From: kub <derkub@gmail.com>
Date: Sat, 22 Jun 2024 21:12:31 +0000 (+0200)
Subject: core, revisit ym2612 busy flag implementation
X-Git-Tag: v2.00~28
X-Git-Url: https://notaz.gp2x.de/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f5c022a8e4905a5fb8947f807d42eaeed6ad6f72;p=picodrive.git

core, revisit ym2612 busy flag implementation
---

diff --git a/pico/memory.c b/pico/memory.c
index de5e3e5e..b1c917a1 100644
--- a/pico/memory.c
+++ b/pico/memory.c
@@ -1174,7 +1174,7 @@ static int ym2612_write_local(u32 a, u32 d, int is_from_z80)
 
       // the busy flag in the YM2612 status is actually a 32 cycle timer
       // (89.6 Z80 cycles), triggered by any write to the data port.
-      Pico.t.ym2612_busy = (cycles + 90) << 8; // Q8 for convenience
+      Pico.t.ym2612_busy = (cycles << 8) + YMBUSY_ZCYCLES; // Q8 for convenience
 
       switch (addr)
       {
@@ -1284,9 +1284,11 @@ static u32 ym2612_read_local_68k(void)
 void ym2612_pack_state(void)
 {
   // timers are saved as tick counts, in 16.16 int format
-  int tac, tat = 0, tbc, tbt = 0;
+  int tac, tat = 0, tbc, tbt = 0, busy = 0;
   tac = 1024 - ym2612.OPN.ST.TA;
   tbc = 256  - ym2612.OPN.ST.TB;
+  if (Pico.t.ym2612_busy > 0)
+    busy = cycles_z80_to_68k(Pico.t.ym2612_busy);
   if (Pico.t.timer_a_next_oflow != TIMER_NO_OFLOW)
     tat = (int)((double)(Pico.t.timer_a_step - Pico.t.timer_a_next_oflow)
           / (double)Pico.t.timer_a_step * tac * 65536);
@@ -1301,12 +1303,12 @@ void ym2612_pack_state(void)
     YM2612PicoStateSave2_940(tat, tbt);
   else
 #endif
-    YM2612PicoStateSave2(tat, tbt);
+    YM2612PicoStateSave2(tat, tbt, busy);
 }
 
 void ym2612_unpack_state(void)
 {
-  int i, ret, tac, tat, tbc, tbt;
+  int i, ret, tac, tat, tbc, tbt, busy = 0;
   YM2612PicoStateLoad();
 
   // feed all the registers and update internal state
@@ -1336,12 +1338,13 @@ void ym2612_unpack_state(void)
     ret = YM2612PicoStateLoad2_940(&tat, &tbt);
   else
 #endif
-    ret = YM2612PicoStateLoad2(&tat, &tbt);
+    ret = YM2612PicoStateLoad2(&tat, &tbt, &busy);
   if (ret != 0) {
     elprintf(EL_STATUS, "old ym2612 state");
     return; // no saved timers
   }
 
+  Pico.t.ym2612_busy = cycles_68k_to_z80(busy);
   tac = (1024 - ym2612.OPN.ST.TA) << 16;
   tbc = (256  - ym2612.OPN.ST.TB) << 16;
   if (ym2612.OPN.ST.mode & 1)
diff --git a/pico/pico_int.h b/pico/pico_int.h
index 06f00c2f..79997d9b 100644
--- a/pico/pico_int.h
+++ b/pico/pico_int.h
@@ -209,6 +209,7 @@ extern struct DrZ80 drZ80;
 
 // 68k clock = OSC/7, z80 clock = OSC/15, 68k:z80 ratio = 7/15 = 3822.9/8192
 #define cycles_68k_to_z80(x) ((x) * 3823 >> 13)
+#define cycles_z80_to_68k(x) ((x) * 8777 >> 12)
 
 // ----------------------- SH2 CPU -----------------------
 
@@ -898,10 +899,12 @@ void ym2612_unpack_state(void);
 
