From 9b61ba715a2744ce276ba44530b89405a8da5b5d Mon Sep 17 00:00:00 2001
From: kub <derkub@gmail.com>
Date: Thu, 6 May 2021 22:43:31 +0200
Subject: [PATCH] mcd, improve polling detection

---
 pico/cd/mcd.c    | 36 ++++++++++++++++++++++--------------
 pico/cd/memory.c |  2 +-
 2 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/pico/cd/mcd.c b/pico/cd/mcd.c
index 255b2e97..7554f8c6 100644
--- a/pico/cd/mcd.c
+++ b/pico/cd/mcd.c
@@ -124,9 +124,6 @@ static void SekRunS68k(unsigned int to)
   if ((cyc_do = SekCycleAimS68k - SekCycleCntS68k) <= 0)
     return;
 
-  if (SekShouldInterrupt())
-    Pico_mcd->m.s68k_poll_a = 0;
-
   pprof_start(s68k);
   SekCycleCntS68k += cyc_do;
 #if defined(EMU_C68K)
@@ -317,7 +314,11 @@ int pcd_sync_s68k(unsigned int m68k_target, int m68k_poll_sync)
     if (event_time_next && CYCLES_GT(target, event_time_next))
       target = event_time_next;
 
-    SekRunS68k(target);
+    if (SekIsStoppedS68k())
+      SekCycleCntS68k = SekCycleAimS68k = target;
+    else
+      SekRunS68k(target);
+
     if (m68k_poll_sync && Pico_mcd->m.m68k_poll_cnt == 0)
       break;
   }
@@ -334,20 +335,27 @@ static void SekSyncM68k(void);
 void pcd_run_cpus_normal(int m68k_cycles)
 {
   Pico.t.m68c_aim += m68k_cycles;
-  if (SekShouldInterrupt() || Pico_mcd->m.m68k_poll_cnt < 12)
-    Pico_mcd->m.m68k_poll_cnt = 0;
-  else if (Pico_mcd->m.m68k_poll_cnt >= 16) {
-    int s68k_left = pcd_sync_s68k(Pico.t.m68c_aim, 1);
-    if (s68k_left <= 0) {
+
+  while (CYCLES_GT(Pico.t.m68c_aim, Pico.t.m68c_cnt)) {
+    if (SekShouldInterrupt())
+      Pico_mcd->m.m68k_poll_cnt = 0;
+
+#ifdef USE_POLL_DETECT
+    if (Pico_mcd->m.m68k_poll_cnt >= 16) {
+      // main CPU is polling, (wake and) run sub only
+      SekSetStopS68k(0);
+      pcd_sync_s68k(Pico.t.m68c_aim, 1);
+
+      Pico.t.m68c_cnt = Pico.t.m68c_aim;
+      if (SekIsStoppedS68k()) {
+        // slave has stopped, wake master to avoid lockups
+        Pico_mcd->m.m68k_poll_cnt = 0;
+      }
       elprintf(EL_CDPOLL, "m68k poll [%02x] x%d @%06x",
         Pico_mcd->m.m68k_poll_a, Pico_mcd->m.m68k_poll_cnt, SekPc);
-      Pico.t.m68c_cnt = Pico.t.m68c_aim;
-      return;
     }
-    Pico.t.m68c_cnt = Pico.t.m68c_aim - (s68k_left * mcd_s68k_cycle_mult >> 16);
-  }
+#endif
 
-  while (CYCLES_GT(Pico.t.m68c_aim, Pico.t.m68c_cnt)) {
     SekRunM68kOnce();
     if (Pico_mcd->m.need_sync) {
       Pico_mcd->m.need_sync = 0;
diff --git a/pico/cd/memory.c b/pico/cd/memory.c
index f3b7a16f..558251c7 100644
--- a/pico/cd/memory.c
+++ b/pico/cd/memory.c
@@ -331,7 +331,7 @@ u32 s68k_reg_read16(u32 a)
 
   d = (Pico_mcd->s68k_regs[a]<<8) | Pico_mcd->s68k_regs[a+1];
 
-  if (a >= 0x0e && a < 0x30)
+  if (a >= 0x0e && a < 0x20)
     return s68k_poll_detect(a, d);
 
   return d;
-- 
2.39.2