protected override bool ExecutePatch()
{
if (base.PC == 0xFFD2) // CHROUT
{
CBM_Console.WriteChar((char)A);
// fall through to draw character in screen memory too
}
else if (base.PC == 0xFFCF) // CHRIN
{
A = CBM_Console.ReadChar();
// SetA equivalent for flags
Z = (A == 0);
N = ((A & 0x80) != 0);
C = false;
// RTS equivalent
byte lo = base.Pop();
byte hi = base.Pop();
base.PC = (ushort)(((hi << 8) | lo) + 1);
return(true); // overriden, so don't execute
}
return(false); // execute normally
}
protected override bool ExecutePatch()
{
if (base.PC == (ushort)(memory[0xFFFC] | (memory[0xFFFD] << 8)))
{
CBM_Console.WriteChar((char)147, true); // PET 2001 doesn't initialize screen with chr$(147), so must do it here, supressing next home
}
else if (base.PC == 0xFFD2) // CHROUT
{
CBM_Console.WriteChar((char)A);
// fall through to draw character in screen memory too
}
else if (base.PC == 0xFFCF) // CHRIN
{
A = CBM_Console.ReadChar();
// SetA equivalent for flags
Z = (A == 0);
N = ((A & 0x80) != 0);
C = false;
// RTS equivalent
byte lo = base.Pop();
byte hi = base.Pop();
base.PC = (ushort)(((hi << 8) | lo) + 1);
return(true); // overriden, so don't execute
}
return(false); // execute normally
}
protected override bool ExecutePatch()
{
if (PC == 0xFFD2) // CHROUT
{
CBM_Console.WriteChar((char)A);
// fall through to draw character in screen memory too
}
else if (PC == 0xFFCF) // CHRIN
{
A = CBM_Console.ReadChar();
// SetA equivalent for flags
Z = (A == 0);
N = ((A & 0x80) != 0);
C = false;
// RTS equivalent
byte lo = Pop();
byte hi = Pop();
PC = (ushort)(((hi << 8) | lo) + 1);
return(true); // overriden, and PC changed, so caller should reloop before execution to allow breakpoint/trace/ExecutePatch/etc.
}
else if (PC == 0xA474 || PC == LOAD_TRAP) // READY
{
if (StartupPRG != null) // User requested program be loaded at startup
{
bool is_basic;
if (PC == LOAD_TRAP)
{
is_basic = (
FileVerify == false &&
FileSec == 0 && // relative load, not absolute
LO(FileAddr) == memory[43] && // requested load address matches BASIC start
HI(FileAddr) == memory[44]);
byte err;
if (!FileLoad(out err))
{
System.Diagnostics.Debug.WriteLine(string.Format("FileLoad() failed: err={0}, file {1}", err, StartupPRG));
C = true; // signal error
A = err; // FILE NOT FOUND or VERIFY
// so doesn't repeat
StartupPRG = null;
LOAD_TRAP = -1;
return(true); // overriden, and PC changed, so caller should reloop before execution to allow breakpoint/trace/ExecutePatch/etc.
}
}
else
{
is_basic = ((C64Memory)memory).LoadStartupPrg(StartupPRG, out FileAddr);
}
StartupPRG = null;
if (is_basic)
{
//UNNEW that I used in late 1980s, should work well for loading a program too, probably gleaned from BASIC ROM
//listed here as reference, adapted to use in this state machine, ExecutePatch()
//ldy #0
//lda #1
//sta(43),y
//iny
//sta(43),y
//jsr $a533 ; LINKPRG
//clc
//lda $22
//adc #2
//sta 45
//lda $23
//adc #0
//sta 46
//lda #0
//jsr $a65e ; CLEAR/CLR
//jmp $a474 ; READY
// initialize first couple bytes (may only be necessary for UNNEW?)
ushort addr = (ushort)(memory[43] | (memory[44] << 8));
memory[addr] = 1;
memory[(ushort)(addr + 1)] = 1;
// JSR equivalent
ushort retaddr = (ushort)(PC - 1);
Push(HI(retaddr));
Push(LO(retaddr));
PC = 0xA533; // LINKPRG
startup_state = 1; // should be able to regain control when returns...
return(true); // overriden, and PC changed, so caller should reloop before execution to allow breakpoint/trace/ExecutePatch/etc.
