private bool ParsePragma(int lineIndex, string line, string opcode, List <string> tokens, ParserState state)
{
string pragma = opcode.ToLowerInvariant();
if (!LineSearch.MatchPragma(pragma))
{
return(false);
}
switch (pragma)
{
case ".dat8":
ParseData8(line.Replace(".dat8", string.Empty).Trim(), state);
return(true);
case ".dat16":
ParseData16(line.Replace(".dat16", string.Empty).Trim(), state);
return(true);
case ".advance":
break;
case ".alias":
{
int value;
if (tokens.Count != 3)
{
throw new Exception("alias pragma takes two parameters");
}
string alias = tokens[1];
if (!char.IsLetter(alias[0]))
{
throw new Exception("alias must begin with a letter");
}
if (alias.Any(t => !char.IsLetterOrDigit(t)))
{
throw new Exception("alias must be composed of letters and digits");
}
tokens[2] = tokens[2].Replace("$", "0x");
object convertFromString = new Int32Converter().ConvertFromString(tokens[2]);
if (convertFromString != null)
{
value = (int)convertFromString;
}
else
{
throw new Exception("alias pragma - ushort parameter must be an unsigned 16-bit integer");
}
Scopes.Scope scope = state.Scopes.GetLastOpenScope();
scope.AddAlias(alias, (ushort)value);
return(true);
}
case ".alignglobals":
{
int value;
if (tokens.Count != 2)
{
throw new Exception("alignglobals pragma takes a single parameter");
}
if (!int.TryParse(tokens[1], out value))
{
throw new Exception("alignglobals pragma parameter must be an integer");
}
if (value < 1 || value > 4)
{
throw new Exception("alignglobals pragma parameter must be an integer between 1 and 4");
}
m_Alignment = value;
return(true);
}
case ".checkpc":
break;
case ".org":
break;
case ".incbin":
return(IncludeBinary(tokens, state));
case ".include":
return(IncludeAsm(tokens, state));
case ".macro":
break;
case ".macend":
break;
case ".require":
break;
case ".reserve":
break;
case ".scope":
case "{":
state.Scopes.ScopeOpen(state.Code.Count, lineIndex);
return(true);
case ".scend":
case "}":
return(state.Scopes.ScopeClose(state.Code.Count));
}
throw new Exception($"Unimplemented pragma in line {line}");
}
private void AssembleLine(int lineIndex, string line, ParserState state)
{
line = line.Trim();
if (LineSearch.MatchLabel(line))
{
if (!state.Scopes.IsScopeOpen) // global scope
{
while ((state.Code.Count % m_Alignment) != 0)
{
state.Code.Add(0x00);
}
}
// parse label and determine if there is anything else to parse on this line.
int remaiderLineContentIndex = ParseLabel(line, state);
if (remaiderLineContentIndex <= 0)
{
return;
}
// if there is something left to parse, trim it and then interpret it as its own line.
line = line.Remove(0, remaiderLineContentIndex).Trim();
if (line.Length == 0)
{
return;
}
}
List <string> tokens = Tokenize(line);
string opcode = tokens[0];
opcode = opcode.Trim();
if (ParsePragma(lineIndex, line, opcode, tokens, state))
{
// Successfully parsed a pragma, no need to continue with this line.
return;
}
OpcodeFlag opcodeFlag = OpcodeFlag.BitWidth16; // default to operating on 16 bits
// Look for flags on operands (xxx.yyy, where y is the flag).
if (opcode.IndexOf('.') != -1 && (opcode.IndexOf('.') > 1) && (opcode.Length - opcode.IndexOf('.') - 1 > 0))
{
// opcode has a flag
string flag = opcode.Substring(opcode.IndexOf('.') + 1);
if (!ParseOpcodeFlag(flag, ref opcodeFlag))
{
throw new Exception($"Unknown bit width flag '{flag}' for instruction '{line}'");
}
opcode = opcode.Substring(0, opcode.IndexOf('.'));
}
// get the assembler for this opcode. If no assembler exists, throw error.
Func <List <string>, OpcodeFlag, ParserState, List <ushort> > assembler;
if (m_Opcodes.ContainsKey(opcode.ToLowerInvariant()))
{
assembler = m_Opcodes[opcode.ToLowerInvariant()];
}
else
{
throw new Exception($"Undefined instruction in line \"{line}\"");
}
// get the parameters
List <string> param = new List <string>();
for (int i = 1; i < tokens.Count; i++)
{
param.Add(tokens[i].Trim());
}
// pass the params to the opcode's assembler. If no output, throw error.
List <ushort> code = assembler(param, opcodeFlag, state);
if (code == null)
{
throw new Exception($"Error assembling line {line}");
}
// add the output of the assembler to the machine code output.
for (int i = 0; i < code.Count; i++)
{
ushort this_opcode = code[i];
state.Code.Add((byte)(this_opcode & 0x00ff));
state.Code.Add((byte)((this_opcode & 0xff00) >> 8));
}
}
