pokecrystal-board/home/math.asm

59 lines
716 B
NASM

SimpleMultiply::
; 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
SimpleDivide::
; 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
Multiply::
; Multiply hMultiplicand (3 bytes) by hMultiplier. Result in hProduct.
; All values are big endian.
push hl
push bc
callfar _Multiply
pop bc
pop hl
ret
Divide::
; Divide hDividend length b (max 4 bytes) by hDivisor. Result in hQuotient.
; All values are big endian.
push hl
push de
push bc
homecall _Divide
pop bc
pop de
pop hl
ret
SubtractAbsolute:: ; unreferenced
; Return |a - b|, sign in carry.
sub b
ret nc
cpl
add 1
scf
ret