AnyPS5/docs/dev/debt/libSceJxr.md

# libSceJxr technical debt

### GUID exports

- [GUID data exports](../../../core/libs/prx/libSceJxr/src/GuidExports.cpp) use 84 values from the pinned JXR header. Their NIDs and bytes match version-labelled images; the labels are not authenticated. Runtime behavior on a console and complete consumer coverage are unverified. Four additional 4-byte interface identifiers have names and values matching the pinned upstream JXR implementation and both version-labelled images; their relative placement in a guest image and use by consumers are unverified. One older 8-byte writable object has a relocation and no matching later-image data export; its identity, lifetime and initialization remain unknown and it is not implemented.

### Functional

- [PKAlloc](../../../core/libs/prx/libSceJxr/src/Allocation.cpp): console behavior and ABI remain unverified. The implementation follows pinned jxrlib [JXRGlue.c](https://github.com/4creators/jxrlib/blob/f7521879862b9085318e814c6157490dd9dbbdb4/jxrgluelib/JXRGlue.c#L46-L50), using guest `calloc(1, cb)` so allocations match the guest heap released by `PKFree`. It stores the allocation, including null on failure, and returns `WMP_errSuccess` (0) or `WMP_errOutOfMemory` (-101) as a 64-bit `ERR`. A null `ppv` throws instead of the upstream null dereference; zero size follows guest `calloc`.

- [PixelFormatLookup](../../../core/libs/prx/libSceJxr/src/PixelFormatLookup.cpp) uses pinned public jxrlib through a C bridge and a 56-byte LP64 guest record. [BunnyFl reports firmware 13.42 native-PC comparisons](https://github.com/boykopovar/AnyPS5/pull/9954#issuecomment-6406356097): the 68 table entries match public jxrlib, and return values/record fields match across 802 cases repeated three times, except that the module clears padding bytes 28..31 on all 309 successes. This bridge now clears that four-byte range explicitly on success; it does not copy indeterminate C++ padding. This is attributed single-firmware evidence, not an author-run console measurement or proof of the complete Sony ABI/configuration. Module/library versions, other firmware and valid-mode null arguments remain unverified. Modes 0/1 perform forward GUID/reverse TIFF lookup; other modes and misses leave the entire record unchanged. Valid-mode null records and forward null GUIDs remain explicitly unsupported. Success borrows a read-only static GUID while the module is loaded; callers must not free it. Closes when: remaining Sony ABI, version/configuration and invalid-argument behavior are verified by attributable measurements or disassembly

- [PKFree](../../../core/libs/prx/libSceJxr/Export.cpp) (libSceJxr) follows Microsoft's jxrlib [JXRGlue.c](https://github.com/4creators/jxrlib/blob/f7521879862b9085318e814c6157490dd9dbbdb4/jxrgluelib/JXRGlue.c#L53-L62), whose four exported names the module shares: a non-null `ppv` has `*ppv` released with the guest `free` and set to null, and the result is always `WMP_errSuccess` (0) as a 64-bit `ERR` (`long`). That the console's module is built from jxrlib, and that its `PKFree` releases through libc's `free`, is inferred from the export names and not checked against the console's code. Closes when: the console's `PKFree` is disassembled or measured on a PS5

- [WMPAlloc, WMPFree and the memory stream](../../../core/libs/prx/libSceJxr/Export.cpp) (`CreateWS_Memory`, `EOSWS_Memory`, `ReadWS_Memory`, `WriteWS_Memory`, `SetPosWS_Memory`, `GetPosWS_Memory`): console code and layouts are unverified. They follow pinned jxrlib [strcodec.c](https://github.com/4creators/jxrlib/blob/f7521879862b9085318e814c6157490dd9dbbdb4/image/sys/strcodec.c#L246-L447) on the LP64 `WMPStream` layout, allocating with guest `calloc(1, cb)` and `free`; that the module is built from jxrlib is inferred from the export names. The `Close` callback is jxrlib's `CloseWS_Memory`, which the export inventory lacks. Where jxrlib dereferences null, `std::invalid_argument` is thrown: a null `ppv`, stream or `poffPos`, and a null buffer when a read or write copies at least one byte. Closes when: the console's functions are disassembled or measured on a PS5

- [readIS and writeIS](../../../core/libs/prx/libSceJxr/Export.cpp) use the non-ARM, LP64 `BitIOInfo` and `WMPStream` ABI and packet algorithm from [Microsoft's JPEG XR reference implementation](https://github.com/4creators/jxrlib/blob/f7521879862b9085318e814c6157490dd9dbbdb4/image/sys/strcodec.c#L1090-L1177). Console structure layouts and execution remain unverified. Profiling callbacks are omitted as in the reference Unix build with `DISABLE_PERF_MEASUREMENT`; the codec argument is unused. Where the reference uses an invalid pointer, `std::invalid_argument` is thrown instead: a null bit state, stream or callback, a read-only read packet, and a null packet when a read copies its shadow or a successful write offsets it; a null packet still reaches the callback first. No codec is instantiated by these helpers; callers must supply the reference ring buffer and guest-ABI stream callbacks.

- [remapQP, formatQuantizer, getACPredMode and InitZigzagScan](../../../core/libs/prx/libSceJxr/src/Quantizer.cpp) call jxrlib's [strPredQuant.c](https://github.com/4creators/jxrlib/blob/f7521879862b9085318e814c6157490dd9dbbdb4/image/sys/strPredQuant.c#L79-L192), [strcodec.c](https://github.com/4creators/jxrlib/blob/f7521879862b9085318e814c6157490dd9dbbdb4/image/sys/strcodec.c#L861-L874) and [image.c](https://github.com/4creators/jxrlib/blob/f7521879862b9085318e814c6157490dd9dbbdb4/image/sys/image.c#L173-L183), built from `3rdparty/jxrlib`, on the caller's 20-byte quantizer, 1,160-byte macroblock and 704-byte coding context without `WMP_OPT_QT`. These prototypes and layouts are inferred from the export names. A null quantizer, quantizer table, used channel or macroblock, more than 16 channels, and a scaled shift that takes the QP outside 32 bits throw. Closes when: the console's functions are disassembled or measured on a PS5

- The 119 additional exports in [Export.cpp](../../../core/libs/prx/libSceJxr/Export.cpp) are present in the pinned firmware 13.60 `libSceJxr` export inventory. Their parameter lists, return types and behavior are unverified. Parameterless `int` declarations are import-resolution placeholders, not verified ABI prototypes; every entry throws through `NotImplemented_nid_no_patch`. The `_nid_postfix` aliases keep the guest bindings distinct from private native helpers. No runtime functionality is implemented.