Tanner Fokkens c0a30de0b2 Fix inc/dec clobbering carry flag, breaking Pokemon Crystal menus ...

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.

2026-02-06 17:11:15 -08:00

1.5 KiB

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