/**************************** cof2omf.cpp ********************************
* Author: Agner Fog
* Date created: 2007-02-03
* Last modified: 2007-02-03
* Project: objconv
* Module: cof2omf.cpp
* Description:
* Module for converting 32 bit PE/COFF file to OMF file
*
* Copyright 2007-2008 GNU General Public License http://www.gnu.org/licenses
*****************************************************************************/
#include "stdafx.h"
CCOF2OMF::CCOF2OMF () {
// Constructor
memset(this, 0, sizeof(*this));
}
void CCOF2OMF::Convert() {
// Do the conversion
if (WordSize != 32) {
err.submit(2317, WordSize); // Wrong word size
return;
}
// Allocate variable size buffers
SectionBuffer.SetNum(NSections + 2); // Allocate buffer for section translation list
SectionBuffer.SetZero(); // Initialize
SymbolBuffer.SetNum(NumberOfSymbols + 1); // Allocate buffer for symbol translation list
SymbolBuffer.SetZero(); // Initialize
NameBuffer.Push(0, 1); // Make first entry in NameBuffer empty
// Call the subfunctions
ToFile.SetFileType(FILETYPE_OMF); // Set type of output file
MakeSegmentList(); // Make temporary segment conversion list
MakeSymbolList(); // Make temporary symbol conversion list
MakeRelocationsList(); // Make temporary list of relocations (fixups) and sort it
MakeLNAMES(); // Make THEADR and LNAMES records
MakeSEGDEF(); // Make SEGDEF and GRPDEF records
MakeEXTDEF(); // Make EXTDEF records
MakePUBDEF(); // Make PUBDEF records
MakeLEDATA(); // Make LEDATA, LIDATA and FIXUPP records
MakeMODEND(); // Finish output file
*this << ToFile; // Take over new file buffer containing the converted file
}
void CCOF2OMF::MakeSegmentList() {
// Make temporary segment conversion list
const char * oldname; // Old name of section
uint32 namei; // Name index into NameBuffer
uint32 align; // Segment alignment = 2^align
int32 align2; // align2 = 2^align
uint32 flags; // Old flags
int i, j; // Loop counters
int oldsec; // Old section number
// Loop through old sections
for (j = 0; j < NSections; j++) {
// Old section number
oldsec = j + 1;
// Get old section header
SCOFF_SectionHeader * pSectionHeader = &SectionHeaders[j];
// Get name
oldname = GetSectionName(pSectionHeader->Name);
// Check for debug sections
if (strnicmp(oldname,"debug",5) == 0 || strnicmp(oldname+1,"debug",5) == 0) {
// This is a debug section
if (cmd.DebugInfo == CMDL_DEBUG_STRIP) {
// Remove debug info
SectionBuffer[oldsec].NewNumber = 0;
cmd.CountDebugRemoved();
continue;
}
else if (cmd.InputType != cmd.OutputType) {
err.submit(1029); // Warn that debug information is incompatible
}
}
// Check for directive sections
if (strnicmp(oldname,".drectve",8) == 0 || (pSectionHeader->Flags & (PE_SCN_LNK_INFO | PE_SCN_LNK_REMOVE))) {
// This is a directive section
if (cmd.ExeptionInfo) {
// Remove directive section
SectionBuffer[oldsec].NewNumber = 0;
cmd.CountExceptionRemoved();
continue;
}
}
// Get alignment
align = (pSectionHeader->Flags & PE_SCN_ALIGN_MASK) / PE_SCN_ALIGN_1;
if (align > 0) align--; // Alignment = 2^align
align2 = 1 << align; // 2^align
// Check for previous sections with same name
for (i = 0; i < SectionBufferNum; i++) {
if (strcmp(oldname, NameBuffer.Buf() + SectionBuffer[i].OldName) == 0) break; // Found same name
}
if (i < SectionBufferNum) {
// Previous section with same name found.
