From 45a1ef7153910f005c01cba63d12f312071efef0 Mon Sep 17 00:00:00 2001
From: notaz <notasas@gmail.com>
Date: Thu, 26 Jun 2008 19:32:34 +0000
Subject: [PATCH] tried to adjust timers using formulae

git-svn-id: file:///home/notaz/opt/svn/PicoDrive@497 be3aeb3a-fb24-0410-a615-afba39da0efa
---
 Pico/Memory.c                  |  4 ++--
 Pico/PicoInt.h                 |  8 ++++++--
 platform/linux/940ctl_ym2612.c | 10 ++++++++++
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/Pico/Memory.c b/Pico/Memory.c
index 755b5b50..99f78460 100644
--- a/Pico/Memory.c
+++ b/Pico/Memory.c
@@ -798,7 +798,7 @@ int ym2612_write_local(u32 a, u32 d, int is_from_z80)
             ym2612.OPN.ST.TA = TAnew;
             //ym2612.OPN.ST.TAC = (1024-TAnew)*18;
             //ym2612.OPN.ST.TAT = 0;
-            timer_a_step = timer_a_offset = 16466 * (1024 - TAnew);
+            timer_a_step = timer_a_offset = TIMER_A_TICK_ZCYCLES * (1024 - TAnew);
             if (ym2612.OPN.ST.mode & 1) {
               int cycles = is_from_z80 ? z80_cyclesDone() : cycles_68k_to_z80(SekCyclesDone());
               timer_a_next_oflow = (cycles << 8) + timer_a_step;
@@ -813,7 +813,7 @@ int ym2612_write_local(u32 a, u32 d, int is_from_z80)
             ym2612.OPN.ST.TB = d;
             //ym2612.OPN.ST.TBC = (256-d) * 288;
             //ym2612.OPN.ST.TBT  = 0;
-            timer_b_step = timer_b_offset = 262800 * (256 - d); // 262881
+            timer_b_step = timer_b_offset = TIMER_B_TICK_ZCYCLES * (256 - d); // 262800
             if (ym2612.OPN.ST.mode & 2) {
               int cycles = is_from_z80 ? z80_cyclesDone() : cycles_68k_to_z80(SekCyclesDone());
               timer_b_next_oflow = (cycles << 8) + timer_b_step;
diff --git a/Pico/PicoInt.h b/Pico/PicoInt.h
index c2f8b60f..4ac115f3 100644
--- a/Pico/PicoInt.h
+++ b/Pico/PicoInt.h
@@ -480,6 +480,10 @@ void ym2612_pack_state(void);
 void ym2612_unpack_state(void);
 
 #define TIMER_NO_OFLOW 0x70000000
+// tA =   72 * (1024 - NA) / M
+#define TIMER_A_TICK_ZCYCLES  17203
+// tB = 1152 * (256 - NA) / M
+#define TIMER_B_TICK_ZCYCLES 262800 // 275251 broken, see Dai Makaimura
 
 #define timers_cycle() \
   if (timer_a_next_oflow > 0 && timer_a_next_oflow < TIMER_NO_OFLOW) \
@@ -490,8 +494,8 @@ void ym2612_unpack_state(void);
 
 #define timers_reset() \
   timer_a_next_oflow = timer_b_next_oflow = TIMER_NO_OFLOW; \
-  timer_a_step = timer_a_offset = 16495 * 1024; \
-  timer_b_step = timer_b_offset = 263912 * 256;
+  timer_a_step = timer_a_offset = TIMER_A_TICK_ZCYCLES * 1024; \
+  timer_b_step = timer_b_offset = TIMER_B_TICK_ZCYCLES * 256;
 
 
 // VideoPort.c
diff --git a/platform/linux/940ctl_ym2612.c b/platform/linux/940ctl_ym2612.c
index 32e672fd..b6b593ac 100644
--- a/platform/linux/940ctl_ym2612.c
+++ b/platform/linux/940ctl_ym2612.c
@@ -53,6 +53,16 @@ void YM2612PicoStateLoad_940(void)
 	}
 }
 
+void YM2612PicoStateSave2_940(int tat, int tbt)
+{
+	YM2612PicoStateSave2(tat, tbt);
+}
+
+int YM2612PicoStateLoad2_940(int *tat, int *tbt)
+{
+	return YM2612PicoStateLoad2(tat, tbt);
+}
+
 
 void sharedmem_init(void)
 {
-- 
2.39.5