pokecrystal-board/engine/events/engine_flags.asm
mid-kid 0d9241889f Organize the engine/ directory, take 3
Renamed `title` to `movies`.
Moved some functions from `engine/routines/` to their fitting
directories, and cleaned up the base `engine/` directory.
Moved `engine/pokemon/tmhm.asm` back to `engine/items/`.

Made a new subdirectory:
* engine/tilesets: Contains all map-related graphics routines.
2018-03-25 16:18:33 +02:00

87 lines
1.1 KiB
NASM

EngineFlagAction:: ; 80430
; 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 0
jr z, .ceiling
jr c, .read ; cp 0 can't set carry!
jr .invalid
; There are only $a2 engine flags, so
; anything beyond that is invalid too.
.ceiling
ld a, e
cp 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
; 80462
INCLUDE "data/engine_flags.asm"