From 3162a7104cbb9c1046a3d780dfc74bbc684bdc5b Mon Sep 17 00:00:00 2001
From: notaz <notasas@gmail.com>
Date: Wed, 4 Oct 2017 02:23:27 +0300
Subject: [PATCH] adjust z80 timing a bit

---
 pico/memory.c   | 18 +++++++++---------
 pico/pico.c     | 21 ++++++++-------------
 pico/pico_cmn.c |  3 ++-
 pico/pico_int.h | 23 +++++++++++++----------
 4 files changed, 32 insertions(+), 33 deletions(-)

diff --git a/pico/memory.c b/pico/memory.c
index 858ab65f..436f5453 100644
--- a/pico/memory.c
+++ b/pico/memory.c
@@ -331,11 +331,10 @@ NOINLINE void io_ports_write(u32 a, u32 d)
   Pico.ioports[a] = d;
 }
 
-// lame..
 static int z80_cycles_from_68k(void)
 {
-  return z80_cycle_aim
-    + cycles_68k_to_z80(SekCyclesDone() - last_z80_sync);
+  int m68k_cnt = SekCyclesDone() - timing.m68c_frame_start;
+  return cycles_68k_to_z80(m68k_cnt);
 }
 
 void NOINLINE ctl_write_z80busreq(u32 d)
@@ -346,7 +345,7 @@ void NOINLINE ctl_write_z80busreq(u32 d)
   {
     if (d)
     {
-      z80_cycle_cnt = z80_cycles_from_68k();
+      timing.z80c_cnt = z80_cycles_from_68k() + 2;
     }
     else
     {
@@ -378,7 +377,7 @@ void NOINLINE ctl_write_z80reset(u32 d)
     }
     else
     {
-      z80_cycle_cnt = z80_cycles_from_68k();
+      timing.z80c_cnt = z80_cycles_from_68k() + 2;
       z80_reset();
     }
     Pico.m.z80_reset = d;
@@ -896,10 +895,11 @@ static void m68k_mem_setup(void)
 static int get_scanline(int is_from_z80)
 {
   if (is_from_z80) {
-    int cycles = z80_cyclesDone();
-    while (cycles - z80_scanline_cycles >= 228)
-      z80_scanline++, z80_scanline_cycles += 228;
-    return z80_scanline;
+    int mclk_z80 = z80_cyclesDone() * 15;
+    int mclk_line = timing.z80_scanline * 488 * 7;
+    while (mclk_z80 - mclk_line >= 488 * 7)
+      timing.z80_scanline++, mclk_line += 488 * 7;
+    return timing.z80_scanline;
   }
 
   return Pico.m.scanline;
diff --git a/pico/pico.c b/pico/pico.c
index f0c54d17..0404367c 100644
--- a/pico/pico.c
+++ b/pico/pico.c
@@ -23,6 +23,8 @@ int PicoAutoRgnOrder;
 struct PicoSRAM SRam;
 int emustatus;         // rapid_ym2612, multi_ym_updates
 
+struct PicoTiming timing;
+
 void (*PicoWriteSound)(int len) = NULL; // called at the best time to send sound buffer (PsndOut) to hardware
 void (*PicoResetHook)(void) = NULL;
 void (*PicoLineHook)(void) = NULL;
@@ -278,31 +280,24 @@ PICO_INTERNAL int CheckDMA(void)
 
 #include "pico_cmn.c"
 
-unsigned int last_z80_sync; /* in 68k cycles */
-int z80_cycle_cnt;
-int z80_cycle_aim;
-int z80_scanline;
-int z80_scanline_cycles;  /* cycles done until z80_scanline */
-
 /* sync z80 to 68k */
 PICO_INTERNAL void PicoSyncZ80(unsigned int m68k_cycles_done)
 {
   int m68k_cnt;
   int cnt;
 
