/**************************** omf2asm.cpp *********************************
* Author: Agner Fog, modified by Don Clugston
* Date created: 2007-05-27
* Last modified: 2014-05-32
* Project: objconv
* Module: omf2asm.cpp
* Description:
* Module for disassembling OMF object files
*
* (c) 2007-2014 GNU General Public License www.gnu.org/copyleft/gpl.html
*****************************************************************************/
#include "stdafx.h"
// Constructor
COMF2ASM::COMF2ASM() {
}
// Convert
void COMF2ASM::Convert() {
// Do the conversion
// Tell disassembler
Disasm.Init(0, 0);
// Make temporary Segments table
CountSegments();
// Make external symbols in Disasm
MakeExternalSymbolsTable();
// Make public symbols in Disasm
MakePublicSymbolsTable();
// Make symbol table entries for communal symbols.
MakeCommunalSymbolsTable();
// Make Segment list and relocations list
MakeSegmentList();
// Make group definitions
MakeGroupDefinitions();
// Disassemble
Disasm.Go();
// Take over output file from Disasm
*this << Disasm.OutFile;
}
void COMF2ASM::CountSegments() {
// Make temporary Segments table
uint32 i; // Record number
uint32 NameIndex; // Name index
uint32 ClassIndex; // Class name index
SOMFSegment SegRecord; // Segment record
// Define structure of attributes
OMF_SAttrib Attributes;
// Initialize temporary list of segments. Entry 0 is blank
Segments.PushZero();
// Search for SEGDEF records
for (i = 0; i < NumRecords; i++) {
if (Records[i].Type2 == OMF_SEGDEF) {
// SEGDEF record
Records[i].Index = 3;
// Loop through entries in record. There should be only 1
while (Records[i].Index < Records[i].End) {
// Read segment attributes
Attributes.b = Records[i].GetByte();
if (Attributes.u.A == 0) {
// Frame and Offset only included if A = 0
Records[i].GetWord(); // Frame ignored
SegRecord.Offset = Records[i].GetByte();
}
else SegRecord.Offset = 0;
SegRecord.Size = Records[i].GetNumeric();
NameIndex = Records[i].GetIndex();
ClassIndex = Records[i].GetIndex(); // Class index
Records[i].GetIndex(); // Overlay index ignored
SegRecord.NameO = GetLocalNameO(NameIndex); // Segment name
if (Attributes.u.B) {
// Segment is big
if (Attributes.u.P) {
// 32 bit segment. Big means 2^32 bytes!
err.submit(2306);
}
else {
// 16 bit segment. Big means 2^16 bytes
SegRecord.Size = 0x10000;
}
}
// Get word size
SegRecord.WordSize = Attributes.u.P ? 32 : 16;
// Get alignment
switch (Attributes.u.A) {
case 0: // Absolute segment
case 1: // Byte alignment
SegRecord.Align = 0;
break;
case 2: // Word alignment
SegRecord.Align = 1;
break;
case 3: // Paragraph alignment
SegRecord.Align = 4;
break;
case 4: // Page alignment
SegRecord.Align = 16;
break;
case 5: // DWord alignment
SegRecord.Align = 2;
break;
default: // Unknown
SegRecord.Align = 3; // Arbitrary value
break;
}
// Get further attributes from class name
char * ClassName = GetLocalName(ClassIndex);
// Convert class name to upper case
uint32 n = (uint32)strlen(ClassName);
for (uint32 j = 0; j < n; j++) ClassName[j] &= ~0x20;
// Search for known class names.
// Standard names are CODE, DATA, BSS, CONST, STACK
if (strstr(ClassName, "CODE") || strstr(ClassName, "TEXT")) {
// Code segment
SegRecord.Type = 1;
}
else if (strstr(ClassName, "DATA")) {
// Data segment
SegRecord.Type = 2;
}
else if (strstr(ClassName, "BSS")) {
// Unitialized data segment
SegRecord.Type = 3;
}
else if (strstr(ClassName, "CONST")) {
// Constant data segment
SegRecord.Type = 4;
}
else if (strstr(ClassName, "STACK")) {
// Stack segment.
