[VFS] Improve STFS GetBlockHash function - now gets hash from correct hash table.

This should hopefully allow Xenia to be more compatible with larger / more made-use-of profiles.

Each hash table actually consists of two hash tables for redundancy, which table is used is decided by the hash table level above it.
Previously there was some code to try swapping which table to use if a flag isn't set, but the code ended up being commented out & unused...

After looking at some other X360 mod tools sources I've managed to come up with this solution, which visits each hash-level it can to retrieve the correct table number to use.
Really this is probably a little inefficient, the code I based this on would actually cache each table in memory to make these visits a lot quicker, maybe should look into doing the same here.
For packages with read_only_package() == true, this maybe isn't even necessary too - but it's probably worth keeping it as-is just in case though.

src/xenia/vfs/devices/stfs_container_device.cc

@@ -220,12 +220,6 @@ StfsContainerDevice::Error StfsContainerDevice::ReadHeaderAndVerify(
     return Error::kErrorDamagedFile;
   }
 
-  if (((header_.header_size + 0x0FFF) & 0xB000) == 0xB000) {
-    table_size_shift_ = 0;
-  } else {
-    table_size_shift_ = 1;
-  }
-
   return Error::kSuccess;
 }
 
@@ -563,16 +557,13 @@ StfsContainerDevice::Error StfsContainerDevice::ReadSTFS() {
         uint32_t block_index = start_block_index;
         size_t remaining_size = file_size;
         uint32_t info = 0x80;
-        while (remaining_size && block_index && info >= 0x80) {
+        while (remaining_size && block_index) {
           size_t block_size =
               std::min(static_cast<size_t>(0x1000), remaining_size);
           size_t offset = BlockToOffsetSTFS(block_index);
           entry->block_list_.push_back({0, offset, block_size});
           remaining_size -= block_size;
-          auto block_hash = GetBlockHash(data, block_index, 0);
+          auto block_hash = GetBlockHash(data, block_index);
-          if (table_size_shift_ && block_hash.info < 0x80) {
-            block_hash = GetBlockHash(data, block_index, 1);
-          }
           block_index = block_hash.next_block_index;
           info = block_hash.info;
         }
@@ -581,14 +572,8 @@ StfsContainerDevice::Error StfsContainerDevice::ReadSTFS() {
       parent_entry->children_.emplace_back(std::move(entry));
     }
 
-    auto block_hash = GetBlockHash(data, table_block_index, 0);
+    auto block_hash = GetBlockHash(data, table_block_index);
-    if (table_size_shift_ && block_hash.info < 0x80) {
-      block_hash = GetBlockHash(data, table_block_index, 1);
-    }
     table_block_index = block_hash.next_block_index;
-    if (table_block_index == 0xFFFFFF) {
-      break;
-    }
   }
 
   if (all_entries.size() > 0) {
@@ -611,7 +596,7 @@ size_t StfsContainerDevice::BlockToOffsetSTFS(uint64_t block_index) {
   }
 
   uint32_t num_tables = 1;  // num hashtables per block? or maybe backingblocks?
-  if ((header_.stfs_volume_descriptor.flags & 0x1) == 0x0) {
+  if (!read_only_package()) {
     num_tables++;
   }
 
@@ -623,7 +608,7 @@ size_t StfsContainerDevice::BlockToOffsetSTFS(uint64_t block_index) {
     }
   }
 
-  return xe::round_up(header_.header_size, 0x1000) + (dataBlock * 0x1000);
+  return BackingBlockToOffsetSTFS(dataBlock);
 }
 
 size_t StfsContainerDevice::BlockToOffsetSTFS_Old(uint64_t block_index) {
@@ -653,24 +638,98 @@ size_t StfsContainerDevice::BlockToOffsetSTFS_Old(uint64_t block_index) {
   return xe::round_up(header_.header_size, 0x1000) + (block << 12);
 }
 
-StfsContainerDevice::BlockHash StfsContainerDevice::GetBlockHash(
+size_t StfsContainerDevice::BackingBlockToOffsetSTFS(uint64_t backing_block) {
-    const uint8_t* map_ptr, uint32_t block_index, uint32_t table_offset) {
+  return xe::round_up(header_.header_size, 0x1000) + (backing_block * 0x1000);
-  uint32_t record = block_index % 0xAA;
+}
+
+size_t StfsContainerDevice::BlockToHashBlockOffset(uint64_t block,
+                                                   uint32_t hash_level) {
+  uint32_t numTables = 1;
+  uint32_t blockStep0 = 0xAB;
+  uint32_t blockStep1 = 0x718F;
+  if (!read_only_package()) {
+    numTables = 2;
+    blockStep0 = 0xAC;
+    blockStep1 = 0x723A;
+  }
+
+  uint64_t backing_num = 0;
+  if (hash_level == 0) {
+    backing_num = (block / 0xAA) * blockStep0;
+    if (block / 0xAA == 0) {
+      return BackingBlockToOffsetSTFS(backing_num);
+    }
+
+    backing_num = backing_num + ((block / 0x70E4) + 1) * numTables;
+    if (block / 0x70E4 == 0) {
+      return BackingBlockToOffsetSTFS(backing_num);
+    }
+  } else if (hash_level == 1) {
+    backing_num = (block / 0x70E4) * blockStep1;
+    if (block / 0x70E4 == 0) {
+      return BackingBlockToOffsetSTFS(backing_num + blockStep0);
+    }
+  } else {
+    return BackingBlockToOffsetSTFS(blockStep0);
+  }
+  return BackingBlockToOffsetSTFS(backing_num + numTables);
+}
+
+StfsContainerDevice::BlockHash StfsContainerDevice::GetHashEntry(
+    const uint8_t* map_ptr, uint32_t block_index, uint32_t level,
+    uint32_t table_offset) {
+  uint32_t record = block_index;
+  if (level == 1) {
+    record = record / 0xAA;
+  }
+  if (level == 2) {
+    record = record / 0x70E4;
+  }
+  record = record % 0xAA;
+
+  size_t hash_offset = BlockToHashBlockOffset(block_index, level);
+  if (table_offset != 0) {
+    hash_offset += 0x1000;  // use alternate hash table?
+  }
 