}
else
{
LOAD_TRAP = -1;
X = LO(FileAddr);
Y = HI(FileAddr);
C = false;
}
}
else if (startup_state == 1)
{
ushort addr = (ushort)(memory[0x22] | (memory[0x23] << 8) + 2);
memory[45] = (byte)addr;
memory[46] = (byte)(addr >> 8);
// JSR equivalent
ushort retaddr = (ushort)(PC - 1);
Push(HI(retaddr));
Push(LO(retaddr));
PC = 0xA65E; // CLEAR/CLR
A = 0;
startup_state = 2; // should be able to regain control when returns...
return(true); // overriden, and PC changed, so caller should reloop before execution to allow breakpoint/trace/ExecutePatch/etc.
}
else if (startup_state == 2)
{
if (PC == LOAD_TRAP)
{
X = LO(FileAddr);
Y = HI(FileAddr);
}
else
{
CBM_Console.Push("RUN\r");
PC = 0xA47B; // skip READY message, but still set direct mode, and continue to MAIN
}
C = false; // signal success
startup_state = 0;
LOAD_TRAP = -1;
return(true); // overriden, and PC changed, so caller should reloop before execution to allow breakpoint/trace/ExecutePatch/etc.
}
}
else if (PC == 0xF13E) // GETIN
{
//BASIC TEST:
//10 GET K$ : REM GETIN
//20 IF K$<> "" THEN PRINT ASC(K$)
//25 IF K$= "Q" THEN END
//30 GOTO 10
A = CBM_Console.GetIn();
if (A == 0)
{
Z = true;
C = false;
}
else
{
X = A;
Z = false;
C = false;
}
// RTS equivalent
byte lo = Pop();
byte hi = Pop();
PC = (ushort)(((hi << 8) | lo) + 1);
return(true); // overriden, and PC changed, so caller should reloop before execution to allow breakpoint/trace/ExecutePatch/etc.
}
else if (PC == 0xF6ED) // STOP
{
Z = CBM_Console.CheckStop();
// RTS equivalent
byte lo = Pop();
byte hi = Pop();
PC = (ushort)(((hi << 8) | lo) + 1);
return(true); // overriden, and PC changed, so caller should reloop before execution to allow breakpoint/trace/ExecutePatch/etc.
}
else if (PC == 0xFE00) // SETLFS
{
FileNum = A;
FileDev = X;
FileSec = Y;
System.Diagnostics.Debug.WriteLine(string.Format("SETLFS {0},{1},{2}", FileNum, FileDev, FileSec));
}
else if (PC == 0xFDF9) // SETNAM
{
StringBuilder name = new StringBuilder();
ushort addr = (ushort)(X + (Y << 8));
for (int i = 0; i < A; ++i)
{
name.Append((char)memory[(ushort)(addr + i)]);
}
System.Diagnostics.Debug.WriteLine(string.Format("SETNAM {0}", name.ToString()));
FileName = name.ToString();
}
else if (PC == 0xF49E) // LOAD
{
FileAddr = (ushort)(X + (Y << 8));
string op;
if (A == 0)
{
op = "LOAD";
}
else if (A == 1)
{
op = "VERIFY";
}
else
{
op = string.Format("LOAD (A={0}) ???", A);
}
FileVerify = (A == 1);
System.Diagnostics.Debug.WriteLine(string.Format("{0} @{1:X4}", op, FileAddr));
// RTS equivalent
byte lo = Pop();
byte hi = Pop();
PC = (ushort)(((hi << 8) | lo) + 1);
if (A == 0 || A == 1)
{
StartupPRG = FileName;
FileName = null;
LOAD_TRAP = PC;
// Set success
C = false;
}
else
{
A = 14; // ILLEGAL QUANTITY message
C = true; // failure
}
return(true); // overriden, and PC changed, so caller should reloop before execution to allow breakpoint/trace/ExecutePatch/etc.
}
else if (PC == 0xF5DD) // SAVE
{
ushort addr1 = (ushort)(memory[A] + (memory[(ushort)(A + 1)] << 8));
ushort addr2 = (ushort)(X + (Y << 8));
System.Diagnostics.Debug.WriteLine(string.Format("SAVE {0:X4}-{1:X4}", addr1, addr2));
// RTS equivalent
byte lo = Pop();
byte hi = Pop();
PC = (ushort)(((hi << 8) | lo) + 1);
// Set success
C = !FileSave(FileName, addr1, addr2);
return(true); // overriden, and PC changed, so caller should reloop before execution to allow breakpoint/trace/ExecutePatch/etc.
}
return(false); // execute normally
}