SegRecord.Type = 0;
}
else {
// Unknown/user defined class. Assume data segment
SegRecord.Type = 2;
}
// Store temporary segment record
Segments.Push(SegRecord);
}
if (Records[i].Index != Records[i].End) err.submit(1203); // Check for consistency
}
}
FirstComDatSection = Segments.GetNumEntries();
// Communal sections (as used by Digital Mars):
// This part by Don Clugston
for (i = 0; i < NumRecords; i++) {
if (Records[i].Type2 == OMF_COMDAT) {
Records[i].Index = 3;
uint8 flags = Records[i].GetByte();
if ((flags & 2) != 0) {
// don't support iterated data yet
err.submit(2318); // Error message: not supported
continue;
}
uint8 attribs = Records[i].GetByte();
uint8 align = Records[i].GetByte();
uint32 ofs = Records[i].GetNumeric();
Records[i].GetIndex(); // type (ignore)
//uint16 publicBase = 0;
uint16 publicSegment = 0;
// From the OMF Spec 1.1: "If alloc type is EXPLICIT, public base is present and is
// identical to public base fields BaseGroup, Base Segment & BaseFrame in the PUBDEF."
// BUT: In the diagram in the spec it is described as 1-2 bytes (ie, an Index field).
// but in PUBDEF, those fields are Index, Index, or Index, zero, Index. (2-5 bytes)
// The diagram appears to be erroneous.
if ((attribs & 0xF) == 0){
//publicBase = Records[i].GetIndex();
publicSegment = Records[i].GetIndex();
if (publicSegment == 0) {
//Records[i].GetIndex(); // skip frame in this case
// I don't have the Digital Mars obj spec, but this seems to help ??
publicSegment = Records[i].GetIndex(); // ??
}
}
uint16 publicName = Records[i].GetIndex();
uint32 RecSize = Records[i].End - Records[i].Index; // Calculate size of data
if (attribs & 0xF) {
SegRecord.Type = 0x1000 | (attribs & 0xFF);
SegRecord.WordSize = (attribs & 0x2) ? 32 : 16;
}
else {
// use value from segdef
SegRecord.Type = 0x1000 | Segments[publicSegment].Type;
SegRecord.WordSize = Segments[publicSegment].WordSize;
}
//SegRecord.Type |= 1;//!!
if (align != 0) {
// alignment: (none), byte, word, paragraph, page, dword, arbitrary, arbitrary.
static const int alignvalues[] = {0, 0, 1, 4, 16, 2, 3, 3};
SegRecord.Align = alignvalues[align & 0x7];
}
else { // use value from segdef
SegRecord.Align = Segments[publicSegment].Align;
}
SegRecord.Size = RecSize;
// Get function name
const char * name = GetLocalName(publicName);
// Make a section name by putting _text$ before function name
uint32 ComdatSectionNameIndex = NameBuffer.Push("_text$", 6);
NameBuffer.PushString(name); // append function name
SegRecord.NameO = ComdatSectionNameIndex;
SegRecord.NameIndex = publicName;
if (flags & 1) {
// continuation.
// Add to the length to the previous entry.
