAYSEEKREAD_INT(2048, 1);
 		return;
 	}
 
@@ -1235,7 +1239,7 @@ static void cdrReadInterrupt(void)
 
 	cdr.Readed = 0;
 
-	CDRPLAYSEEKREAD_INT((cdr.Mode & MODE_SPEED) ? (cdReadTime / 2) : cdReadTime);
+	CDRPLAYSEEKREAD_INT((cdr.Mode & MODE_SPEED) ? (cdReadTime / 2) : cdReadTime, 0);
 
 	/*
 	Croc 2: $40 - only FORM1 (*)
@@ -1588,7 +1592,7 @@ int cdrFreeze(void *f, int Mode) {
 			if (!Config.Cdda)
 				CDR_play(cdr.SetSectorPlay);
 			if (psxRegs.interrupt & (1 << PSXINT_CDRPLAY_OLD))
-				CDRPLAYSEEKREAD_INT((cdr.Mode & 0x80) ? (cdReadTime / 2) : cdReadTime);
+				CDRPLAYSEEKREAD_INT((cdr.Mode & 0x80) ? (cdReadTime / 2) : cdReadTime, 1);
 		}
 
 		if ((cdr.freeze_ver & 0xffffff00) != 0x63647200) {
diff --git a/libpcsxcore/r3000a.h b/libpcsxcore/r3000a.h
index ea6f0e75..49afcb1c 100644
--- a/libpcsxcore/r3000a.h
+++ b/libpcsxcore/r3000a.h
@@ -206,17 +206,19 @@ void new_dyna_before_save(void);
 void new_dyna_after_save(void);
 void new_dyna_freeze(void *f, int mode);
 
-#define new_dyna_set_event(e, c) { \
-	s32 c_ = c; \
-	u32 abs_ = psxRegs.cycle + c_; \
-	s32 odi_ = next_interupt - psxRegs.cycle; \
+#define new_dyna_set_event_abs(e, abs) { \
+	u32 abs_ = abs; \
+	s32 di_ = next_interupt - abs_; \
 	event_cycles[e] = abs_; \
-	if (c_ < odi_) { \
-		/*printf("%u: next_interupt %d -> %d (%u)\n", psxRegs.cycle, odi_, c_, abs_);*/ \
+	if (di_ > 0) { \
+		/*printf("%u: next_interupt %u -> %u\n", psxRegs.cycle, next_interupt, abs_);*/ \
 		next_interupt = abs_; \
 	} \
 }
 
+#define new_dyna_set_event(e, c) \
+	new_dyna_set_event_abs(e, psxRegs.cycle + (c))
+
 #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 
 #define _i32(x) *(s32 *)&x
-- 
2.39.5