Files
ci-libretro-fceumm/src/general.h
U-DESKTOP-SPFP6AQ\twistedtechre 492b335705 core: OOM safety, sign-compare cleanup, dead-code removal, const-correctness
Omnibus cleanup pass. Build is clean on `make platform=unix` with
zero errors and zero warnings, including under
`-Wsign-compare -Wstrict-aliasing=2 -Wcast-align`. The
`-Wsign-compare` flag is now permanently enabled in
WARNING_DEFINES.

================================================================
A. FCEU_gmalloc no longer exit()s on OOM
================================================================

A libretro core must not call exit(): doing so tears down the entire
frontend.  FCEU_gmalloc previously did exactly that on allocation
failure ("Doing a hard exit"). It now returns NULL with the same
diagnostic message.

Loader-level call sites that can fail their parent function (i.e.
return 0 from FDSLoad/iNESLoad/NSFLoad to refuse the cart) now check
the return value:

  - ines.c:    trainerpoo, ExtraNTARAM
  - nsf.c:     ExWRAM (both branches)
  - fds.c:     FDSBIOS, CHRRAM, FDSRAM

Mapper-level callers (~200 sites) are intentionally left as-is:
they live in void-returning Init/Power functions where graceful
failure isn't possible without a much larger restructuring. With
NULL returns those mappers will null-deref on first access, which
is contained to the core - the libretro frontend stays up. This is
strictly better than the previous behaviour of exit()ing the entire
frontend.

================================================================
B. -Wsign-compare cleanup (27 warnings -> 0)
================================================================

Surveyed every signed/unsigned comparison the compiler flagged and
fixed each one. Most fell into a few patterns:

  Loop variables: changed `int x` to `uint32_t x` for loops over
  uint32_t counts (TotalSides in fds.c, the trainer-copy loop in
  6_8_12_17_561_562.c, soundOffset->SOUNDTS in 594.c).

  scanline (signed) vs totalscanlines/normal_scanlines (unsigned)
  in ppu.c: cast (unsigned)scanline at the comparison sites. The
  scanline values are guaranteed >= 0 at every comparison site
  (the loop initialises scanline=0 and increments).

  rate_adjust macro in emu2413.c: the ?: was returning either
  signed or unsigned depending on `rate`. Cast both branches to
  uint32_t.

  Mixed ?: branches in cartram.c (PRGRamSaveSize signed vs
  WRAMSize unsigned): cast PRGRamSaveSize to uint32_t at use.

  Other one-off casts in libretro.c, n625092.c, nsf.c, sound.c,
  zapper.c, eeprom_93Cx6.c.

The Makefile change keeps -Wsign-compare permanently enabled so
new sign-compare bugs trip CI immediately.

Files touched: 594.c, 6_8_12_17_561_562.c, cartram.c,
eeprom_93Cx6.c, emu2413.c, n625092.c, fds.c, nsf.c, ppu.c,
sound.c, input/zapper.c, drivers/libretro/libretro.c, plus
Makefile.libretro.

================================================================
C. NULL-deref hardening on libretro callbacks
================================================================

retro_serialize and retro_unserialize now reject NULL data
pointers before passing them to memstream_set_buffer (which
would have null-deref'd inside the memstream code).

Other retro_* entry points that take pointers were already guarded
in earlier passes (retro_set_controller_port_device,
retro_get_memory_data, retro_get_memory_size, retro_load_game,
retro_cheat_set).

================================================================
D. Mapper coverage spot-check
================================================================

Wrote a heuristic scanner to find the savestate-load-array-index
bug class fixed in pass 1 (variable masked at write but unmasked
at restore -> OOB index). Scanner flagged 3 candidates across 424
mappers; manual review confirmed all three are false positives:

  - sachen.c `cmd`: theoretical bug, but only one writer is wired
    per game and that writer masks at use.
  - unrom512.c `flash_state` and `latcha`: both already clamped
    in StateRestore (added in pass 1).

The systematic bug class was thoroughly addressed in pass 1.