 #define TIMER_NO_OFLOW 0x70000000
 
-// tA =    72 * (1024 - TA) / M, with M = mclock/2
-#define TIMER_A_TICK_ZCYCLES cycles_68k_to_z80(256LL*   72*2) // Q8
-// tB = 16*72 * ( 256 - TB) / M
-#define TIMER_B_TICK_ZCYCLES cycles_68k_to_z80(256LL*16*72*2) // Q8
+// tA =    24*3 * (1024 - TA) / M, with M = mclock/2
+#define TIMER_A_TICK_ZCYCLES cycles_68k_to_z80(256LL*   24*3*2) // Q8
+// tB = 16*24*3 * ( 256 - TB) / M
+#define TIMER_B_TICK_ZCYCLES cycles_68k_to_z80(256LL*16*24*3*2) // Q8
+// busy =  32*3 / M
+#define YMBUSY_ZCYCLES       cycles_68k_to_z80(256LL*   32*3*2) // Q8
 
 #define timers_cycle(ticks) \
   if (Pico.t.ym2612_busy > 0) \
diff --git a/pico/sound/ym2612.c b/pico/sound/ym2612.c
index f0e60b42..ee84da23 100644
--- a/pico/sound/ym2612.c
+++ b/pico/sound/ym2612.c
@@ -2049,7 +2049,7 @@ typedef struct
 	UINT32  eg_timer;
 	UINT32  lfo_cnt;
 	UINT16  lfo_ampm;
-	UINT16  unused2;
+	INT16   busy_timer;
 	UINT32  keyon_field;	// 20
 	UINT32  kcode_fc_sl3_3;
 	UINT32  reserved[2];
@@ -2063,7 +2063,7 @@ typedef struct
 } ym_save_addon2;
 
 
-void YM2612PicoStateSave2(int tat, int tbt)
+void YM2612PicoStateSave2(int tat, int tbt, int busy)
 {
 	ym_save_addon_slot ss;
 	ym_save_addon2 sa2;
@@ -2121,10 +2121,11 @@ void YM2612PicoStateSave2(int tat, int tbt)
 	sa.eg_timer = ym2612.OPN.eg_timer;
 	sa.lfo_cnt  = ym2612.OPN.lfo_cnt;
 	sa.lfo_ampm = g_lfo_ampm;
+	sa.busy_timer = busy;
 	memcpy(ptr, &sa, sizeof(sa)); // 0x30 max
 }
 
-int YM2612PicoStateLoad2(int *tat, int *tbt)
+int YM2612PicoStateLoad2(int *tat, int *tbt, int *busy)
 {
 	ym_save_addon_slot ss;
 	ym_save_addon2 sa2;
@@ -2150,6 +2151,7 @@ int YM2612PicoStateLoad2(int *tat, int *tbt)
 	g_lfo_ampm = sa.lfo_ampm;
 	if (tat != NULL) *tat = sa.TAT;
 	if (tbt != NULL) *tbt = sa.TBT;
+	if (busy != NULL) *busy = sa.busy_timer;
 
 	// chans 1,2,3
 	ptr = &ym2612.REGS[0x0b8];
diff --git a/pico/sound/ym2612.h b/pico/sound/ym2612.h
index b981a428..56ec5ef9 100644
--- a/pico/sound/ym2612.h
+++ b/pico/sound/ym2612.h
@@ -177,8 +177,8 @@ int  YM2612PicoTick_(int n);
 void YM2612PicoStateLoad_(void);
 
 void *YM2612GetRegs(void);
-void YM2612PicoStateSave2(int tat, int tbt);
-int  YM2612PicoStateLoad2(int *tat, int *tbt);
+void YM2612PicoStateSave2(int tat, int tbt, int busy);
+int  YM2612PicoStateLoad2(int *tat, int *tbt, int *busy);
 
 /* NB must be macros for compiling GP2X 940 code */
 #ifndef __GP2X__
diff --git a/platform/gp2x/code940/940.c b/platform/gp2x/code940/940.c
index 4ab8bad1..60be15c3 100644
--- a/platform/gp2x/code940/940.c
+++ b/platform/gp2x/code940/940.c
@@ -187,7 +187,7 @@ void Main940(void)
 				break;
 
 			case JOB940_PICOSTATESAVE2:
-				YM2612PicoStateSave2(0, 0);
+				YM2612PicoStateSave2(0, 0, 0);
 				memcpy(shared_ctl->writebuff0, ym2612_940->REGS, 0x200);
 				break;
 
@@ -197,7 +197,7 @@ void Main940(void)
 
 			case JOB940_PICOSTATELOAD2:
 				memcpy(ym2612_940->REGS, shared_ctl->writebuff0, 0x200);
-				YM2612PicoStateLoad2(0, 0);
+				YM2612PicoStateLoad2(0, 0, 0);
 				break;
 
 			case JOB940_YM2612UPDATEONE: