better CPU_IRQSTATUS_HOLD for z80

src/cpu/z80/z80.cpp

@@ -193,6 +193,7 @@ unsigned char Z80Vector = 0xff;
 int z80_ICount;
 static Z80_Regs Z80;
 UINT32 EA;
+int z80_hold_hack;
 
 static UINT8 SZ[256];		/* zero and sign flags */
 static UINT8 SZ_BIT[256];	/* zero, sign and parity/overflow (=zero) flags for BIT opcode */
@@ -3324,6 +3325,11 @@ static void take_interrupt(void)
 //	else
 //		irq_vector = (*Z80.irq_callback)(0);
 
+	if (z80_hold_hack) {
+		z80_hold_hack = 0;
+		Z80.irq_state = 0;
+	}
+
 //	LOG(("Z80 #%d single int. irq_vector $%02x\n", cpu_getactivecpu(), irq_vector));
 
 	/* Interrupt mode 2. Call [Z80.i:databyte] */
@@ -3473,6 +3479,7 @@ void Z80Init()
 
 	/* Reset registers to their initial values */
 	memset(&Z80, 0, sizeof(Z80));
+	z80_hold_hack = 0;
 //	Z80.daisy = config;
 //	Z80.irq_callback = irqcallback;
 	IX = IY = 0xffff; /* IX and IY are FFFF after a reset! */
@@ -3485,6 +3492,7 @@ void Z80Reset()
 	//int (*irq_callback)(int irqline);
 
 	memset(&Z80, 0, sizeof(Z80));
+	z80_hold_hack = 0;
 
 	PC = 0x0000;
 	I = 0;

src/cpu/z80/z80.h

@@ -71,6 +71,7 @@ extern unsigned char Z80Vector;
 
 extern int z80_ICount;
 extern UINT32 EA;
+extern int z80_hold_hack;
 
 typedef unsigned char (__fastcall *Z80ReadIoHandler)(unsigned int a);
 typedef void (__fastcall *Z80WriteIoHandler)(unsigned int a, unsigned char v);

src/cpu/z80_intf.cpp

@@ -687,10 +687,11 @@ void ZetSetIRQLine(const INT32 line, const INT32 status)
 			Z80Execute(0);
 			break;
 		case CPU_IRQSTATUS_HOLD:
+			z80_hold_hack = 1;
 			Z80SetIrqLine(line, 1);
-			Z80Execute(100);
-			Z80SetIrqLine(0, 0);
-			Z80Execute(0);
+			//Z80Execute(100);
+			//Z80SetIrqLine(0, 0);
+			//Z80Execute(0);
 			break;
 	}
 }