private static object ResolveFixupReferent(
RecordContext context, FixupTargetMethod method, UInt16 indexOrFrame)
{
switch (method)
{
case FixupTargetMethod.Absolute:
return(indexOrFrame);
case FixupTargetMethod.SegmentPlusDisplacement:
case FixupTargetMethod.SegmentWithoutDisplacement:
return(context.Segments[indexOrFrame - 1]);
case FixupTargetMethod.GroupPlusDisplacement:
case FixupTargetMethod.GroupWithoutDisplacement:
return(context.Groups[indexOrFrame - 1]);
case FixupTargetMethod.ExternalPlusDisplacement:
case FixupTargetMethod.ExternalWithoutDisplacement:
return(context.ExternalNames[indexOrFrame - 1]);
default:
throw new InvalidDataException("Invalid fixup target method: " + method);
}
}
private static object ResolveFixupReferent(
RecordContext context, FixupTargetMethod method, UInt16 indexOrFrame)
{
switch (method)
{
case FixupTargetMethod.Absolute:
return indexOrFrame;
case FixupTargetMethod.SegmentPlusDisplacement:
case FixupTargetMethod.SegmentWithoutDisplacement:
return context.Segments[indexOrFrame - 1];
case FixupTargetMethod.GroupPlusDisplacement:
case FixupTargetMethod.GroupWithoutDisplacement:
return context.Groups[indexOrFrame - 1];
case FixupTargetMethod.ExternalPlusDisplacement:
case FixupTargetMethod.ExternalWithoutDisplacement:
return context.ExternalNames[indexOrFrame - 1];
default:
throw new InvalidDataException("Invalid fixup target method: " + method);
}
}
private FixupDefinition ParseFixupSubrecord(RecordReader reader, RecordContext context)
{
FixupDefinition fixup = new FixupDefinition();
byte b1 = reader.ReadByte();
byte b2 = reader.ReadByte();
UInt16 w = (UInt16)((b1 << 8) | b2); // big endian
fixup.Mode = (w & 0x4000) != 0 ? FixupMode.SegmentRelative : FixupMode.SelfRelative;
fixup.Location = (FixupLocation)((w >> 10) & 0x0F);
fixup.DataOffset = (UInt16)(w & 0x03FF);
byte b = reader.ReadByte();
bool useFrameThread = (b & 0x80) != 0;
if (useFrameThread)
{
int frameNumber = (b >> 4) & 0x3;
FixupThreadDefinition thread = context.FrameThreads[frameNumber];
if (!thread.IsDefined)
{
throw new InvalidDataException("Frame thread " + frameNumber + " is not defined.");
}
FixupFrame spec = new FixupFrame();
spec.Method = (FixupFrameMethod)thread.Method;
spec.IndexOrFrame = thread.IndexOrFrame;
fixup.Frame = spec;
}
else
{
FixupFrame spec = new FixupFrame();
spec.Method = (FixupFrameMethod)((b >> 4) & 7);
if ((int)spec.Method <= 3)
{
spec.IndexOrFrame = reader.ReadIndex();
}
fixup.Frame = spec;
}
bool useTargetThread = (b & 0x08) != 0;
if (useTargetThread)
{
bool hasTargetDisplacement = (b & 0x04) != 0;
int targetNumber = b & 3;
FixupThreadDefinition thread = context.TargetThreads[targetNumber];
if (!thread.IsDefined)
{
throw new InvalidDataException("Target thread " + targetNumber + " is not defined.");
}
FixupTargetMethod method = (FixupTargetMethod)((int)thread.Method & 3);
if (hasTargetDisplacement)
{
method |= (FixupTargetMethod)4;
}
FixupTarget spec = new FixupTarget();
spec.Referent = ResolveFixupReferent(context, method, thread.IndexOrFrame);
if ((int)method <= 3)
{
spec.Displacement = reader.ReadUInt16Or32();
}
fixup.Target = spec;
}
else
{
FixupTargetMethod method = (FixupTargetMethod)(b & 7);
UInt16 indexOrFrame = reader.ReadIndex();
FixupTarget spec = new FixupTarget();
spec.Referent = ResolveFixupReferent(context, method, indexOrFrame);
if ((int)method <= 3)
{
spec.Displacement = reader.ReadUInt16Or32();
}
fixup.Target = spec;
}
return(fixup);
}