Segments[Segments.GetNumEntries()-1].Size += RecSize;
}
else {
SegRecord.Offset = ofs;
Segments.Push(SegRecord);
}
}
}
// Communal sections (as used by Borland):
for (i = 0; i < NumRecords; i++) {
if (Records[i].Type2 == OMF_COMDEF) {
uint32 DType, DSize = 0, DNum;
uint16 Segment = 0;
const char * FuncName = 0;
// Loop through possibly multiple entries in record
while (Records[i].Index < Records[i].End) {
// Get function name
FuncName = Records[i].GetString();
Records[i].GetByte(); // Type index, should be 0, ignored
DType = Records[i].GetByte(); // Data type
switch (DType) {
case 0x61:
DNum = Records[i].GetLength();
DSize = Records[i].GetLength() * DNum;
break;
case 0x62:
DSize = Records[i].GetLength();
break;
default:
DSize = Records[i].GetLength();
if (DType < 0x60) { // Borland segment index
Segment = DType;
break;
}
err.submit(2016); // unknown type
break;
}
}
if (Segment >= Segments.GetNumEntries()) {err.submit(2016); return;}
// Copy segment record
SegRecord = Segments[Segment];
// Make a section name as SEGMENTNAME$FUNCTIONNAME
const char * SegmentName = NameBuffer.Buf() + SegRecord.NameO;
uint32 ComdatSectionNameIndex = NameBuffer.Push(SegmentName, strlen(SegmentName));
NameBuffer.Push("$", 1);
NameBuffer.PushString(FuncName); // append function name
SegRecord.NameO = ComdatSectionNameIndex;
SegRecord.Size = DSize;
SegRecord.Type |= 0x1000;
//SegRecord.BufOffset = ??
// Store segment
Segments.Push(SegRecord);
if (Records[i].Index != Records[i].End) err.submit(1203); // Check for consistency
}
}
// Number of segments, not including blank zero entry
NumSegments = Segments.GetNumEntries() - 1;
}
void COMF2ASM::MakeExternalSymbolsTable() {
// Make symbol table and string table entries for external symbols
uint32 iextsym; // External symbol index
uint32 isymo; // Symbol index in disassembler
uint32 NumExtSym = SymbolNameOffset.GetNumEntries(); // Number of external symbols
ExtdefTranslation.SetNum(NumExtSym+1); // Allocate space in symbol index translation table
// Loop through external symbol names
for (iextsym = 1; iextsym < NumExtSym; iextsym++) {
// Get name
const char * Name = GetSymbolName(iextsym);
// Define symbol
isymo = Disasm.AddSymbol(0, 0, 0, 0, 0x20, 0, Name);
// Update table for translating old EXTDEF number to disassembler symbol index
ExtdefTranslation[iextsym] = isymo;
}
}
void COMF2ASM::MakePublicSymbolsTable() {
// Make symbol table entries for public symbols
uint32 i; // Record index
char * string; // Symbol name
uint32 Segment; // Segment
uint32 Offset; // Offset
uint32 isymo; // Symbol number in disasm
uint32 CommunalSection = FirstComDatSection; // Index to communal section
PubdefTranslation.Push(0); // Make index 0 = 0
// Search for PUBDEF records
for (i = 0; i < NumRecords; i++) {
if (Records[i].Type2 == OMF_PUBDEF) {
// PUBDEF record
Records[i].Index = 3;
Records[i].GetIndex(); // Group. Ignore
Segment = Records[i].GetIndex(); // Segment
if (Segment == 0) Records[i].GetWord(); // Base frame. Ignore
// Loop through strings in record
while (Records[i].Index < Records[i].End) {
string = Records[i].GetString(); // Symbol name
Offset = Records[i].GetNumeric(); // Offset to segment
Records[i].GetIndex(); // Type index. Ignore
// Define symbol
isymo = Disasm.AddSymbol(Segment, Offset, 0, 0, 4, 0, string);
// Update table for translating old PUBDEF number to disassembler symbol index
