Difference between revisions of "Programming:Integer Division"
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+ | == 8bit division == | ||
+ | |||
+ | '''Input:''' HL=Value1, C=Value2 | ||
+ | |||
+ | '''Output:''' L=Value1/Value2, H=Value1 MOD Value2 | ||
+ | |||
+ | '''Destroyed:''' AF,BC | ||
+ | |||
+ | <pre> | ||
+ | LD B,8 | ||
+ | Div_Next: | ||
+ | ADD HL,HL | ||
+ | LD A,H | ||
+ | SUB C | ||
+ | JR C,Div_NXTB | ||
+ | LD H,A | ||
+ | INC L | ||
+ | Div_NXTB: | ||
+ | DJNZ Div_Next | ||
+ | RET | ||
+ | </pre> | ||
+ | |||
== 16bit division == | == 16bit division == | ||
Line 92: | Line 114: | ||
'''Destroyed:''' AF,DE,IY | '''Destroyed:''' AF,DE,IY | ||
+ | |||
+ | '''CPC Cycles:''' approximately 7800, 1900 usec | ||
+ | |||
+ | '''Size:''' 91 bytes | ||
<pre> | <pre> | ||
Line 146: | Line 172: | ||
ret ;IY,BC=Value1 DIV Value2 | ret ;IY,BC=Value1 DIV Value2 | ||
</pre> | </pre> | ||
+ | |||
+ | == Fast 32bit division == | ||
+ | |||
+ | '''Input:''' HL,DE=Value1, BC=Value2 | ||
+ | |||
+ | '''Output:''' BCDE=Value1/Value2, HL=Value1 MOD Value2 | ||
+ | |||
+ | '''Destroyed:''' AF | ||
+ | |||
+ | '''Not used:''' IX, IY | ||
+ | |||
+ | '''CPC Cycles:''' 1016-2444 (1730 on average), 254-611 usec (432 on average) | ||
+ | |||
+ | '''Size:''' 277 bytes | ||
+ | |||
+ | <pre> | ||
+ | div_r macro | ||
+ | local t2 | ||
+ | SLA E | ||
+ | RL D | ||
+ | ADC HL, HL | ||
+ | |||
+ | LD A, L | ||
+ | ADD A, C | ||
+ | LD A, H | ||
+ | ADC A, B | ||
+ | JR NC, t2 | ||
+ | |||
+ | ADD HL, BC | ||
+ | INC DE | ||
+ | t2 | ||
+ | endm | ||
+ | div_e macro | ||
+ | local t1,t2 | ||
+ | SLA E | ||
+ | RL D | ||
+ | ADC HL, HL | ||
+ | JR C, t1 | ||
+ | |||
+ | LD A, L | ||
+ | ADD A, C | ||
+ | LD A, H | ||
+ | ADC A, B | ||
+ | JR NC, t2 | ||
+ | t1 | ||
+ | ADD HL, BC | ||
+ | INC DE | ||
+ | t2 | ||
+ | endm | ||
+ | div32x16 proc ; BCDE = HLDE/BC, HL = HLDE%BC | ||
+ | local DIV16, DIV32R, DIV32E | ||
+ | DEC BC | ||
+ | LD A, B | ||
+ | CPL | ||
+ | LD B, A | ||
+ | LD A, C | ||
+ | CPL | ||
+ | LD C, A | ||
+ | ADD A, L | ||
+ | LD A, B | ||
+ | ADC A, H | ||
+ | JR NC, DIV16 | ||
+ | |||
+ | PUSH DE | ||
+ | EX DE, HL | ||
+ | LD HL, 0000 | ||
+ | CALL DIV32R | ||
+ | EX DE, HL | ||
+ | EX (SP), HL | ||
+ | EX DE, HL | ||
+ | CALL DIV32E | ||
+ | POP BC | ||
+ | RET | ||
+ | DIV16 | ||
+ | CALL DIV32E | ||
+ | LD BC, 0000 | ||
+ | RET | ||
+ | DIV32R ; DE = HLDE/(-BC), HL = HLDE%(-BC), -BC < $8000 | ||
+ | CALL $+3 | ||
+ | rept 8 | ||
+ | div_r | ||
+ | endm | ||
+ | RET | ||
+ | DIV32E ; DE = HLDE/(-BC), HL = HLDE%(-BC) | ||
+ | CALL $+3 | ||
+ | rept 8 | ||
+ | div_e | ||
+ | endm | ||
+ | RET | ||
+ | endp | ||
+ | </pre> | ||
+ | |||
+ | == Web links == | ||
+ | |||
+ | * [http://www.smspower.org/Development/DivMod Division implementation for the Sega Master System] | ||
+ | * [http://map.tni.nl/articles/mult_div_shifts.php Multiplications and divisions on the MSX Assembly Page] | ||
