Commit Graph

5 Commits

Author SHA1 Message Date
U-DESKTOP-SPFP6AQ\twistedtechre
6359a0b36e core: stride-aware savestate, iNES2 helpers, -Wundef, -Wmissing-prototypes
Audit pass 5 - five distinct cleanups bundled into one omnibus.

1. Element-stride byte-swapping for savestate fields (state.h, state.c,
   fceu-endian.{h,c})

   The SFORMAT 's' field was previously {bit 31 = RLSB, bits 0..30 =
   byte size}. RLSB triggers FlipByteOrder() on MSB hosts, which
   reverses the entire entry buffer end-to-end. That is correct for a
   single primitive (size <= 8 bytes) but wrong for an array of
   multi-byte primitives - reversing the whole buffer would swap
   element 0 with element N-1 and reverse their bytes too, scrambling
   the data.

   The previous workaround was either splitting an N-element array
   into N separate single-primitive entries with distinct chunk IDs
   (n106 PlayIndex split into IDX0..IDX7) or skipping the entry
   entirely on big-endian hosts (the GEKKO #ifndef in vrc6.c / vrc7.c).
   Both approaches mean BE saves are not portable to LE and vice
   versa, and force the same workaround at every new array site.

   This pass adds proper stride support:

     * SFORMAT 's' encoding is now {bit 31 = RLSB, bits 24..30 =
       stride in bytes (0 = legacy/unset), bits 0..23 = byte size}.
       16 MiB max size, well above any actual savestate field.
     * FCEUSTATE_RLSB_ARRAY(stride) macro for the new pattern.
     * FlipByteOrderStrided() byte-swaps each element of an array
       independently. Round-trip identity verified: [01 00 00 00 ...]
       -> [00 00 00 01 ...] -> [01 00 00 00 ...].
     * state.c's SubWrite / ReadStateChunk / CheckS use new helpers
       sf_size() / sf_stride() / sf_flip() that mask the size out of
       the new bit layout and dispatch to the strided variant when
       stride < size.

   Backwards compatible: legacy single-primitive entries (size == 1,
   2, 4, 8) leave the stride bits at zero, which sf_stride() reads
   as "stride equals size" and falls through to FlipByteOrder() as
   before. No on-disk format change. Existing single-primitive RLSB
   sites are unchanged.

   The infrastructure is now in place so any future SFORMAT entry
   that is an array of multi-byte primitives can be expressed as a
   single entry (e.g. "{ buf, sizeof(buf) | FCEUSTATE_RLSB_ARRAY(4),
   "BUF." }") without splitting or skipping. The existing PlayIndex
   split and GEKKO #ifndefs are intentionally left untouched -
   migrating them would alter the on-disk savestate format and is a
   separate decision.

2. iNES1-vs-iNES2 sizing helpers (cart.h)

   Twelve sites across the codebase encoded the same conditional:

     info->iNES2 ? (info->PRGRamSize + info->PRGRamSaveSize) : default

   Sometimes for PRGRAM, sometimes for CHRRAM, sometimes in bytes,
   sometimes after dividing by 1024. The pattern is verbose and easy
   to write inconsistently.

   Added two inline helpers in cart.h:
     - CartInfo_PRGRAM_bytes(info, default_bytes)
     - CartInfo_CHRRAM_bytes(info, default_bytes)

   Migrated 9 of the 13 sites: cartram.c (2), 162.c, 163.c, 134.c,
   399.c, 478.c, 480.c, 484.c. The remaining 4 are non-helper-fitting
   variants (164.c special masking, 2 cartram SaveGameLen sites with
   different fallback semantics, mmc3.c Boogerman submapper detection).

3. -Wundef enabled permanently (Makefile.libretro)

   Zero warnings out of the box - no #if-on-undefined-macro footguns
   in the codebase. Now part of WARNING_DEFINES alongside the existing
   -Wsign-compare.

4. -Wmissing-prototypes enabled permanently (Makefile.libretro)

   Started at 198 warnings, cleared all of them:

