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|
GiveMoney::
ld a, 3
call AddMoney
ld bc, MaxMoney
ld a, 3
call CompareMoney
jr z, .not_maxed_out
jr c, .not_maxed_out
ld hl, MaxMoney
ld a, [hli]
ld [de], a
inc de
ld a, [hli]
ld [de], a
inc de
ld a, [hli]
ld [de], a
scf
ret
.not_maxed_out
and a
ret
MaxMoney:
dt MAX_MONEY
TakeMoney::
ld a, 3
call SubtractMoney
jr nc, .okay
; leave with 0 money
xor a
ld [de], a
inc de
ld [de], a
inc de
ld [de], a
scf
ret
.okay
and a
ret
CompareMoney::
ld a, 3
CompareFunds:
; a: number of bytes
; bc: start addr of amount (big-endian)
; de: start addr of account (big-endian)
push hl
push de
push bc
ld h, b
ld l, c
ld c, 0
ld b, a
.loop1
dec a
jr z, .done
inc de
inc hl
jr .loop1
.done
and a
.loop2
ld a, [de]
sbc [hl]
jr z, .okay
inc c
.okay
dec de
dec hl
dec b
jr nz, .loop2
jr c, .set_carry
ld a, c
and a
jr .skip_carry
.set_carry
ld a, 1
and a
scf
.skip_carry
pop bc
pop de
pop hl
ret
SubtractMoney:
ld a, 3
SubtractFunds:
; a: number of bytes
; bc: start addr of amount (big-endian)
; de: start addr of account (big-endian)
push hl
push de
push bc
ld h, b
ld l, c
ld b, a
ld c, 0
.loop
dec a
jr z, .done
inc de
inc hl
jr .loop
.done
and a
.loop2
ld a, [de]
sbc [hl]
ld [de], a
dec de
dec hl
dec b
jr nz, .loop2
pop bc
pop de
pop hl
ret
AddMoney:
ld a, 3
AddFunds:
; a: number of bytes
; bc: start addr of amount (big-endian)
; de: start addr of account (big-endian)
push hl
push de
push bc
ld h, b
ld l, c
ld b, a
.loop1
dec a
jr z, .done
inc de
inc hl
jr .loop1
.done
and a
.loop2
ld a, [de]
adc [hl]
ld [de], a
dec de
dec hl
dec b
jr nz, .loop2
pop bc
pop de
pop hl
ret
GiveCoins::
ld a, 2
ld de, wCoins
call AddFunds
ld a, 2
ld bc, .maxcoins
call CompareFunds
jr c, .not_maxed
ld hl, .maxcoins
ld a, [hli]
ld [de], a
inc de
ld a, [hli]
ld [de], a
scf
ret
.not_maxed
and a
ret
.maxcoins
bigdw MAX_COINS
TakeCoins::
ld a, 2
ld de, wCoins
call SubtractFunds
jr nc, .okay
; leave with 0 coins
xor a
ld [de], a
inc de
ld [de], a
scf
ret
.okay
and a
ret
CheckCoins::
ld a, 2
ld de, wCoins
jp CompareFunds
|
