diff options
Diffstat (limited to 'engine/multiply_divide.asm')
| -rwxr-xr-x | engine/multiply_divide.asm | 65 |
1 files changed, 33 insertions, 32 deletions
diff --git a/engine/multiply_divide.asm b/engine/multiply_divide.asm index 52e86b36..d664c9d4 100755 --- a/engine/multiply_divide.asm +++ b/engine/multiply_divide.asm @@ -7,11 +7,12 @@ _Multiply: ld [H_MULTIPLYBUFFER+1], a ld [H_MULTIPLYBUFFER+2], a ld [H_MULTIPLYBUFFER+3], a -.loop +.multiplyLoop ld a, [H_MULTIPLIER] srl a - ld [H_MULTIPLIER], a ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) - jr nc, .smallMultiplier + ld [H_MULTIPLIER], a + jr nc, .smallMultiplier ; less than $80 +; code to possibly multiply the multiplicand by 2 and divide the multiplier by 2? ld a, [H_MULTIPLYBUFFER+3] ld c, a ld a, [H_MULTIPLICAND+2] @@ -24,12 +25,12 @@ _Multiply: ld [H_MULTIPLYBUFFER+2], a ld a, [H_MULTIPLYBUFFER+1] ld c, a - ld a, [H_MULTIPLICAND] ; (aliases: H_MULTIPLICAND) + ld a, [H_MULTIPLICAND] adc c ld [H_MULTIPLYBUFFER+1], a ld a, [H_MULTIPLYBUFFER] ld c, a - ld a, [H_PRODUCT] ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) + ld a, [H_PRODUCT] adc c ld [H_MULTIPLYBUFFER], a .smallMultiplier @@ -47,7 +48,7 @@ _Multiply: ld a, [H_PRODUCT] rl a ld [H_PRODUCT], a - jr .loop + jr .multiplyLoop .done ld a, [H_MULTIPLYBUFFER+3] ld [H_PRODUCT+3], a @@ -68,28 +69,28 @@ _Divide: ld [H_DIVIDEBUFFER+4], a ld a, $9 ld e, a -.asm_37db3 +.asm_f6680 ld a, [H_DIVIDEBUFFER] ld c, a - ld a, [H_DIVIDEND+1] ; (aliases: H_MULTIPLICAND) + ld a, [H_DIVIDEND+1] sub c ld d, a - ld a, [H_DIVISOR] ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) + ld a, [H_DIVISOR] ld c, a - ld a, [H_DIVIDEND] ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) + ld a, [H_DIVIDEND] sbc c - jr c, .asm_37dce - ld [H_DIVIDEND], a ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) + jr c, .asm_f669b + ld [H_DIVIDEND], a ld a, d - ld [H_DIVIDEND+1], a ; (aliases: H_MULTIPLICAND) + ld [H_DIVIDEND+1], a ld a, [H_DIVIDEBUFFER+4] inc a ld [H_DIVIDEBUFFER+4], a - jr .asm_37db3 -.asm_37dce + jr .asm_f6680 +.asm_f669b ld a, b cp $1 - jr z, .asm_37e18 + jr z, .done ld a, [H_DIVIDEBUFFER+4] sla a ld [H_DIVIDEBUFFER+4], a @@ -103,41 +104,41 @@ _Divide: rl a ld [H_DIVIDEBUFFER+1], a dec e - jr nz, .asm_37e04 + jr nz, .asm_f66d1 ld a, $8 ld e, a ld a, [H_DIVIDEBUFFER] - ld [H_DIVISOR], a ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) + ld [H_DIVISOR], a xor a ld [H_DIVIDEBUFFER], a - ld a, [H_DIVIDEND+1] ; (aliases: H_MULTIPLICAND) - ld [H_DIVIDEND], a ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) + ld a, [H_DIVIDEND+1] + ld [H_DIVIDEND], a ld a, [H_DIVIDEND+2] - ld [H_DIVIDEND+1], a ; (aliases: H_MULTIPLICAND) + ld [H_DIVIDEND+1], a ld a, [H_DIVIDEND+3] ld [H_DIVIDEND+2], a -.asm_37e04 +.asm_f66d1 ld a, e cp $1 - jr nz, .asm_37e0a + jr nz, .asm_f66d7 dec b -.asm_37e0a - ld a, [H_DIVISOR] ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) +.asm_f66d7 + ld a, [H_DIVISOR] srl a - ld [H_DIVISOR], a ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) + ld [H_DIVISOR], a ld a, [H_DIVIDEBUFFER] rr a ld [H_DIVIDEBUFFER], a - jr .asm_37db3 -.asm_37e18 - ld a, [H_DIVIDEND+1] ; (aliases: H_MULTIPLICAND) - ld [H_REMAINDER], a ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) + jr .asm_f6680 +.done + ld a, [H_DIVIDEND+1] + ld [H_REMAINDER], a ld a, [H_DIVIDEBUFFER+4] ld [H_QUOTIENT+3], a ld a, [H_DIVIDEBUFFER+3] ld [H_QUOTIENT+2], a ld a, [H_DIVIDEBUFFER+2] - ld [H_QUOTIENT+1], a ; (aliases: H_MULTIPLICAND) + ld [H_QUOTIENT+1], a ld a, [H_DIVIDEBUFFER+1] - ld [H_DIVIDEND], a ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) + ld [H_QUOTIENT], a ret |