Difference between revisions of "Programming:Integer Division"
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(the new fast division added) |
(→Fast 32bit division: correction and additional information is added) |
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| Line 179: | Line 179: | ||
'''Not used:''' IX, IY | '''Not used:''' IX, IY | ||
| + | |||
| + | '''CPC Cycles:''' 1080-2572 (1826 on average), 270-643 usec (456 on average) | ||
<pre> | <pre> | ||
| − | + | div_r macro | |
| − | local | + | local t2 |
| − | + | ||
EX DE, HL | EX DE, HL | ||
ADD HL, HL | ADD HL, HL | ||
EX DE, HL | EX DE, HL | ||
| − | + | ADC HL, HL | |
| − | |||
| − | |||
LD A, L | LD A, L | ||
ADD A, C | ADD A, C | ||
LD A, H | LD A, H | ||
ADC A, B | ADC A, B | ||
| − | + | JR NC, t2 | |
ADD HL, BC | ADD HL, BC | ||
INC DE | INC DE | ||
| − | + | t2 | |
endm | endm | ||
| + | div_e macro | ||
| + | local t1,t2 | ||
| + | EX DE, HL | ||
| + | ADD HL, HL | ||
| + | EX DE, HL | ||
| + | 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 | div32x16 proc ; BCDE = HLDE/BC, HL = HLDE%BC | ||
| − | local | + | local DIV16, DIV32R, DIV32F |
DEC BC | DEC BC | ||
LD A, B | LD A, B | ||
| Line 214: | Line 230: | ||
LD A, B | LD A, B | ||
ADC A, H | ADC A, H | ||
| − | + | JR NC, DIV16 | |
PUSH DE | PUSH DE | ||
EX DE, HL | EX DE, HL | ||
LD HL, 0000 | LD HL, 0000 | ||
| − | CALL | + | CALL DIV32R |
EX DE, HL | EX DE, HL | ||
EX (SP), HL | EX (SP), HL | ||
EX DE, HL | EX DE, HL | ||
| − | CALL | + | CALL DIV32F |
POP BC | POP BC | ||
RET | RET | ||
| − | + | DIV16 | |
| − | CALL | + | CALL DIV32F |
LD BC, 0000 | LD BC, 0000 | ||
RET | RET | ||
| − | + | DIV32R ; DE = HLDE/(-BC), HL = HLDE%(-BC), -BC < $8000 | |
| − | CALL | + | CALL $+3 |
| − | + | ||
rept 8 | rept 8 | ||
| − | + | div_r | |
| + | endm | ||
| + | RET | ||
| + | endp | ||
| + | DIV32E ; DE = HLDE/(-BC), HL = HLDE%(-BC) | ||
| + | CALL $+3 | ||
| + | rept 8 | ||
| + | div_e | ||
endm | endm | ||
RET | RET | ||
endp | endp | ||
</pre> | </pre> | ||
| + | |||
== Web links == | == Web links == | ||
Revision as of 11:31, 16 November 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
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: 1080-2572 (1826 on average), 270-643 usec (456 on average)
div_r macro
local t2
EX DE, HL
ADD HL, HL
EX DE, HL
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
EX DE, HL
ADD HL, HL
EX DE, HL
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, DIV32F
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 DIV32F
POP BC
RET
DIV16
CALL DIV32F
LD BC, 0000
RET
DIV32R ; DE = HLDE/(-BC), HL = HLDE%(-BC), -BC < $8000
CALL $+3
rept 8
div_r
endm
RET
endp
DIV32E ; DE = HLDE/(-BC), HL = HLDE%(-BC)
CALL $+3
rept 8
div_e
endm
RET
endp