PubdefTranslation.Push(isymo);
}
if (Records[i].Index != Records[i].End) err.submit(1203); // Check for consistency
}
}
// Search for OMF_COMDEF records
for (i = 0; i < NumRecords; i++) {
if (Records[i].Type2 == OMF_COMDEF) {
// COMDEF record, Borland communal name
uint32 DType;
//uint32 DSize;
//uint32 DNum;
Records[i].Index = 3;
// Loop through possibly multiple entries in record
while (Records[i].Index < Records[i].End) {
string = Records[i].GetString();
Records[i].GetByte(); // Type index, should be 0, ignore
DType = Records[i].GetByte(); // Data type
switch (DType) {
case 0x61:
//DNum = Records[i].GetLength();
//DSize = Records[i].GetLength();
continue; // Don't know what to do with this type. Ignore
case 0x62:
//DSize = Records[i].GetLength();
continue; // Don't know what to do with this type. Ignore
default:
//DSize = Records[i].GetLength();
if (DType < 0x60) { // Borland segment index
break;
}
continue; // Unknown type. Ignore
}
// Define symbol
Segment = CommunalSection;
isymo = Disasm.AddSymbol(Segment, 0, 0, 0, 0x10, 0, string);
// Update table for translating old PUBDEF number to disassembler symbol index
PubdefTranslation.Push(isymo);
}
CommunalSection++;
if (Records[i].Index != Records[i].End) err.submit(1203); // Check for consistency
}
}
}
void COMF2ASM::MakeCommunalSymbolsTable() {
// Make symbol table entries for communal symbols
char * string; // Symbol name
// Search for communal records
for (uint32 i = 0; i < NumRecords; i++) {
// Count communal records
if (Records[i].Type2 == OMF_CEXTDEF) {
Records[i].Index = 3;
// Loop through strings in record
while (Records[i].Index < Records[i].End) {
uint32 LIndex = Records[i].GetIndex();
Records[i].GetIndex(); // Group. Ignore
string = GetLocalName(LIndex);
// find section with same name
int32 section = 0;
for (uint32 j = 0; j < Segments.GetNumEntries(); j++) {
if (Segments[j].NameIndex == LIndex) {
section = (int32)j; break;
}
}
// Define symbol
Disasm.AddSymbol(section, 0, 0, 0, 0x10, 0, string);
}
}
}
}
void COMF2ASM::MakeGroupDefinitions() {
// Make segment group definitions
uint32 i; // Record index
// Search for group records
for (i = 0; i < NumRecords; i++) {
if (Records[i].Type2 == OMF_GRPDEF) {
// GRPDEF record
Records[i].Index = 3;
// Get group name
uint32 ClassIndex = Records[i].GetIndex();
char * GroupName = GetLocalName(ClassIndex);
// Define group
Disasm.AddSectionGroup(GroupName, 0);
// Loop through remaining entries in record
while (Records[i].Index < Records[i].End) {
// Entry type should be 0xFF
uint8 Type = Records[i].GetByte();
// Get member name
int32 NameIndex = Records[i].GetIndex();
// Check if type valid
if (Type == 0xFF && NameIndex > 0) {
// A group member is found. Add member to group
Disasm.AddSectionGroup(GroupName, NameIndex);
}
}
if (Records[i].Index != Records[i].End) err.submit(1203); // Check for consistency
}
}
}
// MakeSegmentList
void COMF2ASM::MakeSegmentList() {
// Make Sections list in Disasm
int32 SegNum; // Segment number
int32 Segment = 0; // Segment number in OMF record
uint32 RecNum; // OMF record number
uint32 LastDataRecord; // OMF record number of last LEDATA record
uint32 RecOffset; // Segment offset of LEDATA, LIDATA record
uint32 RecSize; // Data size of LEDATA, LIDATA record
uint32 LastDataRecordSize; // Last RecSize