// i = first section with this name, oldsec = current section with this name
SectionBuffer[oldsec] = SectionBuffer[i]; // Copy record
SectionBuffer[oldsec].NewNameI = 0; // Indicate this is not the first record
// Check if alignment is the same
if (align != SectionBuffer[i].Align) {
err.submit(1060, oldname); // Warning different alignments
if (align > SectionBuffer[i].Align) SectionBuffer[i].Align = align; // Use highest alignment
}
// Get section header
SectionBuffer[oldsec].psechdr = pSectionHeader;
// Get size of this section
SectionBuffer[oldsec].Size = pSectionHeader->SizeOfRawData;
// Get offset relative to first section with same name
SectionBuffer[oldsec].Offset = SectionBuffer[i].Offset + SectionBuffer[i].SegmentSize;
// Align this section (We are aligning each section in the segment)
SectionBuffer[oldsec].Offset = (SectionBuffer[oldsec].Offset + align2 - 1) & (- align2);
// Update total size of all sections with same name
SectionBuffer[i].SegmentSize = SectionBuffer[oldsec].Offset + SectionBuffer[oldsec].Size;
}
else {
// No previous section found with same name. Make SOMFSegmentList record
SectionBufferNum = oldsec + 1; // End of entries in SectionBuffer
// Assign a number to this segment
SectionBuffer[oldsec].NewNumber = ++NumSegments;
SectionBuffer[oldsec].NewNameI = NumSegments + OMF_LNAME_LAST;
// Point to old section header
SectionBuffer[oldsec].psechdr = pSectionHeader;
// Give it a name
namei = NameBuffer.PushString(oldname); // Save name in buffer, because it is volatile
SectionBuffer[oldsec].OldName = namei; // Index to name
// Segment names like .text and _TEXT are both common. No need to convert the name
// Only restriction is length < 256.
// Do we need a unique segment name if the alignment is different from segments
// with same name in another module?
if (strlen(oldname) > 255) {
// Segment name too long. This is very unlikely
namei = NameBuffer.Push(oldname, 255); // Make truncated name
NameBuffer.Push(0, 1); // Terminate by zero
}
SectionBuffer[oldsec].NewName = namei; // Index to name
// Size
SectionBuffer[oldsec].Size = pSectionHeader->SizeOfRawData;
SectionBuffer[oldsec].SegmentSize = pSectionHeader->SizeOfRawData;
SectionBuffer[oldsec].Offset = 0;
// Alignment
SectionBuffer[oldsec].Align = align;
// Segment type
flags = pSectionHeader->Flags;
// Get segment class
if (flags & (PE_SCN_CNT_CODE | PE_SCN_MEM_EXECUTE)) {
// Code segment
SectionBuffer[oldsec].Class = OMF_LNAME_CODE;
}
else if (flags & PE_SCN_CNT_UNINIT_DATA) {
// Uninitialized data
SectionBuffer[oldsec].Class = OMF_LNAME_BSS;
}
else if (!(flags & PE_SCN_MEM_WRITE)) {
// Read only
SectionBuffer[oldsec].Class = OMF_LNAME_CONST;
}
else {
// Normal data
SectionBuffer[oldsec].Class = OMF_LNAME_DATA;
}
}
}
// Add 1 to section count because new section numbers are 1-based
SectionBufferNum = NSections + 1;
}
void CCOF2OMF::MakeSymbolList() {
// Make temporary symbol conversion list
int isym = 0; // current symbol table entry
//int jsym = 0; // auxiliary entry number
union { // Pointer to symbol table
SCOFF_SymTableEntry * p; // Normal pointer
int8 * b; // Used for address calculation
} Symtab;
Symtab.p = SymbolTable; // Set pointer to begin of SymbolTable
// Loop through symbol table
while (isym < NumberOfSymbols) {
// Check scope
if (Symtab.p->s.StorageClass == COFF_CLASS_EXTERNAL) {
// Scope is public or external
if (Symtab.p->s.SectionNumber > 0) {
// Symbol is public
SymbolBuffer[isym].Scope = S_PUBLIC; // Scope = public
