Optimize layout of 'struct blob_descriptor'

[wimlib] / include / wimlib / blob_table.h

diff --git a/include/wimlib/blob_table.h b/include/wimlib/blob_table.h
index b71abca538f6c52fa62c632ff72a80775899be89..e273de2531b8fd16280b5737c6421526e32afb75 100644 (file)
--- a/include/wimlib/blob_table.h
+++ b/include/wimlib/blob_table.h
@@ -77,32 +77,6 @@ struct blob_descriptor {
        /* Uncompressed size of this blob  */
        u64 size;
 
-       /* One of the `enum blob_location' values documented above.  */
-       u32 blob_location : 4;
-
-       /* 1 iff this blob contains "metadata" as opposed to data.  */
-       u32 is_metadata : 1;
-
-       /* 1 iff the SHA-1 message digest of this blob is unknown.  */
-       u32 unhashed : 1;
-
-       /* Temporary fields used when writing blobs; set as documented for
-        * prepare_blob_list_for_write().  */
-       u32 unique_size : 1;
-       u32 will_be_in_output_wim : 1;
-
-       /* Set to 1 if this blob represents a metadata resource that has been
-        * changed.  In such cases, the hash cannot be used to verify the data
-        * if the metadata resource is read again.  (This could be avoided if we
-        * used separate fields for input/output checksum, but most blobs
-        * wouldn't need this.)  */
-       u32 dont_check_metadata_hash : 1;
-
-       u32 may_send_done_with_file : 1;
-
-       /* Only used by wimlib_export_image() */
-       u32 was_exported : 1;
-
        union {
                /*
                 * For unhashed == 0: 'hash' is the SHA-1 message digest of the
@@ -151,6 +125,32 @@ struct blob_descriptor {
        u16 num_opened_fds;
 #endif
 
+       /* One of the `enum blob_location' values documented above.  */
+       u16 blob_location : 4;
+
+       /* 1 iff this blob contains "metadata" as opposed to data.  */
+       u16 is_metadata : 1;
+
+       /* 1 iff the SHA-1 message digest of this blob is unknown.  */
+       u16 unhashed : 1;
+
+       /* Temporary fields used when writing blobs; set as documented for
+        * prepare_blob_list_for_write().  */
+       u16 unique_size : 1;
+       u16 will_be_in_output_wim : 1;
+
+       /* Set to 1 if this blob represents a metadata resource that has been
+        * changed.  In such cases, the hash cannot be used to verify the data
+        * if the metadata resource is read again.  (This could be avoided if we
+        * used separate fields for input/output checksum, but most blobs
+        * wouldn't need this.)  */
+       u16 dont_check_metadata_hash : 1;
+
+       u16 may_send_done_with_file : 1;
+
+       /* Only used by wimlib_export_image() */
+       u16 was_exported : 1;
+
        /* Specification of where this blob's data is located.  Which member of
         * this union is valid is determined by the @blob_location field.  */
        union {
@@ -158,37 +158,45 @@ struct blob_descriptor {
                struct {
                        struct wim_resource_descriptor *rdesc;
                        u64 offset_in_res;
+
+                       /* Links together blobs that share the same underlying
+                        * WIM resource.  The head is rdesc->blob_list.  */
+                       struct list_head rdesc_node;
                };
 
-               /* BLOB_IN_FILE_ON_DISK
-                * BLOB_IN_WINNT_FILE_ON_DISK
-                * BLOB_WIN32_ENCRYPTED  */
                struct {
-                       tchar *file_on_disk;
-                       struct wim_inode *file_inode;
-               };
 
-               /* BLOB_IN_ATTACHED_BUFFER */
-               void *attached_buffer;
+                       union {
 
-#ifdef WITH_FUSE
-               /* BLOB_IN_STAGING_FILE  */
-               struct {
-                       char *staging_file_name;
-                       int staging_dir_fd;
-               };
-#endif
+                               /* BLOB_IN_FILE_ON_DISK
+                                * BLOB_IN_WINNT_FILE_ON_DISK
+                                * BLOB_WIN32_ENCRYPTED  */
+                               struct {
+                                       tchar *file_on_disk;
+                                       struct wim_inode *file_inode;
+                               };
 
-#ifdef WITH_NTFS_3G
-               /* BLOB_IN_NTFS_VOLUME  */
-               struct ntfs_location *ntfs_loc;
-#endif
-       };
+                               /* BLOB_IN_ATTACHED_BUFFER */
+                               void *attached_buffer;
+
+                       #ifdef WITH_FUSE
+                               /* BLOB_IN_STAGING_FILE  */
+                               struct {
+                                       char *staging_file_name;
+                                       int staging_dir_fd;
+                               };
+                       #endif
 
-       /* Links together blobs that share the same underlying WIM resource.
-        * The head is the 'blob_list' member of
-        * 'struct wim_resource_descriptor'.  */
-       struct list_head rdesc_node;
+                       #ifdef WITH_NTFS_3G
+                               /* BLOB_IN_NTFS_VOLUME  */
+                               struct ntfs_location *ntfs_loc;
+                       #endif
+                       };
+
+                       /* List link for per-WIM-image list of unhashed blobs */
+                       struct list_head unhashed_list;
+               };
+       };
 
        /* Temporary fields  */
        union {
@@ -253,10 +261,6 @@ struct blob_descriptor {
                /* Links original list of blobs in the read-write mounted image.  */
                struct list_head orig_blob_list;
        };
-
-       /* Links blobs that are still unhashed after being been added to a WIM.
-        */
-       struct list_head unhashed_list;
 };
 
 extern struct blob_table *