uint32 LastOffset; // Last RecOffset
int8 * LastDataRecordPointer; // Point to last raw data
uint32 BufOffset; // Offset of segment into SegmentData buffer
CMemoryBuffer TempBuf; // Temporary buffer for building raw data
// Loop through segments
for (SegNum = 1; SegNum <= NumSegments; SegNum++) {
// Get size
uint32 SegmentSize = Segments[SegNum].Size;
if (SegmentSize == 0) continue; // Empty segment
// Allocate temporary data buffer and reset it
TempBuf.SetSize(SegmentSize + 16);
int FillByte = 0; // Byte to fill memory with
if (Segments[SegNum].Type == 1) {
// Code segment. Fill any unused bytes with NOP opcode = 0x90
FillByte = 0x90;
}
memset(TempBuf.Buf(), FillByte, SegmentSize + 16);// Reset to all 0 or NOP
LastDataRecord = 0;
LastDataRecordSize = 0;
LastDataRecordPointer = 0;
LastOffset = 0;
int comdatsSoFar = 0;
// Search for LEDATA, LIDATA and FIXUPP records for this segment
for (RecNum = 0; RecNum < NumRecords; RecNum++) {
if (Records[RecNum].Type2 == OMF_LEDATA) {
// LEDATA record
Records[RecNum].Index = 3; // Initialize record reading
Segment = Records[RecNum].GetIndex();// Read segment number
if ((Segment & 0xC000) == 0x4000) {
// Refers to Borland communal section
Segment = (Segment & ~0x4000) + FirstComDatSection - 1;
}
if (Segment != SegNum) continue; // Does not refer to this segment
RecOffset = Records[RecNum].GetNumeric();// Read offset of this record
RecSize = Records[RecNum].End - Records[RecNum].Index; // Calculate size of data
LastDataRecord = RecNum; // Save for later FIXUPP that refers to this record
if (RecOffset < LastOffset + LastDataRecordSize && LastOffset < RecOffset + RecSize) {
// Overlapping data records
if (RecOffset + 8 < LastOffset + LastDataRecordSize || Segments[SegNum].Type != 1) {
// Overlapping data by more than 7 bytes or not executable code
err.submit(1207);
}
else {
// Possibly backpatched code
err.submit(1208); // Warning
err.ClearError(1208); // Report only once
}
}
LastDataRecordSize = RecSize;
LastDataRecordPointer = Records[RecNum].buffer + Records[RecNum].FileOffset + Records[RecNum].Index;
LastOffset = RecOffset; // Save offset for subsequent FIXUPP records
// Check if data within segment
if (RecOffset + RecSize > SegmentSize) {
err.submit(2309, GetSegmentName(Segment));
continue;
}
// Put raw data into temporary buffer
memcpy(TempBuf.Buf() + RecOffset, LastDataRecordPointer, RecSize);
} // Finished with LEDATA record
if (Records[RecNum].Type2 == OMF_LIDATA) {
// LIDATA record
Records[RecNum].Index = 3; // Initialize record reading
Segment = Records[RecNum].GetIndex();
if (Segment != SegNum) continue; // Does not refer to this segment
LastDataRecord = RecNum; // Save for later FIXUPP that refers to this record
RecOffset = Records[RecNum].GetNumeric();// Read offset
if (RecOffset > SegmentSize) {
err.submit(2310); continue; // Error: outside bounds
}
// Unpack LIDATA blocks recursively
RecSize = Records[RecNum].UnpackLIDATABlock(TempBuf.Buf() + RecOffset, SegmentSize - RecOffset);
if (RecOffset < LastOffset + LastDataRecordSize && LastOffset < RecOffset + RecSize) {
// Overlapping data records
err.submit(1207); // Warning
}
LastDataRecordSize = RecSize; // Save data size
LastOffset = RecOffset; // Save offset for subsequent FIXUPP records
} // Finished with LIDATA record
if (Records[RecNum].Type2 == OMF_COMDAT) {
// COMDAT record.
