word RunZ80(Z80 *R)
{
register byte I;
register pair J;
for(;;)
{
#ifdef DEBUG
/* Turn tracing on when reached trap address */
if(R->PC.W==R->Trap) R->Trace=1;
/* Call single-step debugger, exit if requested */
if(R->Trace)
if(!DebugZ80(R)) return(R->PC.W);
#endif
I=RdZ80(R->PC.W++);
R->ICount-=Cycles[I];
switch(I)
{
#include "Codes.h"
case PFX_CB: CodesCB(R);break;
case PFX_ED: CodesED(R);break;
case PFX_FD: CodesFD(R);break;
case PFX_DD: CodesDD(R);break;
}
/* If cycle counter expired... */
if(R->ICount<=0)
{
/* If we have come after EI, get address from IRequest */
/* Otherwise, get it from the loop handler */
if(R->IFF&IFF_EI)
{
R->IFF=(R->IFF&~IFF_EI)|IFF_1; /* Done with AfterEI state */
R->ICount+=R->IBackup-1; /* Restore the ICount */
/* Call periodic handler or set pending IRQ */
if(R->ICount>0) J.W=R->IRequest;
else
{
J.W=LoopZ80(R); /* Call periodic handler */
R->ICount+=R->IPeriod; /* Reset the cycle counter */
if(J.W==INT_NONE) J.W=R->IRequest; /* Pending IRQ */
}
}
else
{
J.W=LoopZ80(R); /* Call periodic handler */
R->ICount+=R->IPeriod; /* Reset the cycle counter */
if(J.W==INT_NONE) J.W=R->IRequest; /* Pending IRQ */
}
if(J.W==INT_QUIT) return(R->PC.W); /* Exit if INT_QUIT */
if(J.W!=INT_NONE) IntZ80(R,J.W); /* Int-pt if needed */
}
}
/* Execution stopped */
return(R->PC.W);
}
int ExecZ80(register Z80 *R,register int RunCycles)
{
register byte I;
register pair J;
for(R->ICount=RunCycles;;)
{
while(R->ICount>0)
{
#ifdef DEBUG
/* Turn tracing on when reached trap address */
if(R->PC.W==R->Trap) R->Trace=1;
/* Call single-step debugger, exit if requested */
if(R->Trace)
if(!DebugZ80(R)) return(R->ICount);
#endif
/* Read opcode and count cycles */
I=OpZ80(R->PC.W++);
/* Count cycles */
R->ICount-=Cycles[I];
/* Interpret opcode */
switch(I)
{
#include "Codes.h"
case PFX_CB: CodesCB(R);break;
case PFX_ED: CodesED(R);break;
case PFX_FD: CodesFD(R);break;
case PFX_DD: CodesDD(R);break;
}
/* Unless we have come here after EI, exit */
if(!(R->IFF&IFF_EI))
{
/* Interrupt CPU if needed */
if((R->IRequest!=INT_NONE)&&(R->IRequest!=INT_QUIT)) IntZ80(R,R->IRequest);
}
else
{
/* Done with AfterEI state */
R->IFF=(R->IFF&~IFF_EI)|IFF_1;
/* Restore the ICount */
R->ICount+=R->IBackup-1;
}
}
return(R->ICount);
}
}
word RunZ80(Z80 *R)
{
register byte I;
register pair J;
for(;;)
{
#ifdef DEBUG
/* Turn tracing on when reached trap address */
if(R->PC.W==R->Trap) R->Trace=1;
/* Call single-step debugger, exit if requested */
if(R->Trace)
if(!DebugZ80(R)) return(R->PC.W);
#endif
I=OpZ80(R->PC.W++);
R->ICount-=Cycles[I];
switch(I)
{
#include "Codes.h"
case PFX_CB: CodesCB(R);break;
case PFX_ED: CodesED(R);break;
case PFX_FD: CodesFD(R);break;
case PFX_DD: CodesDD(R);break;
}
/* Nascom Single Step
; activate nmi
push af
ld a,8
out (0),a
pop af
; execute one step of program
retn
after out skip pop,retn and one user program opcode
before forcing NMI */
byte skip;
if (R->Trap)
{
if (skip++==3)
{
skip=0;
R->Trap=0;
IntZ80(R,INT_NMI);
}
}
/* If cycle counter expired... */
if(R->ICount<=0)
{
/* If we have come after EI, get address from IRequest */
/* Otherwise, get it from the loop handler */
if(R->IFF&IFF_EI)
{
R->IFF=(R->IFF&~IFF_EI)|IFF_1; /* Done with AfterEI state */
R->ICount+=R->IBackup-1; /* Restore the ICount */
/* Call periodic handler or set pending IRQ */
if(R->ICount>0) J.W=R->IRequest;
else
{
J.W=LoopZ80(R); /* Call periodic handler */
R->ICount+=R->IPeriod; /* Reset the cycle counter */
if(J.W==INT_NONE) J.W=R->IRequest; /* Pending IRQ */
}
}
else
{
J.W=LoopZ80(R); /* Call periodic handler */
R->ICount+=R->IPeriod; /* Reset the cycle counter */
if(J.W==INT_NONE) J.W=R->IRequest; /* Pending IRQ */
}
if(J.W==INT_QUIT) return(R->PC.W); /* Exit if INT_QUIT */
if(J.W!=INT_NONE) IntZ80(R,J.W); /* Int-pt if needed */
}
}
/* Execution stopped */
return(R->PC.W);
}
