[Danigamer05]

What

Export six std::__sce_v2 Dinkumware binary scaling helpers from libc:

Export	NID	Original RVA
_ZNSt8__sce_v27_DscaleEPdl	gRj52WoTf5Q	0xCB330
_ZNSt8__sce_v28_FDscaleEPfl	wYwj23xDzPQ	0xCF0F0
_ZNSt8__sce_v28_LDscaleEPel	+AqTGiV4vBA	0x10D2D0
_ZNSt8__sce_v29_DunscaleEPsPd	1Vlo0OcN+sk	0xCA210
_ZNSt8__sce_v210_FDunscaleEPsPf	r8xEVOsN728	0xCA0C0
_ZNSt8__sce_v210_LDunscaleEPsPe	iAKatJKy6QY	0xCA200

The behavior comes from the libc.prx bundled with PPSA03671 v01.001.005 (J03848509, SHA-256 483961e086b8a1fffa8138b3c0badf798987fb5f35ec908d828946408be2d8a6).

That module computes these helpers on the exponent and fraction bits:

• NaN and infinity return their codes unchanged.
• Subnormal inputs are normalized first.
• _Dscale rounds a result that becomes subnormal to nearest even, returns an infinity on overflow and a signed zero on underflow.
• _Dunscale returns the significand in [1/2, 1) and its exponent.
• None of them sets errno or a floating-point exception flag.

The new ScaleFieldBits and UnscaleFieldBits in MathExact.cpp do the same with integer operations. The unversioned _Dscale and _Dunscale already here give the same values and codes for these inputs. They use host ldexp and frexp, which raise the denormal, underflow, overflow, inexact or invalid flags that the original never raises, so the versioned exports do not forward to them. As in the original, whose _LDscale and _LDunscale call the double forms, the __sce_v2 long double forms take an 8-byte double.

Tested

Windows x86-64, WinLibs GCC 15.2.0, Release, BUILD_TESTING=ON, main 5e85609d0b0152d14ae34d708d3237005ed311ca. Exact tested commit: 1c5093f845ed7ec88cd5533cb14c86fdc8cf182f.

The change was first tested on main 52e9ae6d57f37200c6b27234efb226b45d754528 at ef367efd7b803f96dfa7e8be523480663de73e0b, including the negative control below, then rebased onto the main above without conflicts; the diff of the change is the same apart from context lines. All four selected CTests and all 35,144,604 side-by-side vectors were run again at the tested commit and pass.

• Built libc, libkernel, their NID-patched production libraries and the guest_sce_v2_binary_scaling, guest_math_exact and guest_dinkumware_float_bits tests. All three pass, as does public_headers.

• The new test checks 112 double and 96 float scaling cases and 42 unscaling cases, the long double forms included. Inputs are zeros, subnormals, extremes, NaN and infinity, and exponents include the int64 limits. Every expected code, exponent and output was taken from the original module, not from this implementation.

• The original functions were loaded from the bundled module with its relocations applied. Its __error import was bound to this libc and __stack_chk_guard to a local value; every other import would have stopped the run, and none was called. MXCSR was reset to 0x1F80 and the x87 unit reinitialized before every call. The originals then ran side by side with the patched production library, called by NID, on 35,144,604 vectors:

  • special values, every binary exponent from -1100 to 1100 and random bit patterns;
  • exponents from the int64 minimum to its maximum;
  • 720,384 constructed cases at each rounding position, with results that tie, fall just below or above a tie, or carry into the smallest normal.

  Return code, output bits, exponent, errno, the full MXCSR and the x87 control and status words agree for all six exports.

• Negative control, at the pre-rebase commit: two lines were temporarily altered. Rounding ties were taken upward, and the unscaled exponent was shifted by one. The new CTest failed, and the side-by-side run flagged all six exports and both tie sets. The source was then restored byte for byte (SHA-256 checked) and rebuilt, and all four tests and all 35,144,604 vectors passed again.

• Code conventions and git diff --check pass.