SymbolBuffer[isym].NewIndex = ++NumPublicSymbols; // Public symbol number
// Get name
SymbolBuffer[isym].Name = NameBuffer.PushString(GetSymbolName(Symtab.p->s.Name));
// Find section in SectionBuffer
uint32 OldSection = Symtab.p->s.SectionNumber;
SymbolBuffer[isym].Segment = SectionBuffer[OldSection].NewNumber; // New segment number
// Calculate offset = offset into old section + offset of old section to first section with same name
SymbolBuffer[isym].Offset = Symtab.p->s.Value + SectionBuffer[OldSection].Offset;
}
else if (Symtab.p->s.SectionNumber == 0) {
// Symbol is external
SymbolBuffer[isym].Scope = S_EXTERNAL; // Scope = external
SymbolBuffer[isym].NewIndex = ++NumExternalSymbols; // External symbol number
SymbolBuffer[isym].Name = NameBuffer.PushString(GetSymbolName(Symtab.p->s.Name));
}
else if (Symtab.p->s.SectionNumber == COFF_SECTION_ABSOLUTE) {
// Symbol is public, absolute
SymbolBuffer[isym].Scope = S_PUBLIC; // Scope = public
SymbolBuffer[isym].NewIndex = ++NumPublicSymbols; // Public symbol number
// Get name
SymbolBuffer[isym].Name = NameBuffer.PushString(GetSymbolName(Symtab.p->s.Name));
SymbolBuffer[isym].Segment = 0; // 0 indicates absolute
SymbolBuffer[isym].Offset = Symtab.p->s.Value; // Store value in Offset
}
else {
// COFF_SECTION_DEBUG, COFF_SECTION_N_TV, COFF_SECTION_P_TV
// Ignore
}
}
// Skip auxiliary symbol table entries and increment pointer
isym += Symtab.p->s.NumAuxSymbols + 1;
Symtab.b += (Symtab.p->s.NumAuxSymbols + 1) * SIZE_SCOFF_SymTableEntry;
}
}
void CCOF2OMF::MakeRelocationsList() {
// Make temporary list of relocations (fixups) and sort it
uint32 i; // Relocation number in old file
int j; // Section number of relocation source in old file
int isym; // Symbol table index in old file
//int32 * paddend = 0; // Pointer to inline addend
uint32 TargetOldSection; // Section number of relocation target in old file
SOMFRelocation NewRel; // Entry in RelocationBuffer
union { // Pointer to symbol table
SCOFF_SymTableEntry * p; // Normal pointer
int8 * b; // Used for address calculation
} Symtab;
union { // Pointer to relocation entry
SCOFF_Relocation * p; // pointer to record
int8 * b; // used for address calculation and incrementing
} Reloc;
// Loop through section headers of old file
for (j = 0; j < NSections; j++) {
SCOFF_SectionHeader * SectionHeaderp = &SectionHeaders[j];
// Pointer to first relocation entry in section
Reloc.b = Buf() + SectionHeaderp->PRelocations;
// Loop through relocations in section
for (i = 0; i < SectionHeaderp->NRelocations; i++) {
// Find symbol table entry
isym = Reloc.p->SymbolTableIndex;
if ((uint32)isym >= (uint32)NumberOfSymbols) {
err.submit(2040); // SymbolTableIndex points outside Symbol Table
isym = 0;
}
Symtab.p = SymbolTable; // Set pointer to begin of SymbolTable
Symtab.b += SIZE_SCOFF_SymTableEntry * isym; // Calculate address of entry isym
// Find inline addend
if (Reloc.p->Type < COFF32_RELOC_SEG12) {
//paddend = (int32*)(Buf()+SectionHeaderp->PRawData+Reloc.p->VirtualAddress);
}
//else paddend = 0;
// Make entry in RelocationBuffer
// Relocation type
switch (Reloc.p->Type) {
case COFF32_RELOC_DIR32: // Direct 32 bit
NewRel.Mode = 1; break; // 0 = EIP-relative, 1 = direct
case COFF32_RELOC_REL32: // 32 bit EIP relative
NewRel.Mode = 0; break; // 0 = EIP-relative, 1 = direct
case COFF32_RELOC_ABS: // Ignore
continue;
default: // Other. Not supported
NewRel.Mode = -1; // -1 = unsupported.
