ref: 3e72d0834efd0a02383fa4fd960ed8e563b0e8c4
dir: /engine/math/multiply_divide.asm/
_Multiply:: ld a, $8 ld b, a xor a ldh [hProduct], a ldh [hMultiplyBuffer], a ldh [hMultiplyBuffer+1], a ldh [hMultiplyBuffer+2], a ldh [hMultiplyBuffer+3], a .loop ldh a, [hMultiplier] srl a ldh [hMultiplier], a ; (aliases: hDivisor, hMultiplier, hPowerOf10) jr nc, .smallMultiplier ldh a, [hMultiplyBuffer+3] ld c, a ldh a, [hMultiplicand+2] add c ldh [hMultiplyBuffer+3], a ldh a, [hMultiplyBuffer+2] ld c, a ldh a, [hMultiplicand+1] adc c ldh [hMultiplyBuffer+2], a ldh a, [hMultiplyBuffer+1] ld c, a ldh a, [hMultiplicand] ; (aliases: hMultiplicand) adc c ldh [hMultiplyBuffer+1], a ldh a, [hMultiplyBuffer] ld c, a ldh a, [hProduct] ; (aliases: hProduct, hPastLeadingZeros, hQuotient) adc c ldh [hMultiplyBuffer], a .smallMultiplier dec b jr z, .done ldh a, [hMultiplicand+2] sla a ldh [hMultiplicand+2], a ldh a, [hMultiplicand+1] rl a ldh [hMultiplicand+1], a ldh a, [hMultiplicand] rl a ldh [hMultiplicand], a ldh a, [hProduct] rl a ldh [hProduct], a jr .loop .done ldh a, [hMultiplyBuffer+3] ldh [hProduct+3], a ldh a, [hMultiplyBuffer+2] ldh [hProduct+2], a ldh a, [hMultiplyBuffer+1] ldh [hProduct+1], a ldh a, [hMultiplyBuffer] ldh [hProduct], a ret _Divide:: xor a ldh [hDivideBuffer], a ldh [hDivideBuffer+1], a ldh [hDivideBuffer+2], a ldh [hDivideBuffer+3], a ldh [hDivideBuffer+4], a ld a, $9 ld e, a .loop ldh a, [hDivideBuffer] ld c, a ldh a, [hDividend+1] ; (aliases: hMultiplicand) sub c ld d, a ldh a, [hDivisor] ; (aliases: hDivisor, hMultiplier, hPowerOf10) ld c, a ldh a, [hDividend] ; (aliases: hProduct, hPastLeadingZeros, hQuotient) sbc c jr c, .next ldh [hDividend], a ; (aliases: hProduct, hPastLeadingZeros, hQuotient) ld a, d ldh [hDividend+1], a ; (aliases: hMultiplicand) ldh a, [hDivideBuffer+4] inc a ldh [hDivideBuffer+4], a jr .loop .next ld a, b cp $1 jr z, .done ldh a, [hDivideBuffer+4] sla a ldh [hDivideBuffer+4], a ldh a, [hDivideBuffer+3] rl a ldh [hDivideBuffer+3], a ldh a, [hDivideBuffer+2] rl a ldh [hDivideBuffer+2], a ldh a, [hDivideBuffer+1] rl a ldh [hDivideBuffer+1], a dec e jr nz, .next2 ld a, $8 ld e, a ldh a, [hDivideBuffer] ldh [hDivisor], a ; (aliases: hDivisor, hMultiplier, hPowerOf10) xor a ldh [hDivideBuffer], a ldh a, [hDividend+1] ; (aliases: hMultiplicand) ldh [hDividend], a ; (aliases: hProduct, hPastLeadingZeros, hQuotient) ldh a, [hDividend+2] ldh [hDividend+1], a ; (aliases: hMultiplicand) ldh a, [hDividend+3] ldh [hDividend+2], a .next2 ld a, e cp $1 jr nz, .okay dec b .okay ldh a, [hDivisor] ; (aliases: hDivisor, hMultiplier, hPowerOf10) srl a ldh [hDivisor], a ; (aliases: hDivisor, hMultiplier, hPowerOf10) ldh a, [hDivideBuffer] rr a ldh [hDivideBuffer], a jr .loop .done ldh a, [hDividend+1] ; (aliases: hMultiplicand) ldh [hRemainder], a ; (aliases: hDivisor, hMultiplier, hPowerOf10) ldh a, [hDivideBuffer+4] ldh [hQuotient+3], a ldh a, [hDivideBuffer+3] ldh [hQuotient+2], a ldh a, [hDivideBuffer+2] ldh [hQuotient+1], a ; (aliases: hMultiplicand) ldh a, [hDivideBuffer+1] ldh [hDividend], a ; (aliases: hProduct, hPastLeadingZeros, hQuotient) ret