The GB inc/dec instructions must preserve the carry flag and only
modify Z. The JIT was capturing both Z and C from the 68k CCR,
causing dec to incorrectly set carry on borrow (e.g. 0-1=FF).
This broke Pokemon Crystal's xor_a_dec_a helper which returns with
C=0 to signal "no action". The corrupted C=1 caused the scrolling
menu to exit prematurely when pressing down past CANCEL, showing
phantom items and garbage prices.
Fix compile_set_z_flag to merge new Z with old C, and
compile_set_c_flag to merge new C with old Z. Move and/or/xor
immediates to compile_set_zc_flags since they should clear C.
- Add combined cgb_color_lut[16][4] to eliminate per-pixel conditional
branches and multiply operations in final draw functions
- Add tile_decode_cgb[256] LUT to replace 8-iteration bit extraction
loops with 2 table lookups
- Add dirty palette tracking (bg_palette_dirty, obj_palette_dirty) to
skip expensive Color2Index calls when palettes haven't changed
- Replace multiply-based pixel_shift calculation with 4-byte LUT
Also fixes test harness to initialize JIT_CTX_GB_SP for slow path
stack operations.
Major fixes:
- CALL, RET, RST, and their conditional variants now properly check
stack_in_ram before accessing memory via A3. Previously they assumed
A3 was always a valid native pointer, causing memory corruption when
in slow mode (A3 held raw GB SP value like 0xFFFE).
- Fixed initial SP setup to use fast mode with A3 pointing to actual
HRAM memory instead of holding the raw GB SP value.
- STOP instruction now calls runtime handler to check for CGB speed
switch instead of immediately halting. Enables double-speed mode.
- HDMA cancellation: writing to HDMA5 with bit 7=0 while HDMA is active
now cancels the transfer (fixes Pokemon Crystal).
Safety improvements:
- Added src_ptr bounds check to prevent m68k_offsets array overflow
- Added PC validation to reject execution in VRAM/external RAM
- Added PC history ring buffer for crash debugging
Tested: Klax, Link's Awakening DX, Wario Land 3 now boot successfully.
- Move DAA implementation to dedicated compile_daa() function
- Add 5 DAA tests covering addition/subtraction BCD adjustment
- Fix bug where CCR was clobbered after testing N flag
Tanner Fokkens
Matthew Laux