// Postpone error message in case it refers to a debug section that is being removed
NewRel.TargetOffset = Reloc.p->Type; // Remember relocation type
//err.submit(2030, Reloc.p->Type); continue; // Unsupported relocation type
break;
}
// Get source
NewRel.Section = j + 1; // Section number in old file
NewRel.SourceOffset = Reloc.p->VirtualAddress;// Offset of source relative to section
// Get target
if (Symtab.p->s.SectionNumber > 0) {
// Local
NewRel.Scope = S_LOCAL; // 0 = local, 2 = external
TargetOldSection = Symtab.p->s.SectionNumber; // Target section
if (TargetOldSection > uint32(NSections)) {
// SectionNumber out of range
err.submit(2035); continue;
}
// Segment index of target in new file:
NewRel.TargetSegment = SectionBuffer[TargetOldSection].NewNumber;
// Offset relative to old section
NewRel.TargetOffset = Symtab.p->s.Value;
// Add offset relative to first section with same name to get offset relative to new segment
NewRel.TargetOffset += SectionBuffer[TargetOldSection].Offset;
}
else {
// External
NewRel.Scope = S_EXTERNAL; // 0 = local, 2 = external
NewRel.TargetOffset = 0; // Any addend is inline
// Find EXTDEF index in SymbolBuffer
NewRel.TargetSegment = SymbolBuffer[isym].NewIndex;
}
// Put NewRel into RelocationBuffer
RelocationBuffer.Push(NewRel);
// Increment pointer to relocation record
Reloc.b += SIZE_SCOFF_Relocation; // Next relocation record
}
}
// Sort RelocationBuffer
RelocationBuffer.Sort();
// Store number of relocations
NumRelocations = RelocationBuffer.GetNumEntries();
// Check for overlapping relocation sources
for (uint32 i = 1; i < RelocationBuffer.GetNumEntries(); i++) {
if (RelocationBuffer[i].Section == RelocationBuffer[i-1].Section
&& RelocationBuffer[i].SourceOffset >= RelocationBuffer[i-1].SourceOffset
&& RelocationBuffer[i].SourceOffset < RelocationBuffer[i-1].SourceOffset + 4
&& (RelocationBuffer[i].Mode == 0 || RelocationBuffer[i].Mode == 1)) {
err.submit(2210); // Error: overlapping relocation sources
}
}
}
void CCOF2OMF::MakeLNAMES() {
// Make THEADR and LNAMES records
int Sec; // Loop counter
uint32 NameI; // Name index
// Make first record in output file = Translator header
ToFile.StartRecord(OMF_THEADR);
// Remove path from file name and limit length
char * ShortName = CLibrary::ShortenMemberName(OutputFileName);
ToFile.PutString(ShortName);
ToFile.EndRecord();
// Make LNAMES record containing names of segments, groups and classes
ToFile.StartRecord(OMF_LNAMES);
// Store default group and class names
ToFile.PutString("FLAT"); // 1: FLAT = group name
ToFile.PutString("CODE"); // 2: CODE = class name for code
ToFile.PutString("DATA"); // 3: DATA = class name for data segment
ToFile.PutString("BSS"); // 4: BSS = class name for uninitialized data
