private void SaveWordString(int offset, ushort data)
{
int addr = (ES << 4) + offset;
WordRegister reg = new WordRegister(data);
Ram[addr + 1] = reg.HI;
Ram[addr] = reg.LO;
}
private void MoveWordString(int src_offset, int dst_offset)
{
int dst_addr = (ES << 4) + dst_offset;
WordRegister data = new WordRegister(GetWord(src_offset));
Ram[dst_addr + 1] = data.HI;
Ram[dst_addr] = data.LO;
}
// save the 16 bit value to the requested offset
private void SaveWord(int offset, ushort value)
{
int addr = (GetDataSegment() << 4) + offset;
if (addr >= MAX_MEMORY)
{
throw new InvalidOperationException(String.Format("Memory bounds exceeded. DS={0:X4} offset={1:X4}", DS, offset));
}
WordRegister data = new WordRegister(value);
Ram[addr + 1] = data.HI;
Ram[addr] = data.LO;
}
public void PushStack(int offset, ushort value)
{
int addr = (SS << 4) + offset;
if (addr >= MAX_MEMORY)
{
throw new InvalidOperationException(String.Format("Memory bounds exceeded. SS={0:X4} offset={1:X4}", SS, offset));
}
WordRegister reg = new WordRegister(value);
Ram[addr + 1] = reg.HI;
Ram[addr] = reg.LO;
}
public static uint DisassembleNext(byte[] buffer, uint pc, ushort startingAddress, out string output)
{
// formatting note: immediate data does not get brackets
// data from memory or calculations get brackets
// something went terribly wrong
if (buffer.Length <= pc)
{
throw new IndexOutOfRangeException("Index pc exceeds the bounds of the buffer");
}
uint bytes_read = 1;
byte op = buffer[pc];
OpCodeDasmRecord op_table = OpCodeDasmTable.opCodes[op];
output = "";
// if there is no entry for this code in the op_table it is unused
if (op_table.op_name == "")
{
output = "UNDEFINED OP CODE " + op.ToString("X2");
}
// if there is no info for the 2nd byte then it is a one byte op code with a static string
else if (op_table.addr_byte == "")
{
output = op_table.op_name;
}
// Otherwise use the addr_byte format to determine next steps
// Possible values: A-LO, D-8, D-LO, IP-INC-8, IP-INC-LO, IP-LO, MRR
// A-LO: 2nd & 3rd bytes point to data at a memory location
else if (op_table.addr_byte == "A-LO")
{
WordRegister reg21 = new WordRegister(buffer[pc + 2], buffer[pc + 1]);
bytes_read += 2;
if (op_table.op_fmt_1.StartsWith("M-"))
{
output = string.Format("{0} [{1}],{2}", op_table.op_name,
reg21.ToString(),
op_table.op_fmt_2);
}
else
{
output = string.Format("{0} {1},[{2}]", op_table.op_name,
op_table.op_fmt_1,
reg21.ToString());
}
}
// The 2nd byte is 8 bit immediate data
else if (op_table.addr_byte == "D-8")
{
bytes_read++; // these are two byte instructions
if (op_table.op_fmt_1 == "I-8")
{
if (op_table.op_fmt_2 == "")
{
output = string.Format("{0} {1}", op_table.op_name, buffer[pc + 1].ToString("X2"));
}
else
{
output = string.Format("{0} {1},{2}", op_table.op_name, buffer[pc + 1].ToString("X2"), op_table.op_fmt_2);
}
}
else
{
output = string.Format("{0} {1},{2}", op_table.op_name, op_table.op_fmt_1, buffer[pc + 1].ToString("X2"));
}
}
// D-LO: 2nd & 3rd bytes are 16 bit immediate data
else if (op_table.addr_byte == "D-LO")
{
WordRegister reg21 = new WordRegister(buffer[pc + 2], buffer[pc + 1]);
bytes_read += 2; // these are three byte instructions
if (op_table.op_fmt_1 == "I-16")
{
output = string.Format("{0} {1}", op_table.op_name,
reg21.ToString());
}
else if (op_table.op_fmt_1 == "FAR")
{
WordRegister reg43 = new WordRegister(buffer[pc + 4], buffer[pc + 3]);
output = string.Format("{0} {1}:{2}", op_table.op_name,
reg43.ToString(),
reg21.ToString());
bytes_read += 2; // two additional bytes
