diff options
Diffstat (limited to 'engine/multiply_divide.asm')
| -rwxr-xr-x | engine/multiply_divide.asm | 100 |
1 files changed, 50 insertions, 50 deletions
diff --git a/engine/multiply_divide.asm b/engine/multiply_divide.asm index 7726a2db..e6e6e89c 100755 --- a/engine/multiply_divide.asm +++ b/engine/multiply_divide.asm @@ -2,17 +2,16 @@ _Multiply: ; 37d41 (d:7d41) ld a, $8 ld b, a xor a - 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 + 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] srl a - 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 [H_MULTIPLIER], a ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) + jr nc, .smallMultiplier ld a, [H_MULTIPLYBUFFER+3] ld c, a ld a, [H_MULTIPLICAND+2] @@ -23,82 +22,83 @@ _Multiply: ; 37d41 (d:7d41) ld a, [H_MULTIPLICAND+1] adc c ld [H_MULTIPLYBUFFER+2], a - ld a, [H_MULTIPLYBUFFER+1] ; $ff9c + ld a, [H_MULTIPLYBUFFER+1] ld c, a - ld a, [H_MULTIPLICAND] ; $ff96 + ld a, [H_MULTIPLICAND] ; (aliases: H_MULTIPLICAND) adc c - ld [H_MULTIPLYDBUFFER+1], a ; $ff9c + ld [H_MULTIPLYBUFFER+1], a ld a, [H_MULTIPLYBUFFER] ld c, a - ld a, [H_PRODUCT] ; $ff95 + ld a, [H_PRODUCT] ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) adc c ld [H_MULTIPLYBUFFER], a .smallMultiplier dec b jr z, .done - ld a, [H_MULTIPLICAND] + ld a, [H_MULTIPLICAND+2] sla a ld [H_MULTIPLICAND+2], a ld a, [H_MULTIPLICAND+1] rl a ld [H_MULTIPLICAND+1], a - ld a, [H_MULTIPLICAND] ; $ff96 + ld a, [H_MULTIPLICAND] rl a - ld [H_MULTIPLICAND], a ; $ff96 - ld a, [H_PRODUCT] ; $ff95 + ld [H_MULTIPLICAND], a + ld a, [H_PRODUCT] rl a - ld [H_PRODUCT], a ; $ff95 - jr .multiplyLoop + ld [H_PRODUCT], a + jr .loop .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] ; $ff9c - ld [H_PRODUCT+1], a ; $ff96 - ld [H_PRODUCT], a ; $ff95 + ld a, [H_MULTIPLYBUFFER+1] + ld [H_PRODUCT+1], a + ld a, [H_MULTIPLYBUFFER] + ld [H_PRODUCT], a ret _Divide: ; 37da5 (d:7da5) xor 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 [H_DIVIDEBUFFER], a + ld [H_DIVIDEBUFFER+1], a + ld [H_DIVIDEBUFFER+2], a + ld [H_DIVIDEBUFFER+3], a + ld [H_DIVIDEBUFFER+4], a ld a, $9 ld e, a .asm_37db3 ld a, [H_DIVIDEBUFFER] ld c, a - ld a, [H_DIVIDEND+1] ; $ff96 + ld a, [H_DIVIDEND+1] ; (aliases: H_MULTIPLICAND) sub c ld d, a - ld a, [H_DIVISOR] ; $ff99 + ld a, [H_DIVISOR] ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) ld c, a - ld a, [H_DIVIDEND] ; $ff95 + ld a, [H_DIVIDEND] ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) sbc c jr c, .asm_37dce - ld [H_DIVIDEND], a ; $ff95 + ld [H_DIVIDEND], a ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) ld a, d - ld [H_DIVIDEND+1], a ; $ff96 + ld [H_DIVIDEND+1], a ; (aliases: H_MULTIPLICAND) ld a, [H_DIVIDEBUFFER+4] inc a ld [H_DIVIDEBUFFER+4], a jr .asm_37db3 .asm_37dce - ld a, b + ld a, b cp $1 - jr z, .done + jr z, .asm_37e18 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] ; $ff9c + ld a, [H_DIVIDEBUFFER+2] rl a - ld [H_DIVIDEBUFFER+2], a ; $ff9c + ld [H_DIVIDEBUFFER+2], a ld a, [H_DIVIDEBUFFER+1] rl a ld [H_DIVIDEBUFFER+1], a @@ -107,13 +107,13 @@ _Divide: ; 37da5 (d:7da5) ld a, $8 ld e, a ld a, [H_DIVIDEBUFFER] - ld [H_DIVISOR], a ; $ff99 + ld [H_DIVISOR], a ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) xor a ld [H_DIVIDEBUFFER], a - ld a, [H_DIVIDEND+1] ; $ff96 - ld [H_DIVIDEND], a ; $ff95 + ld a, [H_DIVIDEND+1] ; (aliases: H_MULTIPLICAND) + ld [H_DIVIDEND], a ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) ld a, [H_DIVIDEND+2] - ld [H_DIVIDEND+1], a ; $ff96 + ld [H_DIVIDEND+1], a ; (aliases: H_MULTIPLICAND) ld a, [H_DIVIDEND+3] ld [H_DIVIDEND+2], a .asm_37e04 @@ -122,22 +122,22 @@ _Divide: ; 37da5 (d:7da5) jr nz, .asm_37e0a dec b .asm_37e0a - ld a, [H_DIVIDEND+4] ; $ff99 + ld a, [H_DIVISOR] ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) srl a - ld [H_REMAINDER], a ; $ff99 + ld [H_DIVISOR], a ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) ld a, [H_DIVIDEBUFFER] rr a ld [H_DIVIDEBUFFER], a jr .asm_37db3 -.done - ld a, [H_DIVIDEND+1] ; $ff96 - ld [H_REMAINDER], a ; $ff99 +.asm_37e18 + ld a, [H_DIVIDEND+1] ; (aliases: H_MULTIPLICAND) + ld [H_REMAINDER], a ; (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN) 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] ; $ff9c - ld [H_QUOTIENT+1], a ; $ff96 + ld a, [H_DIVIDEBUFFER+2] + ld [H_QUOTIENT+1], a ; (aliases: H_MULTIPLICAND) ld a, [H_DIVIDEBUFFER+1] - ld [H_QUOTIENT], a ; $ff95 - ret + ld [H_DIVIDEND], a ; (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT) + ret
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