ToFile.PutString("CONST"); // 5: CONST = class name for readonly data
NameI = OMF_LNAME_LAST + 1; // Index of next name
// Get segment names
for (Sec = 0; Sec < SectionBufferNum; Sec++) {
if (SectionBuffer[Sec].NewNameI == NameI) {
// Found next segment name to add
// Check if current record too big
if (ToFile.GetSize() >= 1024 - 256) { // Max size = 1024
ToFile.EndRecord(); // End current record
ToFile.StartRecord(OMF_LNAMES); // Start new LNAMES record
}
// Store name of this segment
ToFile.PutString(NameBuffer.Buf() + SectionBuffer[Sec].NewName);
NameI++; // Ready for next name
}
}
// End LNAMES record
ToFile.EndRecord();
}
void CCOF2OMF::MakeSEGDEF() {
// Make SEGDEF and GRPDEF records
int Sec; // Index into SectionBuffer
uint32 SegNum = 0; // Segment number in new file
OMF_SAttrib Attr; // Segment attributes bitfield
uint32 align; // Alignment in new file
// Loop through SectionBuffer
for (Sec = 0; Sec < SectionBufferNum; Sec++) {
if (SectionBuffer[Sec].NewNumber == SegNum+1 && SectionBuffer[Sec].NewNameI) {
// New segment found
SegNum++; // Segment number
// Make a SEGDEF record for this segment
ToFile.StartRecord(OMF_SEGDEF + 1); // Odd record number = 32 bit
// Attributes bitfield
Attr.u.P = 1; // Indicate 32 bit segment
Attr.u.B = 0; // 1 indicates 4 Gbytes
Attr.u.C = 2; // Indicates public combination
// Translate alignment
switch(SectionBuffer[Sec].Align) {
case 0: // Align by 1
align = 1; break;
case 1: // Align by 2
align = 2; break;
case 2: // Align by 4
align = 5; break;
case 3: // Align by 8 not supported, use 16
case 4: // Align by 16
align = 3; break;
default: // 32 or higher. Use 'page' alignment
// Note: this gives 256 on some systems, 4096 on other systems
align = 4;
if (SectionBuffer[Sec].Align > 8) {
err.submit(1205, 1 << SectionBuffer[Sec].Align); // Warning: alignment not supported
}
}
Attr.u.A = align; // Put alignment into bitfield
ToFile.PutByte(Attr.b); // Save attributes bitfield
// Segment length
ToFile.PutNumeric(SectionBuffer[Sec].SegmentSize);
// Segment name given by index into LNAMES record
ToFile.PutIndex(SectionBuffer[Sec].NewNameI);
// Class name index
ToFile.PutIndex(SectionBuffer[Sec].Class);
// Overlay index (ignored)
ToFile.PutIndex(0);
// End SEGDEF record
ToFile.EndRecord();
}
}
// Make GRPDEF record for the FLAT group
ToFile.StartRecord(OMF_GRPDEF); // Strart GRPDEF record
ToFile.PutIndex(OMF_LNAME_FLAT); // Index of name "FLAT"
// No need to put segment indices into the GRPDEF record when group is FLAT
// End GRPDEF record
ToFile.EndRecord();
}
void CCOF2OMF::MakeEXTDEF() {
// Make EXTDEF records
uint32 j; // SymbolBuffer entry index
uint32 ExtSymNum = 0; // External symbol number
if (NumExternalSymbols > 0) { // Are there any external symbols?