}
else
{
output = string.Format("{0} {1},{2}", op_table.op_name, op_table.op_fmt_1,
reg21.ToString());
}
}
// IP-INC-8: Add the 8 bit number to the value of the program counter for the next instruction
else if (op_table.addr_byte == "IP-INC-8")
{
uint immediate = (pc + 2) + buffer[pc + 1];
bytes_read++; // two byte instruction
output = string.Format("{0} {1} {2}", op_table.op_name, op_table.op_fmt_1, immediate.ToString("X4"));
}
// IP-INC-LO: 2nd & 3rd bytes are 16 bites of immediate data to be added to the program counter of the
// next instruction
else if (op_table.addr_byte == "IP-INC-LO")
{
WordRegister reg21 = new WordRegister(buffer[pc + 2], buffer[pc + 1]);
uint immediate = (pc + 3) + reg21;
bytes_read += 2; // three byte instruction
output = string.Format("{0} {1}", op_table.op_name, immediate.ToString("X4"));
}
// IP-LO: next 4 bytes are IP-LO, IP-HI, CS-LO, CS-HI
else if (op_table.addr_byte == "IP-LO")
{
bytes_read += 4; // five byte instruction
WordRegister reg21 = new WordRegister(buffer[pc + 2], buffer[pc + 1]);
WordRegister reg43 = new WordRegister(buffer[pc + 4], buffer[pc + 3]);
output = string.Format("{0} {1}:{2}", op_table.op_name, reg43.ToString(), reg21.ToString());
}
// MRR: the biggie
else if (op_table.addr_byte == "MRR")
{
byte addr_mode = buffer[pc + 1];
bytes_read++;
// possible formatting values:
// M-8, M-16, I-8, I-16, R-8, R-16, RM-8, RM-16, SEG
string oper1 = "";
string oper2 = "";
string oper1_fmt = GetFirstOper(buffer, pc);
if (oper1_fmt == "RM-8" || oper1_fmt == "M-8")
{
bytes_read += DisassembleRM(buffer, pc, 1, GetMOD(addr_mode), GetRM(addr_mode), 0, out oper1);
}
else if (oper1_fmt == "RM-16" || oper1_fmt == "M-16")
{
bytes_read += DisassembleRM(buffer, pc, 1, GetMOD(addr_mode), GetRM(addr_mode), 1, out oper1);
}
else if (oper1_fmt == "R-8")
{
oper1 = RegField[GetREG(buffer, pc), 0];
}
else if (oper1_fmt == "R-16")
{
oper1 = RegField[GetREG(buffer, pc), 1];
}
else if (oper1_fmt == "SEG")
{
oper1 = SegRegTable[GetREG(buffer, pc)];
}
else if (oper1_fmt == "I-8")
{
oper1 = buffer[pc + 2].ToString("X2");
bytes_read++;
}
else if (oper1_fmt == "I-16")
{
oper1 = buffer[pc + 3].ToString("X2") + buffer[pc + 2].ToString("X2");
bytes_read += 2;
}
else if (oper1_fmt != "")
{
oper1 = oper1_fmt;
}
uint immed_offset = bytes_read - 1;
if (!SkipSecondOper(buffer, pc))
{
if (op_table.op_fmt_2 == "RM-8" || op_table.op_fmt_2 == "M-8")
{
bytes_read += DisassembleRM(buffer, pc, immed_offset, GetMOD(addr_mode), GetRM(addr_mode), 0, out oper2);
}
else if (op_table.op_fmt_2 == "RM-16" || op_table.op_fmt_2 == "M-16")
{
bytes_read += DisassembleRM(buffer, pc, immed_offset, GetMOD(addr_mode), GetRM(addr_mode), 1, out oper2);
}
else if (op_table.op_fmt_2 == "R-8")
{
oper2 = RegField[GetREG(buffer, pc), 0];
}
else if (op_table.op_fmt_2 == "R-16")
{
oper2 = RegField[GetREG(buffer, pc), 1];
}
else if (op_table.op_fmt_2 == "SEG")
{
oper2 = SegRegTable[GetREG(buffer, pc)];
}
else if (op_table.op_fmt_2 == "I-8")
{
oper2 = buffer[pc + immed_offset + 1].ToString("X2");
bytes_read++;
}
else if (op_table.op_fmt_2 == "I-16")
{
oper2 = buffer[pc + immed_offset + 2].ToString("X2") + buffer[pc + immed_offset + 1].ToString("X2");
bytes_read += 2;
}
else if (op_table.op_fmt_2 != "")
{
oper2 = op_table.op_fmt_2;
}
}
if (oper2 == "")
{
output = string.Format("{0} {1}", GetOpName(op, GetREG(buffer, pc)), oper1);
}
else
{
output = string.Format("{0} {1},{2}", GetOpName(op, GetREG(buffer, pc)), oper1, oper2);
}
}
output = output.ToLower();
return(bytes_read);
}