pokecrystal-board/common/math.asm

77 lines
852 B
NASM

SimpleMultiply: ; 3105
; Return a * c.
and a
ret z
push bc
ld b, a
xor a
.loop
add c
dec b
jr nz, .loop
pop bc
ret
; 3110
SimpleDivide: ; 3110
; Divide a by c. Return quotient b and remainder a.
ld b, 0
.loop
inc b
sub c
jr nc, .loop
dec b
add c
ret
; 3119
Multiply: ; 3119
; Multiply hMultiplicand (3 bytes) by hMultiplier. Result in hProduct.
; All values are big endian.
push hl
push bc
callab _Multiply
pop bc
pop hl
ret
; 3124
Divide: ; 3124
; Divide hDividend length b (max 4 bytes) by hDivisor. Result in hQuotient.
; All values are big endian.
push hl
push de
push bc
ld a, [hROMBank]
push af
ld a, BANK(_Divide)
rst Bankswitch
call _Divide
pop af
rst Bankswitch
pop bc
pop de
pop hl
ret
; 3136
SubtractSigned: ; 3136
; Return a - b, sign in carry.
sub b
ret nc
cpl
add 1
scf
ret
; 313d