// Make EXTDEF record for one or more symbols
ToFile.StartRecord(OMF_EXTDEF); // Start record
// Loop through SymbolBuffer
for (j = 0; j < SymbolBuffer.GetNumEntries(); j++) {
if (SymbolBuffer[j].Scope == S_EXTERNAL && SymbolBuffer[j].NewIndex == ExtSymNum+1) {
// Found external symbol
ExtSymNum++; // Symbol number
// Check if current record too big
if (ToFile.GetSize() >= 1024 - 257) {// Max size = 1024
ToFile.EndRecord(); // End current record
ToFile.StartRecord(OMF_EXTDEF); // Start new EXTDEF record
}
// Put symbol name in record
ToFile.PutString(NameBuffer.Buf() + SymbolBuffer[j].Name);
// Type index
ToFile.PutIndex(0); // Not used any more
}
}
ToFile.EndRecord(); // End EXTDEF record
}
}
void CCOF2OMF::MakePUBDEF() {
// Make PUBDEF records
uint32 j; // SymbolBuffer entry index
uint32 PubSymNum = 0; // Public symbol number
// Loop through SymbolBuffer
for (j = 0; j < SymbolBuffer.GetNumEntries(); j++) {
if (SymbolBuffer[j].Scope == S_PUBLIC && SymbolBuffer[j].NewIndex == PubSymNum+1) {
// Found public symbol
PubSymNum++; // Symbol number
// Make PUBDEF record for this symbol
ToFile.StartRecord(OMF_PUBDEF + 1); // Start new PUBDEF record, 32 bit
// Group index
uint32 Group = SymbolBuffer[j].Segment ? OMF_LNAME_FLAT : 0; // Group = FLAT, except for absolute symbols
ToFile.PutIndex(Group); // Group name index
// Segment index
ToFile.PutIndex(SymbolBuffer[j].Segment);
// Base frame field if segment = 0
if (SymbolBuffer[j].Segment == 0) ToFile.PutWord(0);
// Put symbol name in record
ToFile.PutString(NameBuffer.Buf() + SymbolBuffer[j].Name);
// Offset relative to segment
ToFile.PutNumeric(SymbolBuffer[j].Offset);
// Type index
ToFile.PutIndex(0); // Not used any more
// End record
ToFile.EndRecord(); // End PUBDEF record
}
}
}
void CCOF2OMF::MakeLEDATA() {
/*
This function makes both LEDATA records, containing binary data, and FIXUPP
records, containing relocations.
The function is quite complicated because the LEDATA and FIXUPP records are
mutually interdependent. Some explanation is in place here.
I am using the word segment for the collection of all sections in the old file
having the same name. A section is a record of binary data in the old file.
Each section is stored as one or more LEDATA records in the new file.
A segment may thus be split into multiple sections, which again may be split
into multiple LEDATA records. The sections must be aligned according to the
specified alignment for the segment. The LEDATA records need not be aligned,
and they may be misaligned for reasons explained below.
Each LEDATA record is followed by a FIXUPP record containing all relocations
referring to a source in the LEDATA record, if any.
The size of a LEDATA record is limited to 1024 bytes because each entry in
the FIXUPP record has only 10 bits for addressing it. Some linkers impose
the 1024 bytes size limit to all OMF records, although this limitation is
strictly necessary only for LEDATA records. If the code has many relocations
then it may be necessary to make a LEDATA record smaller than 1024 bytes
in order to avoid that the corresponding FIXUPP record becomes bigger than
1024 bytes. Furthermore, the size of a LEDATA record may need adjustment to
avoid that a relocation source crosses a LEDATA record boundary.
I have stored all relocations in a temporary list RelocationBuffer which is
sorted by relocation source address in order to make it easier to find all
relocations with a source address in the current LEDATA record.