Records[RecNum].Index = 3; // Initialize record reading
uint16 flags = Records[RecNum].GetByte();
if ((flags&1)==0) { // not a continuation
++comdatsSoFar;
LastDataRecord = RecNum; // Save for later FIXUPP that refers to this record
}
Segment = FirstComDatSection + comdatsSoFar-1;
if (SegNum != Segment) continue;
uint16 attribs = Records[RecNum].GetByte();
Records[RecNum].GetByte(); // align (ignore)
RecOffset = Records[RecNum].GetNumeric();
Records[RecNum].GetIndex(); // type (ignore)
if ((attribs&0xF)==0) {
Records[RecNum].GetIndex(); // public base
uint16 publicSegment = Records[RecNum].GetIndex();
if (publicSegment==0) Records[RecNum].GetIndex(); // public frame (ignore)
}
Records[RecNum].GetIndex(); // public name (ignore)
RecSize = Records[RecNum].End - Records[RecNum].Index; // Calculate size of data
LastDataRecord = RecNum; // Save for later FIXUPP that refers to this record
LastDataRecordSize = RecSize;
LastDataRecordPointer = Records[RecNum].buffer + Records[RecNum].Index+Records[RecNum].FileOffset;
LastOffset = RecOffset;
// Put raw data into temporary buffer
memcpy(TempBuf.Buf() + RecOffset, LastDataRecordPointer, RecSize);
} // Finished with COMDAT record
if (Records[RecNum].Type2 == OMF_FIXUPP) {
// FIXUPP record
if (Segment != SegNum) continue; // Does not refer to this segment
Records[RecNum].Index = 3;
if (Records[LastDataRecord].Type2 == OMF_LEDATA) {
// FIXUPP for last LEDATA record
// Make relocation records
MakeRelocations(Segment, RecNum, LastOffset, LastDataRecordSize, (uint8*)TempBuf.Buf());
}
else if (Records[RecNum].Index < Records[RecNum].End) {
// Non-empty FIXUPP record does not refer to LEDATA record
if (Records[LastDataRecord].Type2 == OMF_COMDAT) {
// FIXUPP for last COMDAT record
// Make relocation records
MakeRelocations(Segment, RecNum, LastOffset, LastDataRecordSize, (uint8*)TempBuf.Buf());
}
else if (Records[LastDataRecord].Type2 == OMF_LIDATA) {
err.submit(2311); // Error: Relocation of iterated data not supported
}
else {
err.submit(2312); // Does not refer to data record
}
}
}
} // End of loop to search for LEDATA, LIDATA and FIXUPP records for this segment
// Transfer raw data from TempBuf to SegmentData buffer
BufOffset = SegmentData.Push(TempBuf.Buf(), SegmentSize);
// Remember offset into SegmentData
Segments[SegNum].BufOffset = BufOffset;
} // End of first loop through segments
// We must put all segments into SegmentData buffer before we assign pointers to
// the raw data because otherwise the SegmentData buffer might me reallocated
// when it grows and the pointers become invalid. This is the reasons why we
// have two loops through the segments here.
// Second loop through segments
int totalcodesize=0;
for (SegNum = 1; SegNum <= NumSegments; SegNum++) {
// Pointer to merged raw data
uint8 * RawDatap = (uint8*)SegmentData.Buf() + Segments[SegNum].BufOffset;
// Size of raw data
uint32 InitSize = (Segments[SegNum].Type == 3) ? 0 : Segments[SegNum].Size;
// Define segment
const char * SegmentName = NameBuffer.Buf() + Segments[SegNum].NameO;
Disasm.AddSection(RawDatap, InitSize, Segments[SegNum].Size, Segments[SegNum].Offset,
Segments[SegNum].Type, Segments[SegNum].Align, Segments[SegNum].WordSize, SegmentName);
if (Segments[SegNum].Type == 1 || Segments[SegNum].Type == 0x1001) {
totalcodesize += Segments[SegNum].Size;
}
}
}
// MakeRelocations
void COMF2ASM::MakeRelocations(int32 Segment, uint32 RecNum, uint32 SOffset, uint32 RSize, uint8 * SData) {
// Make relocations for object and executable files
// Parameters:
// Segment = segment index of last LEDATA record
// RecNum = FIXUPP record number
// SOffset = segment relative offset of last LEDATA record
// RSize = Size of last LEDATA record
// SData = pointer to raw segment data
uint32 Frame, Target, TargetDisplacement; // Contents of FIXUPP record
uint8 byte1, byte2; // First two bytes of subrecord