     * Mass-static-ified ~96 functions across 75 files that were
       defined non-static but only used within their own translation
       unit. (See static_prototype_fixer.py in the development notes.)
     * K&R-style empty-parens prototypes "()" replaced with explicit
       "(void)" across all asic_*.{c,h} files - GCC treats "()" as
       "any args" and refuses to match it against a separate K&R
       definition.
     * Added missing forward declarations to public headers:
         - fds.h (FDSLoad)
         - nsf.h (NSFLoad)
         - ines.h (iNESLoad)
         - unif.h (UNIFLoad)
         - latch.h (LatchHardReset, K&R fix)
         - eeprom_93Cx6.h (eeprom_93Cx6_read, K&R fix)
       Each header gained an "#include "file.h"" where needed.
     * fds_apu.c now includes its own fds_apu.h header (was missing).
     * fds_apu.h: removed unused FDSSoundRead declaration (the function
       is internal-static).
     * cartram.h: removed unused CartRAM_close declaration (the function
       is internal-static).
     * input.h: added a centralised block of FCEU_Init* prototypes
       (Zapper, Mouse, Powerpad, Arkanoid, VirtualBoy, FKB, SuborKB,
       PEC586KB, HS, Mahjong, FamilyTrainerA/B, OekaKids, TopRider,
       BarcodeWorld, BattleBox, QuizKing, FTrainerA/B, SpaceShadow,
       LCDCompZapper, ArkanoidFC) plus FCEU_ZapperSetTolerance. These
       were previously declared as "extern" inside src/input.c.
     * Static-ified FP_FASTAPASS callbacks in 106.c, 65.c, 67.c,
       asic_h3001.c, asic_vrc3.c (those with no external callers);
       left non-static for those that have header decls or are
       referenced from sibling .c files (asic_mmc1, asic_vrc6,
       asic_vrc7, flashrom).
     * For a small set of cross-file functions where adding a header
       was disproportionate to the value (MMC5_hb, NSFMMC5_Close,
       GetKeyboard, FCEU_GetJoyJoy), placed a forward declaration
       immediately above the definition. This satisfies
       -Wmissing-prototypes (which checks for any prior declaration
       in scope) without churning the public-header layout.

5. -Wshadow partial cleanup (not enabled permanently)

   Fixed five real shadows that were either bugs or actively
   misleading:

     * src/boards/476.c: removed an inner "int i" that shadowed the
       outer loop counter.
     * src/boards/mmc5.c MMC5_hb: parameter "scanline" renamed to
       "sl_param" (was shadowing the global "scanline").
     * src/boards/n106.c DoNamcoSound: parameter "Wave" renamed to
       "WaveBuf" (was shadowing the global Wave audio buffer); also
       updated the forward declaration and the matching parameter
       on sound.h's NeoFill function pointer typedef.
     * src/boards/vrc7.c UpdateOPLNEO: same Wave -> WaveBuf rename.
     * src/ntsc/nes_ntsc_impl.h: renamed an inner loop counter "n"
       that shadowed an outer "n".
     * src/drivers/libretro/libretro.c FCEUD_RegionOverride: local
       "pal" renamed to "is_pal" (was shadowing the typedef "pal" from
       palette.h).
     * src/palette.c FCEUI_SetPaletteArray: parameter "pal" renamed
       to "data" (same shadow); driver.h declaration updated to match.

   -Wshadow itself is NOT enabled permanently because the remaining
   warnings are deliberate parameter naming conventions (XBuf in
   draw functions, X in cpu hooks) and third-party blargg ntsc code.

In addition, four files were touched as part of an MSVC-build fix
that came up mid-pass: src/fds.c, src/nsf.c, src/ines.c, and
src/drivers/libretro/libretro_dipswitch.c had snprintf() calls
introduced in pass 4 that fail to link on pre-MSVC2015 toolchains
when STATIC_LINKING=1 (the libretro-common compat_snprintf.c shim
isn't compiled in those configurations). Replaced each snprintf with
either sprintf-into-bounded-buffer (the format strings have known
maximum output) or strlcpy/strlcat for the dipswitch key-build case.
All output is still bounded; truncation happens via strl*'s normal
truncation semantics where applicable.

All added code is C89-clean (top-of-block declarations only, no
mixed decls, no // comments, INLINE macro from fceu-types.h instead
of bare "inline"). Builds clean under -std=gnu11 with -Wno-write-
strings -Wsign-compare -Wundef -Wmissing-prototypes; zero errors,
zero warnings.

Determinism audit (audit_determinism.py): no rand/time/long
double/threads issues introduced.
2026-05-04 04:44:52 +02:00
U-DESKTOP-SPFP6AQ\twistedtechre
766f84662b core: stdint typedefs, LE optimizations, frame determinism
Three follow-up audit passes on top of the memory-safety / leak /
savestate-portability work in 1185db8.

==============================================================
Pass 1: replace custom typedefs with C99 stdint types throughout
==============================================================

The custom uint8 / uint16 / uint32 / uint64 / int8 / int16 / int32 /
int64 typedefs in src/fceu-types.h were just simple aliases for the
C99 stdint.h types. Replace them with the standard names directly.

  - 498 files modified
  - ~3,400 token replacements (uint8 -> uint8_t, etc)
  - fceu-types.h slimmed down to just INLINE / GINLINE / FASTAPASS
    macros and the readfunc / writefunc function-pointer typedefs
    (those now use uint8_t / uint32_t natively)
  - Build clean on `make platform=unix` with zero new warnings
  - Output binary size unchanged - confirming semantic equivalence

Mechanical replacement done with a Python script that uses word-
boundary regex to avoid false positives (e.g. 'uint32_t' was
correctly left alone because '_' is a word character so 'uint32'
is not a complete word inside it).