*/
int Segment; // Segment index in new file
int OldSection; // Section index in old file
uint32 SegOffset; // Offset of section relative to segment
uint32 SectOffset; // Offset of LEDATA record relative to section
uint32 CutOff; // Size limit for splitting section into multiple LEDATA records
uint32 RelFirst; // Index into RelocationBuffer of first relocation for section/record
uint32 RelLast; // Index into RelocationBuffer of last relocation for record + 1
uint32 Rel; // Current index into RelocationBuffer
uint32 FrameDatum; // Frame datum field in FIXUPP record
uint32 TargetDatum; // Target datum field in FIXUPP record
uint32 TargetDisplacement; // Target displacement field in FIXUPP record
uint32 AlignmentFiller; // Number of unused bytes from end of one section to begin of next section due to alignment
SOMFRelocation Reloc0; // Reference relocation record for compare and search
OMF_SLocat Locat; // Locat bitfield for FIXUPP record
OMF_SFixData FixData; // FixData bitfield for FIXUPP record
// Loop through segment numbers
for (Segment = 1; Segment <= NumSegments; Segment++) {
SegOffset = 0; // SegOffset = 0 for first section in segment
// Search through SectionBuffer for old sections contributing to this segment
for (OldSection = 0; OldSection < SectionBufferNum; OldSection++) {
if (SectionBuffer[OldSection].NewNumber == (uint32)Segment && SectionBuffer[OldSection].Size) {
// This section contributes to Segment. Make LEDATA record(s)
if (SectionBuffer[OldSection].Offset > SegOffset) {
// Fillers needed for alignment after previous section
AlignmentFiller = SectionBuffer[OldSection].Offset - SegOffset;
}
else {
AlignmentFiller = 0;
}
SectOffset = 0; // Offset of LEDATA record relative to section start
if (AlignmentFiller > 0
&& AlignmentFiller < 4096 && AlignmentFiller < (1u << SectionBuffer[OldSection].Align)
&& SectionBuffer[OldSection].Class == OMF_LNAME_CODE) {
// This is a code segment and there is a space from previous section
// Fill the alignment space with NOP's
// Make LIDATA record with NOP's
ToFile.StartRecord(OMF_LIDATA); // Start new LEDATA record
ToFile.PutIndex(Segment); // Segment index
ToFile.PutNumeric(SegOffset); // Offset of LIDATA relative to segment
ToFile.PutNumeric(AlignmentFiller); // Repeat count
ToFile.PutWord(0); // Block count
ToFile.PutByte(1); // Byte count
ToFile.PutByte(0x90); // NOP opcode
ToFile.EndRecord(); // End LIDATA record
}
SegOffset = SectionBuffer[OldSection].Offset; // Offset of section to segment
// Search for relocations for this section
Reloc0.Section = OldSection;
Reloc0.SourceOffset = 0;
RelFirst = RelocationBuffer.FindFirst(Reloc0); // Points to first relocation for this section
RelLast = RelFirst;
// Loop for possibly more than one LEDATA records for this section
while (SectOffset < SectionBuffer[OldSection].Size) {
CutOff = SectionBuffer[OldSection].Size - SectOffset; // Size of rest of section
if (CutOff > 1024 && SectionBuffer[OldSection].Class != OMF_LNAME_BSS) {
CutOff = 1024; // Maximum LEDATA size
}
// Search for last relocation entry
while (RelLast < NumRelocations) {
if (RelocationBuffer[RelLast].Section != (uint32)OldSection) {
break; // Reached end of relocations for this section
}
if (RelocationBuffer[RelLast].SourceOffset >= CutOff + SectOffset) {
break; // Reached size limit of LEDATA record
}
if (RelocationBuffer[RelLast].SourceOffset + 4 > CutOff + SectOffset) {
// Relocation crosses LEDATA boundary.
// Reduce limit of LEDATA to before this relocation source
CutOff = RelocationBuffer[RelLast].SourceOffset - SectOffset;
if (CutOff == 0) {
err.submit(2302); // Relocation source extends beyond end of section.
