private static void ExecuteAlphaAssignment()
{
long?targetPos = null;
bool isBuffer = false;
targetPos = MemPos.GetPosAlpha(_tokens[_tokenNum]);
if (!targetPos.HasValue)
{
targetPos = MemPos.GetPosBufferAlpha(_tokens[_tokenNum]);
if (targetPos.HasValue)
{
isBuffer = true;
}
}
if (!targetPos.HasValue)
{
throw new SystemException("Cannot parse alpha assignment: Target not found");
}
_tokenNum++;
if (_tokens[_tokenNum] == "[")
{
_tokenNum++; // "["
long offset = GetNumericExpression();
if (_tokens[_tokenNum++] != "]")
{
throw new SystemException("ExecuteAlphaAssignment: No closing \"]\"");
}
targetPos += offset;
}
if (_tokens[_tokenNum] != "=")
{
throw new SystemException("Cannot parse alpha expression: Equals sign expected");
}
_tokenNum++;
string result = GetAlphaExpression();
if (isBuffer)
{
long bufferTargetPos = Mem.GetByte(targetPos.Value)
+ (256 * Mem.GetByte(targetPos.Value + 1));
Mem.SetAlpha(bufferTargetPos, result);
if (result == "")
{
bufferTargetPos += 1;
}
else
{
bufferTargetPos += result.Length;
}
Mem.SetByte(targetPos.Value + 1, bufferTargetPos / 256);
Mem.SetByte(targetPos.Value, bufferTargetPos % 256);
}
else
{
Mem.SetAlpha(targetPos.Value, result);
}
}
private static bool IsAlphaTarget()
{
if (MemPos.GetPosAlpha(_tokens[_tokenNum]).HasValue ||
MemPos.GetPosBufferAlpha(_tokens[_tokenNum]).HasValue)
{
if (_tokenNum < _tokenCount)
{
if (_tokens[_tokenNum + 1] == "=" ||
_tokens[_tokenNum + 1] == "[")
{
return(true);
}
}
}
return(false);
}
private static string GetAlphaExpression()
{
if (_tokenNum >= _tokenCount)
{
throw new SystemException("Cannot parse alpha expression: Unexpected end of line");
}
string result = null;
if (_tokens[_tokenNum].StartsWith("\"") ||
_tokens[_tokenNum].StartsWith("'") ||
_tokens[_tokenNum].StartsWith("$") ||
_tokens[_tokenNum].StartsWith("%"))
{
//if (_tokenNum != _tokenCount - 1)
//{
// throw new SystemException("Cannot parse alpha expression: Tokens after string literal");
//}
result = _tokens[_tokenNum].Substring(1, _tokens[_tokenNum].Length - 2);
}
else
{
long?targetPos = null;
targetPos = MemPos.GetPosAlpha(_tokens[_tokenNum++]);
if (!targetPos.HasValue)
{
throw new SystemException("Cannot parse alpha assignment: Target not found");
}
if (_tokenNum < _tokenCount && _tokens[_tokenNum] == "[")
{
_tokenNum++; // "["
long offset = GetNumericExpression();
if (_tokens[_tokenNum++] != "]")
{
throw new SystemException("GetAlphaExpression: No closing \"]\"");
}
targetPos += offset;
}
result = Mem.GetAlpha(targetPos.Value);
}
if (result == null)
{
throw new SystemException("Cannot parse alpha expression: No result");
}
return(result);
}