int32 Inline; // Inline address or addend in relocation source
//int16 InlineSeg; // Segment address stored in relocation source
int32 Addend; // Correction to add to target address
int32 SourceSize; // Size of relocation source
uint32 RelType; // Relocation type, as defined in disasm.h
int32 TargetSegment; // Target segment or group
uint32 TargetOffset; // Target offset
uint32 TargetSymbol; // Symbol index of target
uint32 ReferenceIndex; // Segment/group index of reference frame
// Bitfields in subrecords
OMF_SLocat Locat; // Structure of first two bytes of FIXUP subrecord swapped = Locat field
OMF_SFixData FixData; // Structure of FixData field in FIXUP subrecord of FIXUPP record
OMF_STrdDat TrdDat; // Structure of Thread Data field in THREAD subrecord of FIXUPP record
Records[RecNum].Index = 3;
// Loop through entries in record
while (Records[RecNum].Index < Records[RecNum].End) {
// Read first byte
byte1 = Records[RecNum].GetByte();
if (byte1 & 0x80) {
// This is a FIXUP subrecord
Frame = 0; Target = 0; TargetDisplacement = 0; Addend = 0; ReferenceIndex = 0;
// read second byte
byte2 = Records[RecNum].GetByte();
// swap bytes and put into byte12 bitfield
Locat.bytes[1] = byte1;
Locat.bytes[0] = byte2;
// Read FixData
FixData.b = Records[RecNum].GetByte();
// Read conditional fields
if (FixData.s.F) {
// Frame specified by previously define thread
// Does anybody still use compression of repeated fixup targets?
// I don't care to support this if it is never used
err.submit(2313); // Error message: not supported
continue;
}
else {
if (FixData.s.Frame < 4) {
// Frame datum field present
Frame = Records[RecNum].GetIndex();
}
else Frame = 0;
switch (FixData.s.Frame) { // Frame method
case 0: // F0: segment
ReferenceIndex = Frame;
break;
case 1: // F1: group
// Groups defined after segments. Add number of segments to get group index
ReferenceIndex = Frame + NumSegments;
break;
default:
case 2: // F2: external symbol
ReferenceIndex = 0;
break;
case 4: // F4: traget frame = source frame
Frame = Segment;
break;
case 5: // F5: target frame = target segment
Frame = 0;
break;
}
}
if (FixData.s.T == 0) {
// Target specified
Target = Records[RecNum].GetIndex();
if ((Target & 0xC000) == 0x4000) {
// Refers to Borland communal section
Target = (Target & ~0x4000) + FirstComDatSection - 1;
}
//uint32 TargetMethod = FixData.s.Target + FixData.s.P * 4;
}
else {
// Target specified in previous thread
// Does anybody still use compression of repeated fixup targets?
// I don't care to support this if it is never used
err.submit(2313); // Error message: not supported
continue;
}
if (FixData.s.P == 0) {
TargetDisplacement = Records[RecNum].GetNumeric();
}
if (!SData || Locat.s.Offset > RSize) {
err.submit(2032); // Relocation points outside segment
return;
}
// Get inline addend and check relocation method
// Pointer to relocation source inline in raw data:
uint8 * inlinep = SData + SOffset + Locat.s.Offset;
Inline = 0; SourceSize = 0;
//InlineSeg = 0;
TargetSegment = 0; TargetOffset = 0; TargetSymbol = 0;
// Relocation type
if (Locat.s.M) {
// Segment relative
RelType = 8;
}
else {
// (E)IP relative
RelType = 2;
}
switch (Locat.s.Location) {// Relocation method
case OMF_Fixup_8bit: // 8 bit
SourceSize = 1;
Inline = *(int8*)inlinep;
break;
case OMF_Fixup_16bit: // 16 bit
SourceSize = 2;
Inline = *(int16*)inlinep;
break;
case OMF_Fixup_32bit: // 32 bit
SourceSize = 4;
Inline = *(int32*)inlinep;
break;
case OMF_Fixup_Far: // far 16+16 bit
RelType = 0x400;
SourceSize = 4;
Inline = *(int16*)inlinep;
break;
case OMF_Fixup_Farword: // far 32+16 bit
case OMF_Fixup_Pharlab48:
RelType = 0x400;
SourceSize = 6;
Inline = *(int32*)inlinep;
break;
case OMF_Fixup_Segment: // segment selector
if (TargetDisplacement || FixData.s.Target == 2) {
// An offset is specified or an external symbol.
