// Apply relocations to a segment.
bool ApplyRelocations(ImageReader rdr, int cRelocations, NeSegment seg)
{
string module = "";
Address address = null;
NeRelocationEntry rep = null;
for (int i = 0; i < cRelocations; i++)
{
rep = new NeRelocationEntry
{
address_type = rdr.ReadByte(),
relocation_type = rdr.ReadByte(),
offset = rdr.ReadLeUInt16(),
target1 = rdr.ReadLeUInt16(),
target2 = rdr.ReadLeUInt16(),
};
// Get the target address corresponding to this entry.
// If additive, there is no target chain list. Instead, add source
// and target.
bool additive = (rep.relocation_type & NE_RELFLAG_ADDITIVE) != 0;
Tuple <Address, ImportReference> impRef;
uint lp;
switch (rep.relocation_type & 3)
{
case NE_RELTYPE_ORDINAL:
module = moduleNames[rep.target1 - 1];
// Synthesize an import
lp = ((uint)rep.target1 << 16) | rep.target2;
if (importStubs.TryGetValue(lp, out impRef))
{
address = impRef.Item1;
}
else
{
address = addrImportStubs;
importStubs.Add(lp, new Tuple <Address, ImportReference>(
address,
new OrdinalImportReference(address, module, rep.target2)));
addrImportStubs += 8;
}
break;
case NE_RELTYPE_NAME:
module = moduleNames[rep.target1 - 1];
uint offName = lfaNew + this.offImportedNamesTable + rep.target2;
var nameRdr = new LeImageReader(RawImage, offName);
byte fnNameLength = nameRdr.ReadByte();
var abFnName = nameRdr.ReadBytes(fnNameLength);
lp = ((uint)rep.target1 << 16) | rep.target2;
if (importStubs.TryGetValue(lp, out impRef))
{
address = impRef.Item1;
}
else
{
address = addrImportStubs;
string fnName = Encoding.ASCII.GetString(abFnName);
importStubs.Add(lp, new Tuple <Address, ImportReference>(
address,
new NamedImportReference(address, module, fnName)));
}
break;
case NE_RELTYPE_INTERNAL:
if ((rep.target1 & 0xff) == 0xff)
{
throw new NotImplementedException();
}
else
{
address = segments[rep.target1 - 1].Address + rep.target2;
}
Debug.Print("{0}: {1:X4}:{2:X4} {3}",
i + 1,
address.Selector.Value,
address.Selector.Value,
"");
break;
case NE_RELTYPE_OSFIXUP:
/* Relocation type 7:
*
* These appear to be used as fixups for the Windows
* floating point emulator. Let's just ignore them and
* try to use the hardware floating point. Linux should
* successfully emulate the coprocessor if it doesn't
* exist.
*/
/*
* TRACE("%d: TYPE %d, OFFSET %04x, TARGET %04x %04x %s\n",
* i + 1, rep->relocation_type, rep->offset,
* rep->target1, rep->target2,
* NE_GetRelocAddrName( rep->address_type, additive ) );
*/
continue;
}
ushort offset = rep.offset;
// Apparently, high bit of address_type is sometimes set;
// we ignore it for now.
if (rep.address_type > NE_RADDR_OFFSET32)
{
diags.Error(
string.Format(
"Module {0}: unknown relocation address type {1:X2}. Please report",
module, rep.address_type));
return(false);
}
if (additive)
{
var sp = seg.Address + offset;
Debug.Print(" {0:X4}:{0:X4}", offset, offset);
byte b;
ushort w;
switch (rep.address_type & 0x7f)
{
case NE_RADDR_LOWBYTE:
b = mem.ReadByte(sp);
mem.WriteByte(sp, (byte)(b + address.Offset));
break;
case NE_RADDR_OFFSET16:
w = mem.ReadLeUInt16(sp);
mem.WriteLeUInt16(sp, (ushort)(w + address.Offset));
break;
case NE_RADDR_POINTER32:
w = mem.ReadLeUInt16(sp);
mem.WriteLeUInt16(sp, (ushort)(w + address.Offset));
mem.WriteLeUInt16(sp + 2, address.Selector.Value);
break;
case NE_RADDR_SELECTOR:
// Borland creates additive records with offset zero. Strange, but OK.
w = mem.ReadLeUInt16(sp);
if (w != 0)
{
diags.Error(string.Format("Additive selector to {0:X4}. Please report.", w));
}
else
{
mem.WriteLeUInt16(sp, address.Selector.Value);
}
break;
default:
goto unknown;
}
}
else
{
// Non-additive fixup.
do
{
var sp = seg.Address + offset;
ushort next_offset = mem.ReadLeUInt16(sp);
Debug.Print(" {0:X4}:{0:X4}", offset, next_offset);
switch (rep.address_type & 0x7f)
{
case NE_RADDR_LOWBYTE:
mem.WriteByte(sp, (byte)address.Offset);
break;
case NE_RADDR_OFFSET16:
mem.WriteLeUInt16(sp, (ushort)address.Offset);
break;
case NE_RADDR_POINTER32:
mem.WriteLeUInt16(sp, (ushort)address.Offset);
mem.WriteLeUInt16(sp + 2, address.Selector.Value);
break;
case NE_RADDR_SELECTOR:
mem.WriteLeUInt16(sp, address.Selector.Value);
break;
default:
goto unknown;
}
if (next_offset == offset)
{
break; // avoid infinite loop
}
if (next_offset >= seg.Alloc)
{
break;
}
offset = next_offset;
} while (offset != 0xffff);
}
}
return(true);
unknown:
var svc = Services.RequireService <IDiagnosticsService>();
svc.Warn("{0}: unknown ADDR TYPE {1}, " +
"TYPE {2}, OFFSET {3:X4}, TARGET {4:X4} {5:X4}",
seg.Address.Selector, rep.address_type, rep.relocation_type,
rep.offset, rep.target1, rep.target2);
return(false);
}