From d919f3865c33a0002cd3b78081720bdb12eed24b Mon Sep 17 00:00:00 2001
From: toxieainc <toxie@ainc.de>
Date: Mon, 18 Jul 2022 22:45:23 +0200
Subject: [PATCH] port some changes from MAME/MESS

---
 Src/CPU/Z80/Z80.cpp | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/Src/CPU/Z80/Z80.cpp b/Src/CPU/Z80/Z80.cpp
index 370f94c..3967ffd 100644
--- a/Src/CPU/Z80/Z80.cpp
+++ b/Src/CPU/Z80/Z80.cpp
@@ -2698,7 +2698,7 @@ int CZ80::Run(int numCycles)
       break;
     case 0x71:      /* OUT (C),0 */
       cycles -= cycleTables[2][0x71];
-      OUTPUT(lreg(BC), 0);
+      OUTPUT(lreg(BC), lreg(0));
       break;
     case 0x72:      /* SBC HL,SP */
       cycles -= cycleTables[2][0x72];
@@ -2821,6 +2821,8 @@ int CZ80::Run(int numCycles)
       cycles -= cycleTables[2][0xB0];
       acu = hreg(AF);
       BC &= 0xffff;
+      if (BC == 0)
+        BC = 0x10000;
       do {
         acu = GetBYTE_pp(HL);
         PutBYTE_pp(DE, acu);
@@ -2832,6 +2834,8 @@ int CZ80::Run(int numCycles)
       cycles -= cycleTables[2][0xB1];
       acu = hreg(AF);
       BC &= 0xffff;
+      if (BC == 0)
+        BC = 0x10000;
       do {
         temp = GetBYTE_pp(HL);
         op = --BC != 0;
@@ -2868,6 +2872,8 @@ int CZ80::Run(int numCycles)
     case 0xB8:      /* LDDR */
       cycles -= cycleTables[2][0xB8];
       BC &= 0xffff;
+      if (BC == 0)
+        BC = 0x10000;
       do {
         acu = GetBYTE_mm(HL);
         PutBYTE_mm(DE, acu);
@@ -2879,6 +2885,8 @@ int CZ80::Run(int numCycles)
       cycles -= cycleTables[2][0xB9];
       acu = hreg(AF);
       BC &= 0xffff;
+      if (BC == 0)
+        BC = 0x10000;
       do {
         temp = GetBYTE_mm(HL);
         op = --BC != 0;
@@ -3505,7 +3513,7 @@ int CZ80::Run(int numCycles)
       break;
     case 0xCB:      /* CB prefix */
       adr = IY + (signed char) GetBYTE_pp(pc);
-      adr = adr;
+      //adr = adr;
       op = GetBYTE(pc);
       cycles -= cycleTables[4][op];
       switch (op & 7) {