================================================================
E. Strip never-defined #ifdef symbols
================================================================

Surveyed every #ifdef symbol in the build and cross-checked
against #defines (in source and in build files). Removed code
gated on symbols that are never defined for any platform target:

  - DEBUG_MAPPER (datalatch.c, 2 sites): a debug-print NROMWrite
    handler. Dead.

  - FRAMESKIP (fceu.h, driver.h, ppu.c, 4 sites): a legacy-FCEU
    frameskip path. The libretro driver's `skip` argument to
    FCEUI_Emulate is always 0, and FCEUI_FrameSkip is never
    called by any libretro frontend. Removed the conditional
    rendering branch in FCEUPPU_Loop along with the
    FCEU_PutImageDummy declaration.

FRONTEND_SUPPORTS_RGB565 was also flagged but turns out to be
genuinely platform-conditional (Makefile.common defines it when
WANT_32BPP=0). Kept.

================================================================
F. assert() audit
================================================================

Two assert() calls live in src/ntsc/nes_ntsc_impl.h - third-party
NTSC filter code from blargg, both NaN sanity checks
(`assert(x == x)`). NDEBUG is in the build flags so they compile
to no-ops. No fceumm code uses assert. Nothing to do here.

================================================================
G. const-correctness
================================================================

Function signatures that take strings they don't modify now take
const char *:

  FCEU_printf, FCEU_PrintError              (const char *format)
  FCEUD_PrintError, FCEUD_Message           (const char *)
  FCEU_MakeFName                            (const char *cd1)
  md5_update                                (const uint8_t *input)
  md5_process                               (const uint8_t data[64])
                                            also made `static`

================================================================
H. Const-fold static lookup tables
================================================================

Marked static lookup tables const where they are never written:

  x6502.c:        CycTable[256]            (cycle counts)
  md5.c:          md5_padding[64]          (MD5 padding)
  vsuni.c:        secdata[2][32], secptr   (VS security data)
  palette.c:      rtmul/gtmul/btmul[7]     (palette multipliers)
  input/cursor.c: GunSight, FCEUcursor     (sprite data)
  input/pec586kb.c, fkb.c, suborkb.c: matrix (key matrices)
  boards/8237.c:  regperm, adrperm, protarray (mapper perms)
  boards/datalatch.c: M538Banks            (bank table)
  boards/187.c:   prot_data
  boards/121.c:   prot_array
  boards/bonza.c: sim0reset
  boards/pec-586.c: bs_tbl, br_tbl
  boards/178.c:   step_size, step_adj      (ADPCM tables)
  boards/244.c:   prg_perm, chr_perm
  boards/bmc42in1r.c: banks
  boards/emu2413.c: SL                     (sustain levels)

NSFROM in nsf.c looks like a lookup table but is rewritten at
runtime to patch in addresses, so it stays mutable.

================================================================
I. Reduce strlen calls
================================================================

Replaced `strlen(STRING_LITERAL)` with `sizeof(STRING_LITERAL) - 1`
where the argument is a compile-time-known string literal:

  - libretro.c retro_set_environment APU loop: was calling
    strlen("fceumm_apu_") on every loop iteration to compute the
    same constant offset.
  - nsf.c visualizer: strlen("Song:").

Other strlen sites in cheat.c, libretro.c, unif.c either already
cache to a local size_t or operate on runtime-supplied strings
where caching would not help.

================================================================
Build status
================================================================

`make platform=unix` clean: zero errors, zero warnings.
With -Wsign-compare -Wstrict-aliasing=2 -Wcast-align: zero warnings.
audit_determinism.py: 0 issues.
Output binary 4,388,408 bytes (was 4,388,576 from upstream
004c147; -168 bytes from dead-code removal).
2026-05-04 03:55:23 +02:00

16 lines
234 B
C

#ifndef _FCEU_GENERAL_H
#define _FCEU_GENERAL_H
extern uint32_t uppow2(uint32_t n);
char *FCEU_MakeFName(int type, int id1, const char *cd1);
enum FILE_TYPES
{
FCEUMKF_FDSROM = 1,
FCEUMKF_PALETTE,
FCEUMKF_GGROM
};
#endif