QuantX: Complete rewrite based on my reverse engineering of the XPR0 format as used by Steel Battalion and Steel Battalion: Line of Contact

2023-09-22T03:17:02Z

Complete rewrite based on my reverse engineering of the XPR0 format as used by Steel Battalion and Steel Battalion: Line of Contact

JayFoxRox: Add some rough information about XPRs

2019-10-24T16:32:44Z

Add some rough information about XPRs

New page

'''XPR''' probably stands for '''Xbox Packed Resource'''. It's a structure and file-format used by the [[Microsoft XDK]].
It is being used in parts of [[XAPI]].

XPRs can store a variety of different data types that are useful for Xbox D3D.
XPRs are storing data similar to internal structures in the D3D driver. So D3D has mechanisms to simply load such resources into D3D objects (by moving them into GPU accessible memory).

The structure is something like this{{FIXME|Untested pseudo-code}}:

<pre>
struct {
char magic[4]; // Always "XPR0" / 0x30525058
uint32_t size; // Size of XPR (including magic and this field)
uint32_t header_size; // Size of the following header (always 2048?)
} XPR;
</pre>

This is followed by:

<pre>
union {
struct {
union {
uint32_t flags; // Type information and who "owns" this resource
struct {
uint32_t ref_count:16; // (lowest bits)
uint32_t type:3;
uint32_t unk3:13; // (highest bits)
};
};
union { // Vertexbuffer (type 0x0)
...
} vertexbuffer;
union { // Indexbuffer (type 0x1)
...
} indexbuffer;
union { // Unknown (type 0x2)
...
} ...;
union { // Unknown (type 0x3)
...
} ...;
union { // Texture (type 0x4)
uint32_t unk0; // Always 0?
uint32_t unk1; // Always 0?
uint32_t format; // GPU register
uint32_t unk2; // Always 0?
uint32_t end; // Always 0xFFFFFFFF
} texture;
union { // Unknown (type 0x5)
...
} ...;
union { // Unknown (type 0x6)
...
} ...;
union { // Unknown (type 0x7)
...
} ...;
};
uint8_t pad[2048]; // Padded with 0xAD bytes
} XPR_header;
</pre>

{{FIXME|one of the unknowns in the texture is probably offset into data}}

The headers are then followed by the resource data.

@@ Line 5: / Line 5: @@
 XPRs are storing data similar to internal structures in the D3D driver. So D3D has mechanisms to simply load such resources into D3D objects (by moving them into GPU accessible memory).
-The structure is something like this{{FIXME|Untested pseudo-code}}:
+An XPR header consists of a number of resource entries which each look something like this{{FIXME|Incomplete}}:
 <pre>
 struct {
-   char magic[4]; // Always "XPR0" / 0x30525058
+   union {
-  uint32_t size; // Size of XPR (including magic and this field)
+    uint32_t resource_type; // Type information and who "owns" this resource
-  uint32_t header_size; // Size of the following header (always 2048?)
+    struct {
-} XPR;
+      uint32_t ref_count:16; // (lowest bits)
-</pre>
+      uint32_t type:3;
+      uint32_t unk3:13; // (highest bits)
-This is followed by:
+    };
-<pre>
+  union {
-union {
+     struct XPR_Vertexbuffer; // Vertexbuffer (type 0x0)
        ...
-     } vertexbuffer;
+     } XPR_Vertexbuffer;
-     union { // Indexbuffer (type 0x1)
+     struct { // Indexbuffer (type 0x1)
        ...
-     } indexbuffer;
+     } XPR_Indexbuffer;
-     union { // Unknown (type 0x2)
+     struct { // Unknown (type 0x2)
        ...
      } ...;
-     union { // Unknown (type 0x3)
+     struct { // Unknown (type 0x3)
        ...
      } ...;
-     union { // Texture (type 0x4)
+     struct { // Texture (type 0x4)
-       uint32_t unk0; // Always 0?
+       ...;
-      uint32_t unk1; // Always 0?
+     } XPR_Texture;
-      uint32_t format; // GPU register
+     struct { // Unknown (type 0x5)
        ...
      } ...;
-     union { // Unknown (type 0x6)
+     struct { // Unknown (type 0x6)
        ...
      } ...;
-     union { // Unknown (type 0x7)
+     struct { // Unknown (type 0x7)
        ...
      } ...;
    };
-  uint8_t pad[2048]; // Padded with 0xAD bytes
+} XPR_Resource;
 </pre>
-{{FIXME|one of the unknowns in the texture is probably offset into data}}
+The XPR header as a whole looks like this:
 The headers are then followed by the resource data.

XPR - Revision history

QuantX: Complete rewrite based on my reverse engineering of the XPR0 format as used by Steel Battalion and Steel Battalion: Line of Contact

JayFoxRox: Add some rough information about XPRs