AnyPS5/docs/dev/debt/libSceIcu.md

# libSceIcu technical debt

### Unknown function info

- [ICU export availability](../../../core/libs/prx/libSceIcu/Unescape.cpp) across firmware versions remains unproven. The [PS5 3.20 inventory](https://github.com/DNNDHH/PS5-3.20_Libs/blob/b2a77c09cd71c01f34c790cfbe98c751a13262ad/libSceIcu.c) includes the implemented escape, invariant-character and version helpers. [BunnyFl’s firmware 13.42 report](https://github.com/boykopovar/AnyPS5/pull/10961#issuecomment-6400071863) records `u_getVersion` returning `78.1.0.0` under an emulator, but neither escape function is in the checked native `system_ex/common_ex/lib/libSceIcu.sprx` export table. Only 104 of the 661 inventory NIDs appear among that module’s 299 exports. The exports for compatibility with older firmware are retained; availability and routing across firmware versions remain unproven.

### Functional

- [Space classification](../../../core/libs/prx/libSceIcu/Space.cpp) is unverified on a console. `u_isspace`, `u_isblank`, `u_isWhitespace`, `u_isJavaSpaceChar` and `u_isUWhiteSpace` follow ICU 78.1 [uchar.cpp](https://github.com/unicode-org/icu/blob/049e0d6a420629ac7db77256987d083a563287b5/icu4c/source/common/uchar.cpp#L196-L244) over fixed Zs, Zl, Zp and White_Space sets instead of ICU's property data; the sets are unchanged from ICU 65.1 to 78.1. Firmware 13.42 exports `u_isUWhiteSpace` but not the other four ([#11013](https://github.com/boykopovar/AnyPS5/pull/11013#issuecomment-6401310351)), which are kept from the 3.20 inventory for older firmware (see ICU export availability). Closes when: compared with the console.

- [C string helpers](../../../core/libs/prx/libSceIcu/CString.cpp) have no console ABI or behavior verification. Their names/NIDs are in the PS5 3.20 inventory; signatures and behavior follow ICU 78.1's [cstring.cpp](https://github.com/unicode-org/icu/blob/049e0d6a420629ac7db77256987d083a563287b5/icu4c/source/common/cstring.cpp), unchanged since 65.1 apart from casts. Formatting accepts radices 2–16; null buffers or other radices throw an invalid-argument exception, whereas ICU dereferences the buffer and only asserts the radix. Signed minima and outputs exceeding ICU's 30-byte temporary use unsigned arithmetic and caller storage without reproducing upstream undefined behavior. Parsing uses guest LP64 `strtoul` and keeps the low 32 bits; a null source throws. Cross-firmware availability, native invalid-input behavior and the undefined upstream cases remain unverified.

- [Converter STOP/SKIP callbacks](../../../core/libs/prx/libSceIcu/ConverterCallbacks.cpp) have no console ABI or behavior verification. Signatures and decisions follow ICU 78.1's [ucnv_err.h](https://github.com/unicode-org/icu/blob/049e0d6a420629ac7db77256987d083a563287b5/icu4c/source/common/unicode/ucnv_err.h) and [ucnv_err.cpp](https://github.com/unicode-org/icu/blob/049e0d6a420629ac7db77256987d083a563287b5/icu4c/source/common/ucnv_err.cpp). The callback-specific default-ignorable ranges include U+180F, which ICU 65.1 excludes; firmware-dependent selection is not implemented. Reasons outside the upstream enum's 0–7 value range and a null error pointer on a path that writes it throw `invalid_argument`; native behavior there is undefined. Untouched pointers remain unread, including the error pointer on no-write paths. Converter argument structures stay opaque because these callbacks do not access them; converter execution and other callbacks remain unavailable.

- [Escape decoding](../../../core/libs/prx/libSceIcu/Unescape.cpp) has no behavior or ABI verification on console hardware. It follows ICU 78.1's [ustring.cpp](https://github.com/unicode-org/icu/blob/049e0d6a420629ac7db77256987d083a563287b5/icu4c/source/common/ustring.cpp), including rejection of eight-digit braced hexadecimal escapes although its public header advertises up to eight digits. Null source or offset pointers and null callbacks with an in-range offset, which ICU dereferences, throw `std::invalid_argument`. A negative capacity writes nothing, as in ICU; source lengths exceeding `INT32_MAX` and a capacity that overflows ICU's signed `destCapacity - i` throw. Null-destination preflight ignores capacity. Closes when: compared with the console, including callback ABI, byte conversion, capacity limits and braced hexadecimal parsing.

- [Invariant character and version helpers](../../../core/libs/prx/libSceIcu/Version.cpp) are unverified on a console. `u_charsToUChars`, `u_UCharsToChars`, `u_versionFromString`, `u_versionFromUString` and `u_versionToString` follow ICU 78.1 [uinvchar.cpp](https://github.com/unicode-org/icu/blob/release-78.1/icu4c/source/common/uinvchar.cpp) and [putil.cpp](https://github.com/unicode-org/icu/blob/release-78.1/icu4c/source/common/putil.cpp), unchanged since 65.1. Firmware 13.42 reports ICU 78.1 and exports none of them ([#11013](https://github.com/boykopovar/AnyPS5/pull/11013#issuecomment-6400470698)); the [3.20 table](https://github.com/DNNDHH/PS5-3.20_Libs/blob/b2a77c09cd71c01f34c790cfbe98c751a13262ad/libSceIcu.c) has all five. Version parts use the guest `strtoul`, truncated to eight bits; `u_versionToString` keeps ICU's dropped zero tens digit (105 becomes `15`). A null buffer with a positive conversion length throws; ICU dereferences it. Closes when: compared with the console.

### Known export names; ABI prototypes unverified

- The 98 `sceIcuUnknown_*_nid_no_patch` exports in [Export.cpp](../../../core/libs/prx/libSceIcu/Export.cpp) are present in the PS5 3.20 export inventory from [PS5-3.20_Libs](https://github.com/DNNDHH/PS5-3.20_Libs). Their prototypes and behavior are unverified. Each uses the no-parameter import-resolution convention and throws through `NotImplemented_nid_no_patch`; these declarations make no ABI or behavior claim.