Finished ESM header decoder

esm/reader.cpp

@@ -12,6 +12,9 @@ using namespace std;
 /* A structure used for holding fixed-length strings. In the case of
    LEN=4, it can be more efficient to match the string as a 32 bit
    number, therefore the struct is implemented as a union with an int.
+
+   TODO: Merge with SliceArray, find how to do string-specific
+   template specializations in a useful manner.
  */
 template <int LEN>
 union NAME_T
@@ -42,6 +45,7 @@ union NAME_T
 
 typedef NAME_T<4> NAME;
 typedef NAME_T<32> NAME32;
+typedef NAME_T<64> NAME64;
 typedef NAME_T<256> NAME256;
 
 class ESMReader
@@ -53,6 +57,9 @@ class ESMReader
 
   NAME recName, subName;
 
+  // True if subName has been read but not used.
+  bool subCached;
+
 #pragma pack(push)
 #pragma pack(1)
   struct HEDRstruct
@@ -67,9 +74,19 @@ class ESMReader
     NAME256 desc;       // File description
     int records;        // Number of records? Not used.
   };
+
+  struct SaveData
+  {
+    float pos[6];     // Player position and rotation
+    NAME64 cell;      // Cell name
+    float unk2;       // Unknown value - possibly game time?
+    NAME32 player;    // Player name
+
+  };
 #pragma pack(pop)
 
   HEDRstruct header;
+  SaveData saveData;
 
 public:
   enum Version
@@ -80,9 +97,9 @@ public:
 
   enum FileType
     {
-      FT_ESP = 0,
-      FT_ESM = 1,
-      FT_ESS = 32
+      FT_ESP = 0,       // Plugin
+      FT_ESM = 1,       // Master
+      FT_ESS = 32       // Savegame
     };
 
   void open(Mangle::Stream::StreamPtr _esm, const string &name)
@@ -92,6 +109,7 @@ public:
     leftFile = esm->size();
     leftRec = 0;
     leftSub = 0;
+    subCached = false;
     recName.val = 0;
     subName.val = 0;
 
@@ -111,16 +129,38 @@ public:
        header.version != VER_13)
       fail("Unsupported file format version");
 
-    cout << "Author: " << header.author.toString() << endl;
     cout << "Description: " << header.desc.toString() << endl;
+    cout << "Author: " << header.author.toString() << endl;
 
     while(isNextSub("MAST"))
       {
-        // TODO: read master data here
-        skipHSub();
+        cout << "Master: " << getHString() << endl;
+        cout << "  size: " << getHNLong("DATA") << endl;
       }
 
-    // TODO: Read extra savegame data
+    if(header.type == FT_ESS)
+      {
+        // Savegame-related data
+
+        // Player position etc
+        getHNT(saveData, "GMDT");
+
+        /* Image properties, five ints. Is always:
+           Red-mask:   0xff0000
+           Blue-mask:  0x00ff00
+           Green-mask: 0x0000ff
+           Alpha-mask: 0x000000
+           Bpp:        32
+         */
+        getSubNameIs("SCRD");
+        skipHSubSize(20);
+
+        /* Savegame screenshot:
+           128x128 pixels * 4 bytes per pixel
+         */
+        getSubNameIs("SCRS");
+        skipHSubSize(65536);
+      }
   }
 
   void open(const string &file)
@@ -143,6 +183,13 @@ public:
     getHT(x);
   }
 
+  int64_t getHNLong(const char *name)
+  {
+    int64_t val;
+    getHNT(val, name);
+    return val;
+  }
+
   // Get data of a given type/size, including subrecord header
   template <typename X>
   void getHT(X &x)
@@ -153,9 +200,30 @@ public:
     getT(x);
   }
 
+  string getHString()
+  {
+    getSubHeader();
+
+    // Hack to make MultiMark.esp load. Zero-length strings do not
+    // occur in any of the official mods, but MultiMark makes use of
+    // them. For some reason, they break the rules, and contain a byte
+    // (value 0) even if the header says there is no data. If
+    // Morrowind accepts it, so should we.
+    if(leftSub == 0)
+      {
+        // Skip the following zero byte
+        leftRec--;
+        char c;
+        esm->read(&c,1);
+        return "";
+      }
+
+    return getString(leftSub);
+  }
+
   /*************************************************************************
    *
-   *  Low level reading methods
+   *  Low level sub-record methods
    *
    *************************************************************************/
 