CutOff = 4; // Prevent infinite loop
}
break;
}
if (RelLast - RelFirst > 100) {
// FIXUPP record will become too big. End LEDATA record here
CutOff = RelocationBuffer[RelLast].SourceOffset - SectOffset;
break;
}
RelLast++;
} // End of search for last relocation entry for this LEDATA
if (SectionBuffer[OldSection].Class == OMF_LNAME_BSS) {
// BSS: Unitialized data section needs no LEDATA record and no FIXUPP
if (RelLast > RelFirst) {
// Error: Relocation of uninitialized data
err.submit(2041);
}
}
else {
// Section contains initialized data. Needs LEDATA and FIXUPP records
// Make LEDATA record for section data
ToFile.StartRecord(OMF_LEDATA + 1);// Start new LEDATA record, 32 bit
// Segment index
ToFile.PutIndex(Segment);
// Offset of LEDATA relative to segment
ToFile.PutNumeric(SegOffset + SectOffset);
// Binary data
ToFile.PutBinary(Buf() + SectionBuffer[OldSection].psechdr->PRawData + SectOffset, CutOff);
// End LEDATA record
ToFile.EndRecord();
if (RelLast > RelFirst) { // If there are any relocations
// Make FIXUPP record with (RelLast-RelFirst) relocation entries
ToFile.StartRecord(OMF_FIXUPP + 1); // Start FIXUPP record, 32 bit
// Loop through relocations
for (Rel = RelFirst; Rel < RelLast; Rel++) {
if (RelocationBuffer[Rel].Mode < 0) {
// Unsupported mode. Make error message
err.submit(2030, RelocationBuffer[Rel].TargetOffset); // TargetOffset contains COFF relocation mode
continue;
}
// Make Locat word bitfield
Locat.s.one = 1; // Indicates FIXUP subrecord
Locat.s.M = RelocationBuffer[Rel].Mode; // Direct / EIP-relative
Locat.s.Location = 9; // Indicates 32-bit offset
// Offset of source relative to section (10 bits)
uint32 RelocOffset = RelocationBuffer[Rel].SourceOffset - SectOffset; // Offset of relocation source to begin of LEDATA record
if (RelocOffset >= 1024) err.submit(9000); // Check that it fits into 10 bits
Locat.s.Offset = RelocOffset;
// Make FixData byte bitfield
FixData.b = 0; // Start with all bits 0
if (RelocationBuffer[Rel].Scope == S_LOCAL) {
// Local target
FixData.s.Target = 0; // Target method T0 or T4: Target = segment
FixData.s.Frame = 1; // Frame method F1: specified by a group index (FLAT)
FrameDatum = OMF_LNAME_FLAT; // Target frame = FLAT group
TargetDatum = RelocationBuffer[Rel].TargetSegment; // Fixup target = segment
TargetDisplacement = RelocationBuffer[Rel].TargetOffset; // Displacement or addend (?)
}
else {
// External symbol target
FixData.s.Frame = 5; // Frame method F5: Frame specified by target, not here
FixData.s.Target = 2; // Target method T2 or T6: Target specified by EXTDEF index
TargetDatum = RelocationBuffer[Rel].TargetSegment; // Index into EXTDEF
TargetDisplacement = RelocationBuffer[Rel].TargetOffset; // This is zero. Any addend is inline
}
if (TargetDisplacement) {
FixData.s.P = 0; // Displacement field present
}
else {
FixData.s.P = 1; // Displacement field absent
}
// Put these data into record
// Locat bytes in reverse order:
ToFile.PutByte(Locat.bytes[1]);
ToFile.PutByte(Locat.bytes[0]);
// FixData byte
ToFile.PutByte(FixData.b);
// Frame datum field only if FixData.F = 0 and Frame < 4
if (FixData.s.Frame < 4) ToFile.PutIndex(FrameDatum);
// Target datum field if FixData.T = 0, which it is here
ToFile.PutIndex(TargetDatum);
// Target displacement field if FixData.P = 0
if (FixData.s.P == 0) ToFile.PutNumeric(TargetDisplacement);
} // End of loop through relocation for last LEDATA
// End FIXUPP record
ToFile.EndRecord();
}
}
// Update pointers to after this LEDATA
SectOffset += CutOff;
RelFirst = RelLast;
} // End of loop for multiple LEDATA records for one section
// Find end of section
SegOffset += SectionBuffer[OldSection].Size; // End of section
} // End of if section in segment
} // End of loop through multiple sections for same segment
} // End of loop through segments
}
void CCOF2OMF::MakeMODEND() {
// Make MODEND record and finish file
ToFile.StartRecord(OMF_MODEND); // Start MODEND record
ToFile.PutByte(0); // Module type field. 0 if not a startup module with start address
ToFile.EndRecord(); // End MODEND record
}