diff options
Diffstat (limited to 'engine/multiply_divide.asm')
| -rwxr-xr-x | engine/multiply_divide.asm | 111 |
1 files changed, 56 insertions, 55 deletions
diff --git a/engine/multiply_divide.asm b/engine/multiply_divide.asm index 52e86b36..2bc26de2 100755 --- a/engine/multiply_divide.asm +++ b/engine/multiply_divide.asm @@ -2,16 +2,17 @@ _Multiply: ld a, $8 ld b, a xor a - ld [H_PRODUCT], a - ld [H_MULTIPLYBUFFER], a - ld [H_MULTIPLYBUFFER+1], a - ld [H_MULTIPLYBUFFER+2], a - ld [H_MULTIPLYBUFFER+3], a -.loop - ld a, [H_MULTIPLIER] + ld [H_PRODUCT], a ; $ff95 + ld [H_MULTIPLYBUFFER], a ; $ff9b + ld [H_MULTIPLYBUFFER+1], a ; $ff9c + ld [H_MULTIPLYBUFFER+2], a ; $ff9d + ld [H_MULTIPLYBUFFER+3], a ; $ff9e +.multiplyLoop + ld a, [H_MULTIPLIER] ; $ff99 srl a - ld [H_MULTIPLIER], a ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) - jr nc, .smallMultiplier + ld [H_MULTIPLIER], a ; $ff99 + 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] @@ -22,14 +23,14 @@ _Multiply: ld a, [H_MULTIPLICAND+1] adc c ld [H_MULTIPLYBUFFER+2], a - ld a, [H_MULTIPLYBUFFER+1] + ld a, [H_MULTIPLYBUFFER+1] ; $ff9c ld c, a - ld a, [H_MULTIPLICAND] ; (aliases: H_MULTIPLICAND) + ld a, [H_MULTIPLICAND] ; $ff96 adc c - ld [H_MULTIPLYBUFFER+1], a + ld [H_MULTIPLYBUFFER+1], a ; $ff9c ld a, [H_MULTIPLYBUFFER] ld c, a - ld a, [H_PRODUCT] ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) + ld a, [H_PRODUCT] ; $ff95 adc c ld [H_MULTIPLYBUFFER], a .smallMultiplier @@ -41,103 +42,103 @@ _Multiply: ld a, [H_MULTIPLICAND+1] rl a ld [H_MULTIPLICAND+1], a - ld a, [H_MULTIPLICAND] + ld a, [H_MULTIPLICAND] ; $ff96 rl a - ld [H_MULTIPLICAND], a - ld a, [H_PRODUCT] + ld [H_MULTIPLICAND], a ; $ff96 + ld a, [H_PRODUCT] ; $ff95 rl a - ld [H_PRODUCT], a - jr .loop + ld [H_PRODUCT], a ; $ff95 + jr .multiplyLoop .done ld a, [H_MULTIPLYBUFFER+3] ld [H_PRODUCT+3], a ld a, [H_MULTIPLYBUFFER+2] ld [H_PRODUCT+2], a - ld a, [H_MULTIPLYBUFFER+1] - ld [H_PRODUCT+1], a + ld a, [H_MULTIPLYBUFFER+1] ; $ff9c + ld [H_PRODUCT+1], a ; $ff96 ld a, [H_MULTIPLYBUFFER] - ld [H_PRODUCT], a + ld [H_PRODUCT], a ; $ff95 ret _Divide: xor a - ld [H_DIVIDEBUFFER], a - ld [H_DIVIDEBUFFER+1], a - ld [H_DIVIDEBUFFER+2], a - ld [H_DIVIDEBUFFER+3], a - ld [H_DIVIDEBUFFER+4], a + ld [H_DIVIDEBUFFER], a ; ff9a + ld [H_DIVIDEBUFFER+1], a ; ff9b + ld [H_DIVIDEBUFFER+2], a ; ff9c + ld [H_DIVIDEBUFFER+3], a ; ff9d + ld [H_DIVIDEBUFFER+4], a ; ff9e 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] ; $ff96 sub c ld d, a - ld a, [H_DIVISOR] ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) + ld a, [H_DIVISOR] ; $ff99 ld c, a - ld a, [H_DIVIDEND] ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) + ld a, [H_DIVIDEND] ; $ff95 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 ; $ff95 ld a, d - ld [H_DIVIDEND+1], a ; (aliases: H_MULTIPLICAND) + ld [H_DIVIDEND+1], a ; $ff96 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 ld a, [H_DIVIDEBUFFER+3] rl a ld [H_DIVIDEBUFFER+3], a - ld a, [H_DIVIDEBUFFER+2] + ld a, [H_DIVIDEBUFFER+2] ; $ff9c rl a - ld [H_DIVIDEBUFFER+2], a + ld [H_DIVIDEBUFFER+2], a ; $ff9c ld a, [H_DIVIDEBUFFER+1] 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 ; $ff99 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] ; $ff96 + ld [H_DIVIDEND], a ; $ff95 ld a, [H_DIVIDEND+2] - ld [H_DIVIDEND+1], a ; (aliases: H_MULTIPLICAND) + ld [H_DIVIDEND+1], a ; $ff96 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] ; $ff99 srl a - ld [H_DIVISOR], a ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) + ld [H_DIVISOR], a ; $ff99 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] ; $ff96 + ld [H_REMAINDER], a ; $ff99 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 a, [H_DIVIDEBUFFER+2] ; $ff9c + ld [H_QUOTIENT+1], a ; $ff96 ld a, [H_DIVIDEBUFFER+1] - ld [H_DIVIDEND], a ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) + ld [H_QUOTIENT], a ; $ff95 ret |