From 274dd51a6084a1d485d5efa6c52239434bdd2b08 Mon Sep 17 00:00:00 2001
From: kub <derkub@gmail.com>
Date: Tue, 7 May 2024 23:10:27 +0200
Subject: [PATCH] core z80, cycle counting fixes (reset, bus request)

---
 pico/cd/mcd.c   |  2 +-
 pico/debug.c    |  2 +-
 pico/memory.c   | 12 +++++++-----
 pico/pico_cmn.c |  4 ++--
 pico/pico_int.h |  4 ++--
 pico/sms.c      |  2 +-
 6 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/pico/cd/mcd.c b/pico/cd/mcd.c
index 2fdbe725..60acd6df 100644
--- a/pico/cd/mcd.c
+++ b/pico/cd/mcd.c
@@ -312,7 +312,7 @@ static int SekSyncM68k(int once);
 void pcd_run_cpus_normal(int m68k_cycles)
 {
   // TODO this is suspicious. ~1 cycle refresh delay every 256 cycles?
-  SekAimM68k(m68k_cycles, 0x43); // Fhey area
+  SekAimM68k(m68k_cycles, 0x42); // Fhey area
 
   while (CYCLES_GT(Pico.t.m68c_aim, Pico.t.m68c_cnt)) {
     if (SekShouldInterrupt()) {
diff --git a/pico/debug.c b/pico/debug.c
index 5a85a30a..064e97a9 100644
--- a/pico/debug.c
+++ b/pico/debug.c
@@ -389,7 +389,6 @@ void PDebugZ80Frame(void)
   else
     lines = 262;
 
-  z80_resetCycles(Pico.t.z80c_aim);
   PsndStartFrame();
 
   if (/*Pico.m.z80Run &&*/ !Pico.m.z80_reset && (PicoIn.opt&POPT_EN_Z80)) {
@@ -407,6 +406,7 @@ void PDebugZ80Frame(void)
     PsndGetSamples(lines);
 
   timers_cycle(Pico.t.z80c_aim);
+  z80_resetCycles();
   Pico.t.m68c_aim = Pico.t.m68c_cnt;
 }
 
diff --git a/pico/memory.c b/pico/memory.c
index 1bd230d0..0c06acae 100644
--- a/pico/memory.c
+++ b/pico/memory.c
@@ -530,20 +530,21 @@ void NOINLINE ctl_write_z80busreq(u32 d)
   {
     if (d)
     {
-      Pico.t.z80c_cnt = z80_cycles_from_68k() + (Pico.t.z80_busdelay >> 8);
+      Pico.t.z80c_aim = Pico.t.z80c_cnt = z80_cycles_from_68k() + (Pico.t.z80_busdelay >> 8) + 2;
       Pico.t.z80_busdelay &= 0xff;
     }
     else
     {
       if ((PicoIn.opt & POPT_EN_Z80) && !Pico.m.z80_reset) {
-        // Z80 grants bus 2 cycles after the next M cycle, even within an insn
+        // Z80 grants bus after the current M cycle, even within an insn
         // simulate this by accumulating the last insn overhang in busdelay
-        unsigned granted = z80_cycles_from_68k() + 6;
+        unsigned granted;
         pprof_start(m68k);
         PicoSyncZ80(SekCyclesDone());
+        pprof_end_sub(m68k);
+        granted = Pico.t.z80c_aim + 6; // M cycle is 3-6 cycles 
         Pico.t.z80_busdelay += (Pico.t.z80c_cnt - granted) << 8;
         Pico.t.z80c_cnt = granted;
-        pprof_end_sub(m68k);
       }
     }
     Pico.m.z80Run = d;
@@ -563,12 +564,13 @@ void NOINLINE ctl_write_z80reset(u32 d)
         PicoSyncZ80(SekCyclesDone());
         pprof_end_sub(m68k);
       }
+      Pico.t.z80_busdelay &= 0xff; // also resets bus request
       YM2612ResetChip();
       timers_reset();
     }
     else
     {
-      Pico.t.z80c_cnt = z80_cycles_from_68k() + 2;
+      Pico.t.z80c_aim = Pico.t.z80c_cnt = z80_cycles_from_68k() + 2;
       z80_reset();
     }
     Pico.m.z80_reset = d;
diff --git a/pico/pico_cmn.c b/pico/pico_cmn.c
index 519aba35..af2e598c 100644
--- a/pico/pico_cmn.c
+++ b/pico/pico_cmn.c
@@ -81,7 +81,7 @@ static __inline void SekAimM68k(int cyc, int mult)
 static __inline void SekRunM68k(int cyc)
 {
   // TODO 0x100 would be 2 cycles/128, moreover far too sensitive
-  SekAimM68k(cyc, 0x10c); // OutRunners, testpico, VDPFIFOTesting
+  SekAimM68k(cyc, 0x108); // OutRunners, testpico, VDPFIFOTesting
   SekSyncM68k(0);
 }
 
@@ -141,7 +141,6 @@ static int PicoFrameHints(void)
 
   skip = PicoIn.skipFrame;
 
-  z80_resetCycles(cycles_68k_to_z80(Pico.t.m68c_aim - Pico.t.m68c_frame_start));
   Pico.t.m68c_frame_start = Pico.t.m68c_aim;
   PsndStartFrame();
 
@@ -340,6 +339,7 @@ static int PicoFrameHints(void)
   PsndGetSamples(y);
 
   timers_cycle(cycles_68k_to_z80(Pico.t.m68c_aim - Pico.t.m68c_frame_start));
+  z80_resetCycles();
 
   pv->hint_cnt = hint;
 
diff --git a/pico/pico_int.h b/pico/pico_int.h
index fbdeb873..995f8c16 100644
--- a/pico/pico_int.h
+++ b/pico/pico_int.h
@@ -201,8 +201,8 @@ extern struct DrZ80 drZ80;
 
 #define Z80_STATE_SIZE 0x60
 
-#define z80_resetCycles(aim) \
-  Pico.t.z80c_cnt -= (aim < Pico.t.z80c_cnt ? aim : Pico.t.z80c_cnt), Pico.t.z80c_aim = Pico.t.z80_scanline = 0
+#define z80_resetCycles() \
+  Pico.t.z80c_cnt -= Pico.t.z80c_aim, Pico.t.z80c_aim = Pico.t.z80_scanline = 0
 
 #define z80_cyclesDone() \
   (Pico.t.z80c_aim - z80_cyclesLeft)
diff --git a/pico/sms.c b/pico/sms.c
index e954bc8b..c56111c8 100644
--- a/pico/sms.c
+++ b/pico/sms.c
@@ -846,7 +846,6 @@ void PicoFrameMS(void)
   int nmi;
   int y;
 
-  z80_resetCycles(Pico.t.z80c_aim);
   PsndStartFrame();
 
   // for SMS the pause button generates an NMI, for GG ths is not the case
@@ -923,6 +922,7 @@ void PicoFrameMS(void)
     z80_exec(Pico.t.z80c_line_start + cycles_line);
   }
 
+  z80_resetCycles();
   PsndGetSamplesMS(lines);
 }
 
-- 
2.39.5