• tools/pr_overlap.py read 1,748 open PRs at the tested commit and reports no confirmed overlap. An earlier placement of the CTest registration conflicted with test(libc): tokenize guarded buffers with high-byte delimiters #12887; it was moved before the rebase. It keeps exit 2 for 58 branches that already conflict with main (feat(aot): consolidate native ARM64 compiler, runtime and consumers #5021, fix(libc): follow measured wide printf behavior #5303, feat(libc): answer every libunwind cursor slot of an unwind context #6819, fix(libs): share Sony CRT handler and lconv state between libc and libSceAmpr #7081, feat(libc): scan 16-bit wide conversions on Linux #7386, feat(libc): support archive-backed stdio reads #7447, fix(libc): provide ASOBI_ROOT environment variable for title path resolution #7715, fix(libc): support character reads from random device streams #8150, fix(libc): use the Annex K size limit and codes of the PS5 libc, as measured on a PS5 #8965, fix(libc): follow snprintf_s and sscanf_s constraints as measured on a PS5 #9087, feat(libc): decode non-ASCII scanset members and non-BMP characters in the guest wide scanf #9340, fix(libc): follow a Windows symbolic link before .. in a guest path #9371, feat(libc): add the std::__sce_v2 thread start, timed wait, clock and processor count calls #9447, feat(libc): add std::__sce_v2::_Random_device, _Fiopen and setw #9526, fix(libc): restore syslog program-name fallback #9929, fix(libc): compute expf with FreeBSD msun's algorithm, as titles' libc.prx does #10113, fix(libc): compute erff and erfcf with fdlibm's algorithm, as titles' libc.prx does #10226, fix(libc): compute log with FreeBSD msun's algorithm, as titles' libc.prx does #10245, fix(libc): compute sin, cos and tan with FreeBSD msun's algorithm, as titles' libc.prx does #10250, fix(libc): compute asin and acos with FreeBSD msun's algorithm, as titles' libc.prx does #10253, fix(libc): compute pow with fdlibm's algorithm, as titles' libc.prx does #10265, fix(libc): compute exp2 with FreeBSD msun's algorithm, as titles' libc.prx does #10274, fix(libc): compute hypot with FreeBSD msun's algorithm, as titles' libc.prx does #10325, fix(libc): compute hypotf with FreeBSD msun's algorithm, as titles' libc.prx does #10328, fix(libc): set EDOM in fmod and fmodf where titles' libc.prx does #10345, fix(libc): compute remainder and remquo with fprem1, as titles' libc.prx does #10349, fix(libc): share multibyte state in fgetwc #10405, fix(libc): preserve tanh saturation flags and directed rounding #10506, fix(libc): preserve expm1 overflow rounding and exception flags #10510, fix(libc): preserve log1p pole and domain exception flags #10512, fix(libc): preserve atanh pole and domain exception flags #10565, fix(libc): convert Windows time zone names to UTF-8 #10987, fix(libc): compute acosl with FreeBSD msun's ld80 code as the bundled libc.prx does #11260, fix(libc): compute atanl with FreeBSD msun's ld80 code as the bundled libc.prx does #11262, fix(libc): compute exp2l with FreeBSD msun's ld80 code as the bundled libc.prx does #11266, fix(libc): bound narrow formatting fields #11332, fix(libc): compute cbrtl with FreeBSD msun's ld80 code as the bundled libc.prx does #11632, fix(libc): compute hypotl with FreeBSD msun's ld80 code as the bundled libc.prx does #11634, feat(libc): read 16-bit wide fields in fscanf on Linux #11724, feat(libc): accept positional arguments with wide scanf fields on Linux #11726, feat(libc): implement fcloseall with tracked stream lifetimes #11831, fix(libc): print unknown printf conversions and ' as titles' libc.prx does #11907, fix(libc): compute cosh with fdlibm's algorithm, as titles' libc.prx does #12122, fix(libc): print %C, %S and a zero %lc in the printf families as titles' libc.prx does #12397, fix(libc): read swscanf floating fields as titles' libc.prx does #12514, fix(libkernel): preserve DOS device names and trailing dots or spaces on Windows #12560, fix(libc): check asctime_s and ctime_s arguments as titles' libc.prx does #12574, fix(libc): report null gmtime_s and localtime_s arguments to the constraint handler #12593, fix(libc): check sprintf_s and vsprintf_s as titles' libc.prx does #12622, fix(libc): check swprintf_s and snwprintf_s as titles' libc.prx does #12627, feat(libkernel): cancel blocked POSIX reads with owned operations #12682, fix(libkernel): preserve blocking sockets over nonblocking native transport #12688, feat(libkernel): cancel blocked POSIX writes with partial progress #12700, feat(libkernel): support deferred cancellation in POSIX accept #12965, fix(libc): retain ordinary short character scan fields #13119, fix(libc): keep host logging on the console when a guest reopens stdout or stderr #13390, fix(libc): return EFAULT from getifaddrs for an unwritable list store #13804, docs(debt): separate entries with blank lines and drop derived export totals #14212). None of their added lines against their merge base contains the six names or NIDs. Merging each with this branch and with main using git merge-tree gives the same conflict blocks, and no conflict block contains this change.

Not tested: Linux, macOS, another SDK, a game, GPU or console. No game compatibility claim. No original module, extracted bytes, oracle or log is committed or uploaded.

