From e5ac0ac6315289378ac5b6cd875032c778875672 Mon Sep 17 00:00:00 2001
From: Andy McFadden <fadden@fadden.com>
Date: Thu, 25 Jun 2020 14:12:29 -0700
Subject: [PATCH] Fix OMF version confusion

VERSION=0/1/2 corresponds, simply, to v0/v1/v2, where v0 was only
used for some older 8-bit Orca/M stuff.  v2.1 can be detected by
looking for the optional "tempOrg" field.

Also, allow the disk version number to be set to zero in 2IMG images.
---
 app/TwoImgPropsDialog.cpp |  2 +-
 reformat/Disasm.cpp       | 24 +++++++++++++++++-------
 reformat/Disasm.h         | 11 ++++++-----
 3 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/app/TwoImgPropsDialog.cpp b/app/TwoImgPropsDialog.cpp
index 427d259..2b1c0c4 100644
--- a/app/TwoImgPropsDialog.cpp
+++ b/app/TwoImgPropsDialog.cpp
@@ -99,7 +99,7 @@ void TwoImgPropsDialog::DoDataExchange(CDataExchange* pDX)
             fpHeader->fFlags |= (dosVolNum & TwoImgHeader::kDOSVolumeMask);
 
             CString appStr, errMsg;
-            if (dosVolNum < 1 || dosVolNum > 254) {
+            if (dosVolNum < 0 || dosVolNum > 254) {
                 CheckedLoadString(&appStr, IDS_MB_APP_NAME);
                 CheckedLoadString(&errMsg, IDS_VALID_VOLNAME_DOS);
                 MessageBox(errMsg, appStr, MB_OK);
diff --git a/reformat/Disasm.cpp b/reformat/Disasm.cpp
index 94b76e6..5db9486 100644
--- a/reformat/Disasm.cpp
+++ b/reformat/Disasm.cpp
@@ -937,9 +937,10 @@ void ReformatDisasm16::PrintHeader(const OMFSegmentHeader* pSegHdr,
 
     const char* versStr;
     switch (pSegHdr->GetVersion()) {
-    case 0:     versStr = "1.0";        break;
-    case 1:     versStr = "2.0";        break;
-    case 2:     versStr = "2.1";        break;
+    case 0:     versStr = "0.0";        break;
+    case 1:     versStr = "1.0";        break;
+    case 2:     versStr = "2.0";        break;
+    case 0x82:  versStr = "2.1";        break;
     default:    versStr = "(unknown)";  break;
     }
 
@@ -1058,8 +1059,9 @@ bool OMFSegmentHeader::Unpack(const uint8_t* srcBuf, long srcLen, int fileType)
         return false;
     }
 
+    fRevision = 0;
     if (fVersion == 0) {
-        /* unpack OMF v1.0 */
+        /* unpack OMF v0.0 (not actually used for 16-bit code?) */
         if (srcLen < kV0HdrMinSize)
             return false;
 
@@ -1086,7 +1088,7 @@ bool OMFSegmentHeader::Unpack(const uint8_t* srcBuf, long srcLen, int fileType)
         else
             fDispData = fDispName + fLabLen;
     } else if (fVersion == 1) {
-        /* unpack OMF v2.0 */
+        /* unpack OMF v1.0 */
         if (srcLen < kV1HdrMinSize)
             return false;
         fBlockCnt = Get32LE(srcBuf + 0x00);
@@ -1124,7 +1126,7 @@ bool OMFSegmentHeader::Unpack(const uint8_t* srcBuf, long srcLen, int fileType)
         fKind = 0;
         fTempOrg = 0;
     } else {
-        /* unpack OMF v2.1 */
+        /* unpack OMF v2.x */
         if (srcLen < kV2HdrMinSize)
             return false;
         fByteCnt = Get32LE(srcBuf + 0x00);
@@ -1144,7 +1146,13 @@ bool OMFSegmentHeader::Unpack(const uint8_t* srcBuf, long srcLen, int fileType)
         fEntry = Get32LE(srcBuf + 0x24);
         fDispName = Get16LE(srcBuf + 0x28);
         fDispData = Get16LE(srcBuf + 0x2a);
-        fTempOrg = Get32LE(srcBuf + 0x2c);
+        if (fDispName > 0x2c) {
+            // v2.1 adds a 4-byte "tempOrg" field
+            fTempOrg = Get32LE(srcBuf + 0x2c);
+            fRevision = 1;
+        } else {
+            fTempOrg = 0;
+        }
 
         fBlockCnt = 0;
         fType = 0;
@@ -1192,6 +1200,8 @@ bool OMFSegmentHeader::Unpack(const uint8_t* srcBuf, long srcLen, int fileType)
         fLoadName[kLoadNameLen] = '\0';
 
         segName +=  kLoadNameLen;
+    } else {
+        fLoadName[0] = '\0';
     }
 
     if (fLabLen == 0) {
diff --git a/reformat/Disasm.h b/reformat/Disasm.h
index eda5aae..9c41716 100644
--- a/reformat/Disasm.h
+++ b/reformat/Disasm.h
@@ -227,7 +227,7 @@ public:
         kTypePathName       = 0x04,
         kTypeLibraryDict    = 0x08,
         kTypeInit           = 0x10,
-        kTypeAbsoluteBank   = 0x11,
+        kTypeAbsoluteBank   = 0x11,     // v1.0 only
         kTypeDPStack        = 0x12,
     } SegmentType;
     typedef enum SegmentFlag {
@@ -241,7 +241,7 @@ public:
         kFlagDynamic,
     } SegmentFlag;
 
-    uint8_t GetVersion(void) const { return fVersion; }
+    uint8_t GetVersion(void) const { return fVersion + (fRevision << 7); }
     uint32_t GetSegmentLen(void) const { return fByteCnt; }
     SegmentType GetSegmentType(void) const;
     bool GetSegmentFlag(SegmentFlag flag) const;
@@ -254,11 +254,11 @@ public:
 
     // some of these must be public in VC++6.0
     enum {
-        kMaxVersion         = 2,            // v0/1/2 == OMF 1.0 / 2.0 / 2.1
+        kMaxVersion         = 2,            // v0/1/2 == OMF 0.0 / 1.0 / 2.x
         kLoadNameLen        = 10,
         kV0HdrMinSize       = 0x25,
         kV1HdrMinSize       = 0x2c + kLoadNameLen,
-        kV2HdrMinSize       = 0x30 + kLoadNameLen,
+        kV2HdrMinSize       = kV1HdrMinSize,    // 2.1 is slightly larger; handle that elsewhere
         kHdrMinSize         = kV0HdrMinSize,    // smallest of the three
         kExpectedNumLen     = 4,
         kExpectedBankSize   = 65536,
@@ -277,13 +277,14 @@ private:
     }
 
     uint32_t    fBlockCnt;          // v0/v1
-    uint32_t    fByteCnt;           // v2
+    uint32_t    fByteCnt;           // [v1]/v2
     uint32_t    fResSpc;
     uint32_t    fLength;
     uint8_t     fType;              // v0/v1
     uint8_t     fLabLen;
     uint8_t     fNumLen;            // (always 4)
     uint8_t     fVersion;           // (0, 1, or 2)
+    uint8_t     fRevision;          // fictitious field; holds 0 or 1
     uint32_t    fBankSize;          // (always 65536)
     uint16_t    fKind;              // v2
     uint32_t    fOrg;