ref: 2b2c1ac64906ba61ab713d2e2462a2ca9fb8d05c
dir: /engine/events/engine_flags.asm/
EngineFlagAction:: ; Do action b on engine flag de ; ; b = 0: reset flag ; = 1: set flag ; > 1: check flag, result in c ; ; Setting/resetting does not return a result. ; 16-bit flag ids are considered invalid, but it's nice ; to know that the infrastructure is there. ld a, d cp HIGH(NUM_ENGINE_FLAGS) jr z, .ceiling jr c, .read ; cp 0 can't set carry! jr .invalid ; There are only NUM_ENGINE_FLAGS engine flags, so ; anything beyond that is invalid too. .ceiling ld a, e cp LOW(NUM_ENGINE_FLAGS) jr c, .read ; Invalid flags are treated as flag 00. .invalid xor a ld e, a ld d, a ; Get this flag's location. .read ld hl, EngineFlags ; location add hl, de add hl, de ; bit add hl, de ; location ld e, [hl] inc hl ld d, [hl] inc hl ; bit ld c, [hl] ; What are we doing with this flag? ld a, b cp 1 jr c, .reset ; b = 0 jr z, .set ; b = 1 ; Return the given flag in c. .check ld a, [de] and c ld c, a ret ; Set the given flag. .set ld a, [de] or c ld [de], a ret ; Reset the given flag. .reset ld a, c cpl ; AND all bits except the one in question ld c, a ld a, [de] and c ld [de], a ret INCLUDE "data/events/engine_flags.asm"