-  // This is a bit hacky, but we'll get a pointer to the first block after the
-  // table and then subtract one sector to land on the table itself.
-  size_t hash_offset = BlockToOffsetSTFS(
-      xe::round_up(block_index + 1, kSTFSHashSpacing) - kSTFSHashSpacing);
-  hash_offset -= bytes_per_sector();
   const uint8_t* hash_data = map_ptr + hash_offset;
 
-  // table_index += table_offset - (1 << table_size_shift_);
   const uint8_t* record_data = hash_data + record * 0x18;
   uint32_t info = xe::load_and_swap<uint8_t>(record_data + 0x14);
   uint32_t next_block_index = load_uint24_be(record_data + 0x15);
   return {next_block_index, info};
 }
 
+StfsContainerDevice::BlockHash StfsContainerDevice::GetBlockHash(
+    const uint8_t* map_ptr, uint32_t block_index) {
+  uint32_t table_offset = 0;
+  // Check RootActiveIndex flag - increment table_offset to use for root table
+  // if set
+  if (header_.stfs_volume_descriptor.flags & 2) {
+    table_offset = 1;
+  }
+
+  if (header_.stfs_volume_descriptor.total_allocated_block_count >= 0x70E4) {
+    // Get the L2 entry for the block
+    auto l2_entry = GetHashEntry(map_ptr, block_index, 2, table_offset);
+    table_offset = 0;
+    if (l2_entry.info & 0x40) {  // ActiveIndex flag
+      table_offset = 1;
+    }
+  }
+
+  if (header_.stfs_volume_descriptor.total_allocated_block_count >= 0xAA) {
+    // Get the L1 entry for this block
+    auto l1Entry = GetHashEntry(map_ptr, block_index, 1, table_offset);
+    table_offset = 0;
+    if (l1Entry.info & 0x40) {  // ActiveIndex flag
+      table_offset = 1;
+    }
+  }
+
+  return GetHashEntry(map_ptr, block_index, 0, table_offset);
+}
+
 bool StfsVolumeDescriptor::Read(const uint8_t* p) {
   descriptor_size = xe::load_and_swap<uint8_t>(p + 0x00);
   if (descriptor_size != 0x24) {

src/xenia/vfs/devices/stfs_container_device.h

@@ -183,6 +183,10 @@ class StfsContainerDevice : public Device {
   uint32_t sectors_per_allocation_unit() const override { return 1; }
   uint32_t bytes_per_sector() const override { return 4 * 1024; }
 
+  bool read_only_package() {
+    return (header_.stfs_volume_descriptor.flags & 1) != 0;
+  }
+
   StfsHeader& header() { return header_; }
 
   uint32_t ExtractToFolder(const std::wstring& dest_path);
@@ -219,9 +223,17 @@ class StfsContainerDevice : public Device {
   size_t BlockToOffsetSTFS(uint64_t block);
   size_t BlockToOffsetSTFS_Old(uint64_t block);
 
-  BlockHash GetBlockHash(const uint8_t* map_ptr, uint32_t block_index,
+  size_t BackingBlockToOffsetSTFS(uint64_t backing_block);
+
+  size_t BlockToHashBlockOffset(uint64_t block, uint32_t hash_level = 0);
+
+  StfsContainerDevice::BlockHash GetHashEntry(const uint8_t* map_ptr,
+                                              uint32_t block_index,
+                                              uint32_t level,
                                               uint32_t table_offset);
 
+  BlockHash GetBlockHash(const uint8_t* map_ptr, uint32_t block_index);
+
   std::wstring local_path_;
   std::map<size_t, std::unique_ptr<MappedMemory>> mmap_;
   size_t mmap_total_size_;
@@ -231,7 +243,6 @@ class StfsContainerDevice : public Device {
   std::unique_ptr<Entry> root_entry_;
   StfsPackageType package_type_;
   StfsHeader header_;
-  uint32_t table_size_shift_;
 
   bool use_old_algorithm_ = false;
 };