Checklist

• Based on current main; no other open PR implements the same functions
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw (NotImplemented_nid_no_patch); silent stubs are listed under Silent stubs in their library's technical debt file
• No notes, investigation .md files or images added to the repository (attach them to this PR)
• New third-party code is a submodule built from source
• Generic behaviour, not specific to one title
• Depends on: none
• Fixes: none
• Unblocks: none
• GPUs tested: n/a
• AI-assisted: yes

🤖 Generated with Claude Code

[github-actions]

Progress report (1d91f29 → 1c5093f)

📈 System libraries: 26.64% (+0.01%, +6 implemented functions)

✅ 6 implemented

Library	Name
libc	_ZNSt8__sce_v210_FDunscaleEPsPf_nid_postfix
libc	_ZNSt8__sce_v210_LDunscaleEPsPe_nid_postfix
libc	_ZNSt8__sce_v27_DscaleEPdl_nid_postfix
libc	_ZNSt8__sce_v28_FDscaleEPfl_nid_postfix
libc	_ZNSt8__sce_v28_LDscaleEPel_nid_postfix
libc	_ZNSt8__sce_v29_DunscaleEPsPd_nid_postfix

Changed libraries (implemented exports)

Library	Before	After	Change
libc	1533/1548 (99.03%)	1539/1554 (99.03%)	+0.0037%

[github-actions]

Some comparisons could not be completed because a pull request conflicts with the base branch. Review these shared files manually before concluding that there is no overlap.

Pull request	Shared files not compared
PR 5021	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md
PR 5303	docs/dev/debt/libc.md
PR 6819	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md
PR 7081	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md
PR 7386	docs/dev/debt/libc.md
PR 7447	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md
PR 7715	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md
PR 8150	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md
PR 8965	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md
PR 9340	docs/dev/debt/libc.md
PR 9371	docs/dev/debt/libc.md
PR 9447	docs/dev/debt/libc.md
PR 9526	docs/dev/debt/libc.md
PR 9929	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md
PR 10113	docs/dev/debt/libc.md
PR 10226	docs/dev/debt/libc.md
PR 10245	docs/dev/debt/libc.md
PR 10250	docs/dev/debt/libc.md
PR 10253	docs/dev/debt/libc.md
PR 10265	docs/dev/debt/libc.md
PR 10274	docs/dev/debt/libc.md
PR 10325	docs/dev/debt/libc.md
PR 10328	docs/dev/debt/libc.md
PR 10345	docs/dev/debt/libc.md
PR 10349	docs/dev/debt/libc.md
PR 10405	docs/dev/debt/libc.md
PR 10506	docs/dev/debt/libc.md
PR 10510	docs/dev/debt/libc.md
PR 10512	docs/dev/debt/libc.md
PR 10565	docs/dev/debt/libc.md
PR 10987	docs/dev/debt/libc.md
PR 11260	docs/dev/debt/libc.md
PR 11262	docs/dev/debt/libc.md
PR 11266	docs/dev/debt/libc.md
PR 11332	docs/dev/debt/libc.md
PR 11632	docs/dev/debt/libc.md
PR 11634	docs/dev/debt/libc.md
PR 11724	docs/dev/debt/libc.md
PR 11726	docs/dev/debt/libc.md
PR 11831	core/libs/prx/libc/CMakeLists.txt core/libs/prx/libc/include/Api.hpp docs/dev/debt/libc.md
PR 11907	docs/dev/debt/libc.md
PR 12122	docs/dev/debt/libc.md
PR 12397	docs/dev/debt/libc.md
PR 12514	docs/dev/debt/libc.md
PR 12560	docs/dev/debt/libc.md
PR 12574	docs/dev/debt/libc.md
PR 12593	docs/dev/debt/libc.md
PR 12622	docs/dev/debt/libc.md
PR 12627	docs/dev/debt/libc.md
PR 12682	core/libs/prx/libc/CMakeLists.txt core/libs/prx/libc/include/Api.hpp docs/dev/debt/libc.md
PR 12688	core/libs/prx/libc/CMakeLists.txt core/libs/prx/libc/include/Api.hpp docs/dev/debt/libc.md
PR 12700	core/libs/prx/libc/CMakeLists.txt core/libs/prx/libc/include/Api.hpp docs/dev/debt/libc.md
PR 12965	core/libs/prx/libc/CMakeLists.txt core/libs/prx/libc/include/Api.hpp docs/dev/debt/libc.md
PR 13119	docs/dev/debt/libc.md
PR 13390	core/libs/prx/libc/CMakeLists.txt docs/dev/debt/libc.md
PR 13804	docs/dev/debt/libc.md
PR 14212	docs/dev/debt/libc.md
PR 14585	core/libs/prx/libc/CMakeLists.txt core/libs/prx/libc/include/Api.hpp docs/dev/debt/libc.md
PR 14610	core/libs/prx/libc/include/Api.hpp docs/dev/debt/libc.md

[BunnyFl]

Cross-checked against firmware 13.42's system libSceLibcInternal.sprx (sha256 a01795ab49df639dd40abd6194956ada062244826824ce486c9acab227bf5285) as well as the title's bundled libc.prx. Read from disassembly only, not measured on a console:

• All six NIDs are exported there.
• _LDscale (0x11e100) is call 0xdc480, the versioned _Dscale.
• _LDunscale (0xdb350) is call 0xdb360, the versioned _Dunscale.

So the 8-byte long double forwarding matches the system module too. I didn't re-run the flag and errno comparison against the system module.

Build and test on Windows (WinLibs GCC, BUILD_TESTING=ON), PR merged into current main: guest_sce_v2_binary_scaling and guest_math_exact pass. On main the exports don't exist, and the test doesn't link.