// Segment of symbol is required (seg xxx)
RelType = 0x200;
}
else {
// A segment name or group name is required
RelType = 0x100;
};
SourceSize = 2;
Inline = *(int16*)inlinep;
break;
case OMF_Fixup_16bitLoader: // 16-bit loader resolved
RelType = 0x21;
SourceSize = 2;
Inline = *(int16*)inlinep;
break;
case OMF_Fixup_32bitLoader: // 32-bit loader resolved
RelType = 0x21;
SourceSize = 4;
Inline = *(int32*)inlinep;
break;
default: // unknown or not supported
RelType = 0;
SourceSize = 0;
Inline = 0;
} // end switch
// Offset of relocation source
uint32 SourceOffset = SOffset + Locat.s.Offset;
// Relocation type: direct or (E)IP-relative
if (RelType == 2) {
// (E)IP-relative
// Correct for difference between source address and end of instruction
Addend = -SourceSize;
}
// Check target method
switch (FixData.s.Target) { // = Target method modulo 4
case 0: // T0 and T4: Target = segment
// Local or public symbol
TargetSegment = Target; // Target segment
TargetOffset = TargetDisplacement; // Target offset
if (RelType != 0x100) {
// Add inline to target address, except if target is a segment only
TargetOffset += Inline;
Addend -= Inline; // Avoid adding Inline twice
}
break;
case 1: // T1 and T5: Target = segment group
// Warning: this method has not occurred. Not tested!
// Groups are numbered in sequence after segments in Disasm. Add number of segments to group index
TargetSegment = Target + NumSegments;// Target group
TargetOffset = TargetDisplacement; // Target offset
if (RelType != 0x100) {
// Add inline to target address, except if target is a segment only
TargetOffset += Inline;
Addend -= Inline; // Avoid adding Inline twice
}
break;
case 2: // T2 and T6: Target = external symbol
// Translate old EXTDEF index to new symbol table index
if (Target < ExtdefTranslation.GetNumEntries()) {
TargetSymbol = ExtdefTranslation[Target];
}
break;
default: // Unknown method
err.submit(2314, FixData.s.Target + FixData.s.P * 4);
}
if (TargetSymbol == 0) {
// Make symbol record for target
TargetSymbol = Disasm.AddSymbol(TargetSegment, TargetOffset, 0, 0, 2, 0, 0);
}
if (FixData.s.Frame == 4 && FixData.s.Target + FixData.s.P*4 == 6) {
// Note:
// Frame method F4 is apparently used by 16-bit Borland compiler for
// indicating floating point instructions that can be emulated if no
// 8087 processor is present. I can't find this documented anywhere.
// I don't know what the exact criterion is for indicating that a FIXUP
// subrecord is not a relocation record but a f.p. emulating record.
// I have chosen to consider all subrecords with frame method F4 and
// target method T6 to be ignored.
;
}
else {
// This is a proper relocation subrecord
Disasm.AddRelocation(Segment, SourceOffset, Addend, RelType, SourceSize, TargetSymbol, ReferenceIndex);
}
}
else {
// This is a THREAD subrecord.
// I don't think this feature for compressing fixup data is
// used any more, if it ever was. I am not supporting it here.
// Frame threads can be safely ignored. A target thread cannot
// be ignored if there is any reference to it. The error is
// reported above at the reference to a target thread, not here.
TrdDat.b = byte1; // Put byte into bitfield
if (TrdDat.s.Method < 4) { // Make sure we read this correctly, even if ignored
Records[RecNum].GetIndex(); // has index field if method < 4 ?
}
}
} // Finished loop through subrecords
if (Records[RecNum].Index != Records[RecNum].End) err.submit(1203); // Check for consistency
}