+ | |||
[[Category:Programming]] | [[Category:Programming]] |
Latest revision as of 08:27, 26 December 2015
Contents
8bit division
Input: HL=Value1, C=Value2
Output: L=Value1/Value2, H=Value1 MOD Value2
Destroyed: AF,BC
LD B,8 Div_Next: ADD HL,HL LD A,H SUB C JR C,Div_NXTB LD H,A INC L Div_NXTB: DJNZ Div_Next RET
16bit division
Input: BC=Value1, DE=Value2
Output: HL=Value1/Value2, DE=Value1 MOD Value2
Destroyed: AF,BC
clcd16 ld a,e or d ld hl,0 ret z ld a,b ld b,16 clcd161 rl c rla adc hl,hl sbc hl,de jr nc,clcd162 add hl,de clcd162 ccf djnz clcd161 ex de,hl rl c rla ld h,a ld l,c ret
24bit division
Input: A,BC=Value1, DE=Value2
Output: HL=Value1/Value2, DE=Value1 MOD Value2
Destroyed: AF,BC,IX,IYL
clcdiv db #dd:ld l,e db #dd:ld h,d ;IX=Value2 ld e,a ;E,BC=Value1(Counter) ld hl,0 db #dd:ld a,l db #dd:or h ret z ld d,l ;D,HL=CalcVar db #fd:ld l,24 ;IYL=Counter clcdiv1 rl c rl b rl e rl l rl h rl d ld a,l db #dd:sub l ld l,a ld a,h db #dd:sbc h ld h,a ld a,d sbc 0 ld d,a ;D,HL=D,HL-IX jr nc,clcdiv2 ld a,l db #dd:add l ld l,a ld a,h db #dd:adc h ld h,a ld a,d adc 0 ld d,a scf clcdiv2 ccf db #fd:dec l jr nz,clcdiv1 ex de,hl ;DE=Value1 MOD Value2 rl c rl b ld l,c ld h,b ;HL=Value1 DIV Value2 ret
32bit division
Input: IY,BC=Value1, IX=Value2
Output: IY,BC=Value1/Value2, HL=Value1 MOD Value2
Destroyed: AF,DE,IY
CPC Cycles: approximately 7800, 1900 usec
Size: 91 bytes
clcd32c db 0 clcd32 ld hl,0 db #dd:ld a,l db #dd:or h ret z ;IY,BC=Value1(Counter) ld de,0 ;DE,HL=CalcVar ld a,32 ;Set Counter to 32 clcd321 ld (clcd32c),a rl c rl b db #fd:ld a,l:rla:db #fd:ld l,a db #fd:ld a,h:rla:db #fd:ld h,a rl l rl h rl e rl d ld a,l db #dd:sub l ld l,a ld a,h db #dd:sbc h ld h,a ld a,e sbc 0 ld e,a ld a,d sbc 0 ld d,a jr nc,clcd322 ld a,l db #dd:add l ld l,a ld a,h db #dd:adc h ld h,a ld a,e adc 0 ld e,a ld a,d adc 0 ld d,a scf clcd322 ccf ld a,(clcd32c) dec a jr nz,clcd321 ;HL=Value1 MOD Value2 rl c rl b db #fd:ld a,l:rla:db #fd:ld l,a db #fd:ld a,h:rla:db #fd:ld h,a ret ;IY,BC=Value1 DIV Value2
Fast 32bit division
Input: HL,DE=Value1, BC=Value2
Output: BCDE=Value1/Value2, HL=Value1 MOD Value2
Destroyed: AF
Not used: IX, IY
CPC Cycles: 1016-2444 (1730 on average), 254-611 usec (432 on average)
Size: 277 bytes
div_r macro local t2 SLA E RL D ADC HL, HL LD A, L ADD A, C LD A, H ADC A, B JR NC, t2 ADD HL, BC INC DE t2 endm div_e macro local t1,t2 SLA E RL D ADC HL, HL JR C, t1 LD A, L ADD A, C LD A, H ADC A, B JR NC, t2 t1 ADD HL, BC INC DE t2 endm div32x16 proc ; BCDE = HLDE/BC, HL = HLDE%BC local DIV16, DIV32R, DIV32E DEC BC LD A, B CPL LD B, A LD A, C CPL LD C, A ADD A, L LD A, B ADC A, H JR NC, DIV16 PUSH DE EX DE, HL LD HL, 0000 CALL DIV32R EX DE, HL EX (SP), HL EX DE, HL CALL DIV32E POP BC RET DIV16 CALL DIV32E LD BC, 0000 RET DIV32R ; DE = HLDE/(-BC), HL = HLDE%(-BC), -BC < $8000 CALL $+3 rept 8 div_r endm RET DIV32E ; DE = HLDE/(-BC), HL = HLDE%(-BC) CALL $+3 rept 8 div_e endm RET endp