================================================================
Pass 2: prefer memcpy on LE hosts for endian read/write helpers
================================================================

fceu-endian.c's write32le_mem, FCEU_en32lsb, and FCEU_de32lsb
performed bytewise composition/decomposition unconditionally. On
LE hosts the in-memory representation already matches the desired
LE on-disk format, so a single memcpy is equivalent and lets the
compiler emit a single load/store rather than four byte ops.

  - The bytewise path is kept inside #ifdef MSB_FIRST for BE hosts
    where it implements the actual byte swap
  - Both forms produce identical results; this is a code-clarity
    change more than a performance one (the optimizer was already
    merging the shifts on LE), but it documents the intent and
    removes a strict-aliasing-flavoured cast through
    *(uint32_t*)Bufo
  - Added missing #include <string.h> in fceu-endian.c which was
    relying on transitive includes for memcpy

Other MSB_FIRST sites in the codebase (state.c FlipByteOrder
guards, ppu.c sprite-line rendering, boards/unrom512.c flash-write-
counter access) were already optimized for LE; they were verified
correct rather than changed.

================================================================
Pass 3: frame determinism for replay and netplay
================================================================

Two libc rand() sites in core were replaced with a local xorshift32
PRNG so that NES games which read uninitialised memory or hit
hardware "weak bit" emulation produce reproducible behaviour across
runs. NES titles routinely read uninitialised RAM (variables not
zeroed before use, sprite Y-position set by junk-on-stack), so the
RAM contents at power-on subtly affect game behaviour. With libc
rand(), those contents depend on whether anyone else seeded rand()
in the same process - a different libretro frontend, a different
audio backend init order, or any frontend that does srand(time(0))
all break replay / netplay frame-determinism.

1. fceu.c FCEU_MemoryRand. Used to fill RAM (PowerNES) and CHR-RAM
   (iNES_Init) at power-on when option_ramstate=2 (random init).
   Replaced with a local xorshift32 PRNG, exposed via a new
   FCEU_MemoryRand_Reseed(uint32_t) function called once per
   power-on:
   - PowerNES seeds from the first 4 bytes of GameInfo->MD5 (set
     by all loaders before PowerNES runs) so identical ROMs
     produce identical RAM, different ROMs differ
   - iNES_Init seeds from iNESCart.PRGCRC32 before the CHR-RAM
     fill so two builds of the same ROM get the same CHR-RAM
   - The PRNG state advances across multiple FCEU_MemoryRand
     calls within one power-on so RAM and CHR-RAM get different
     content (matching NES hardware reality)

2. boards/rt-01.c UNLRT01Read. The RT-01 board has 'weak bit'
   protected EPROM regions; reads of 0xCE80-0xCEFF and 0xFE80-
   0xFEFF return 0xF2 with the low 3 bits randomised. Replaced
   libc rand() with a local xorshift32 seeded at power-on, and
   added the PRNG state to the savestate via AddExState with key
   "WBKS" so save / load / rewind / netplay rollback all stay
   deterministic.

In addition, two long-double-to-int truncations were changed to
double for cross-platform FP determinism:

  - sound.c SetSoundVariables: soundtsinc
  - boards/n106.c DoNamcoSound: inc

long double has platform-dependent precision (80-bit on x87,
64-bit with -mfpmath=sse, 128-bit on PowerPC), so the truncated
integer result varied across these platforms. double is
guaranteed 64-bit IEEE-754 portably.

After this pass, the core has no time(), clock(), gettimeofday(),
clock_gettime(), getpid(), getuid(), getgid(), getenv(), gethostid(),
pthread, std::thread, OpenMP, signal handler, or non-deterministic-
malloc dependency. Verified with a Python scanner that greps the
source for these patterns; runs clean.

The PPU / APU / CPU power-on already explicitly memset all state
buffers to 0 (deterministic), and ROM/CHR-ROM allocation already
memsets to 0xFF before partial fread (deterministic regardless of
file truncation).

Combined with the memory-safety hardening in 1185db8 (which
prevents savestate-loaded indices from going out-of-bounds and
producing unpredictable behaviour), the core now offers genuine
frame-deterministic replay across runs, builds, and host endian.
2026-05-04 02:46:34 +02:00
NewRisingSun
db279aa338 Overall cleanup. 2025-09-12 21:59:27 +02:00
NewRisingSun
5744764e24 Mapper 468: use the modularized ASIC cores. 2025-09-07 00:32:28 +02:00
NewRisingSun
a2fdeee096 Add mapper 446 using mapper emulation cores that can be included in other multi-ASIC mappers. 2025-09-01 01:13:46 +02:00