-  m68k_cnt = m68k_cycles_done - last_z80_sync;
-  z80_cycle_aim += cycles_68k_to_z80(m68k_cnt);
-  cnt = z80_cycle_aim - z80_cycle_cnt;
-  last_z80_sync = m68k_cycles_done;
+  m68k_cnt = m68k_cycles_done - timing.m68c_frame_start;
+  timing.z80c_aim = cycles_68k_to_z80(m68k_cnt);
+  cnt = timing.z80c_aim - timing.z80c_cnt;
 
   pprof_start(z80);
 
   elprintf(EL_BUSREQ, "z80 sync %i (%u|%u -> %u|%u)", cnt,
-    z80_cycle_cnt, z80_cycle_cnt / 228,
-    z80_cycle_aim, z80_cycle_aim / 228);
+    timing.z80c_cnt, timing.z80c_cnt * 15 / 7 / 488,
+    timing.z80c_aim, timing.z80c_aim * 15 / 7 / 488);
 
   if (cnt > 0)
-    z80_cycle_cnt += z80_run(cnt);
+    timing.z80c_cnt += z80_run(cnt);
 
   pprof_end(z80);
 }
diff --git a/pico/pico_cmn.c b/pico/pico_cmn.c
index b44bfba2..01d57a72 100644
--- a/pico/pico_cmn.c
+++ b/pico/pico_cmn.c
@@ -78,7 +78,6 @@ static int PicoFrameHints(void)
   int hint; // Hint counter
 
   pevt_log_m68k_o(EVT_FRAME_START);
-  pv->v_counter = Pico.m.scanline = 0;
 
   if ((PicoOpt&POPT_ALT_RENDERER) && !PicoSkipFrame && (pv->reg[1]&0x40)) { // fast rend., display enabled
     // draw a frame just after vblank in alternative render mode
@@ -91,6 +90,8 @@ static int PicoFrameHints(void)
   }
   else skip=PicoSkipFrame;
 
+  timing.m68c_frame_start = SekCyclesDone();
+  pv->v_counter = Pico.m.scanline = 0;
   z80_resetCycles();
   PsndStartFrame();
 
diff --git a/pico/pico_int.h b/pico/pico_int.h
index 743ecb48..89cccc79 100644
--- a/pico/pico_int.h
+++ b/pico/pico_int.h
@@ -211,20 +211,13 @@ extern struct DrZ80 drZ80;
 
 #define Z80_STATE_SIZE 0x60
 
-extern unsigned int last_z80_sync;
-extern int z80_cycle_cnt;        /* 'done' z80 cycles before z80_run() */
-extern int z80_cycle_aim;
-extern int z80_scanline;
-extern int z80_scanline_cycles;  /* cycles done until z80_scanline */
-
 #define z80_resetCycles() \
-  last_z80_sync = SekCyclesDone(); \
-  z80_cycle_cnt = z80_cycle_aim = z80_scanline = z80_scanline_cycles = 0;
+  timing.z80c_cnt = timing.z80c_aim = timing.z80_scanline = 0
 
 #define z80_cyclesDone() \
-  (z80_cycle_aim - z80_cyclesLeft)
+  (timing.z80c_aim - z80_cyclesLeft)
 
-#define cycles_68k_to_z80(x) ((x)*957 >> 11)
+#define cycles_68k_to_z80(x) ((x) * 3823 >> 13)
 
 // ----------------------- SH2 CPU -----------------------
 
@@ -599,6 +592,15 @@ struct Pico32xMem
   unsigned short pwm_fifo[2][4];        // [0] - current raw, others - fifo entries
 };
 
+struct PicoTiming
+{
+  unsigned int m68c_frame_start;        // m68k cycles
+  unsigned int z80c_cnt;                // z80 cycles done (this frame)
+  unsigned int z80c_aim;
+  int z80_scanline;
+};
+extern struct PicoTiming timing;
+
 // area.c
 extern void (*PicoLoadStateHook)(void);
 
@@ -1092,3 +1094,4 @@ void pevt_dump(void);
 
 #endif // PICO_INTERNAL_INCLUDED
 
+// vim:shiftwidth=2:ts=2:expandtab
-- 
2.39.5