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; switch to rombank (a + top2 of h shifted down),
; set top2 of h to 01 (switchable ROM bank area),
; return old rombank id on top-of-stack
BankpushROM:
push hl
push bc
push af
push de
ld e, l
ld d, h
ld hl, sp+$9
ld b, [hl]
dec hl
ld c, [hl]
dec hl
ld [hl], b
dec hl
ld [hl], c
ld hl, sp+$9
ldh a, [hBankROM]
ld [hld], a
ld [hl], $0
ld a, d
rlca
rlca
and $3
ld b, a
res 7, d
set 6, d ; $4000 ≤ de ≤ $7fff
ld l, e
ld h, d
pop de
pop af
add b
call BankswitchROM
pop bc
ret
; switch to rombank a,
; return old rombank id on top-of-stack
BankpushROM2:
push hl
push bc
push af
push de
ld e, l
ld d, h
ld hl, sp+$9
ld b, [hl]
dec hl
ld c, [hl]
dec hl
ld [hl], b
dec hl
ld [hl], c
ld hl, sp+$9
ldh a, [hBankROM]
ld [hld], a
ld [hl], $0
ld l, e
ld h, d
pop de
pop af
call BankswitchROM
pop bc
ret
; restore rombank from top-of-stack
BankpopROM:
push hl
push de
ld hl, sp+$7
ld a, [hld]
call BankswitchROM
dec hl
ld d, [hl]
dec hl
ld e, [hl]
inc hl
inc hl
ld [hl], e
inc hl
ld [hl], d
pop de
pop hl
pop af
ret
; switch ROM bank to a
BankswitchROM:
ldh [hBankROM], a
ld [MBC3RomBank], a
ret
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