@@ -167,26 +235,58 @@ public:
       fail("Expected subrecord " + string(name) + " but got " + subName.toString());
   }
 
-  // Get the next record name
-  NAME getRecName()
+  /** Checks if the next sub record name matches the parameter. If it
+      does, it is read into 'subName' just as if getSubName() was
+      called. If not, the read name will still be available for future
+      calls to getSubName(), isNextSub() and getSubNameIs().
+   */
+  bool isNextSub(const char* name)
   {
-    if(!hasMoreRecs())
-      fail("No more records, getRecName() failed");
-    getName(recName);
-    leftFile -= 4;
-    return recName;
+    if(!leftRec) return false;
+
+    getSubName();
+
+    // If the name didn't match, then mark the it as 'cached' so it's
+    // available for the next call to getSubName.
+    subCached = (subName != name);
+
+    // If subCached is false, then subName == name.
+    return !subCached;
   }
 
-  // Read subrecord name. I've optimized this slightly, since it gets
-  // called a LOT.
+  // Read subrecord name. This gets called a LOT, so I've optimized it
+  // slightly.
   void getSubName()
     {
+      // If the name has already been read, do nothing
+      if(subCached)
+        {
+          subCached = false;
+          return;
+        }
+
       // Don't bother with error checking, we will catch an EOF upon
       // reading the subrecord data anyway.
       esm->read(subName.name, 4);
       leftRec -= 4;
     }
 
+  // Skip current sub record, including header (but not including
+  // name.)
+  void skipHSub()
+    {
+      getSubHeader();
+      esm->seek(esm->tell()+leftSub);
+    }
+
+  // Skip sub record and check its size
+  void skipHSubSize(int size)
+    {
+      skipHSub();
+      if(leftSub != size)
+	fail("skipHSubSize() mismatch");
+    }
+
   /* Sub-record head This updates leftRec beyond the current
      sub-record as well. leftSub contains size of current sub-record.
   */
@@ -195,16 +295,34 @@ public:
       if(leftRec < 4)
 	fail("End of record while reading sub-record header");
 
+      // Get subrecord size
       getT(leftSub);
 
       // Adjust number of record bytes left
       leftRec -= leftSub + 4;
 
-      // Check that sizes add up
+      // Check that sizes added up
       if(leftRec < 0)
 	fail("Not enough bytes left in record for this subrecord.");
     }
 
+
+  /*************************************************************************
+   *
+   *  Low level record methods
+   *
+   *************************************************************************/
+
+  // Get the next record name
+  NAME getRecName()
+  {
+    if(!hasMoreRecs())
+      fail("No more records, getRecName() failed");
+    getName(recName);
+    leftFile -= 4;
+    return recName;
+  }
+
   /* Read record header. This updatesleftFile BEYOND the data that
      follows the header, ie beyond the entire record. You should use
      leftRec to orient yourself inside the record itself.
@@ -232,11 +350,34 @@ public:
 
   bool hasMoreRecs() { return leftFile > 0; }
 
+
+  /*************************************************************************
+   *
+   *  Lowest level data reading and misc methods
+   *
+   *************************************************************************/
+
   template <typename X>
-  void getT(X &x) { esm->read(&x, sizeof(X)); }
+  void getT(X &x)
+  {
+    int t = esm->read(&x, sizeof(X));
+    if(t != sizeof(X))
+      fail("Read error");
+  }
   void getName(NAME &name) { getT(name); }
   void getUint(uint32_t &u) { getT(u); }
 
+  // Read the next size bytes and return them as a string
+  std::string getString(int size)
+  {
+    // Not very optimized, but we'll fix that later
+    char *ptr = new char[size];
+    esm->read(ptr,size);
+    string res(ptr,size);
+    delete[] ptr;
+    return res;
+  }
+
   /// Used for error handling
   void fail(const std::string &msg)
     {