Code:
'****************************************************************
'* Name : Test_SkiDIV.pbp *
'* Author : Darrel Taylor *
'* Date : 9/9/2008 *
'* Version : 1.0 *
'* Thread : instruction execution time *
'* http://www.picbasic.co.uk/forum/showthread.php?p=61992 *
'****************************************************************
;****************************************************************
;* DIV : 32 x 32 divide *
;* Input : R0 / R1 *
;* Output : R0 = quotient *
;* : R2 = remainder *
;* Notes : R2 = R0 MOD R1 *
;****************************************************************
;1755 bytes used
DEFINE OSC 40
DEFINE HSER_TXSTA 24h 'Hser transmit status init
DEFINE HSER_RCSTA 90h 'Hser receive status init
DEFINE HSER_BAUD 38400 'Hser baud rate
DEFINE HSER_CLROERR 1 'Hser clear overflow automatically
DEFINE SKI_DIV_OPT 1
AL VAR LONG
BL VAR LONG
SkiQ VAR LONG ; ASM quotient
SkiR VAR LONG ; ASM remainder
PBPQ VAR LONG ; PBP quotient
PBPR VAR LONG ; PBP remainder
AW VAR WORD
BW VAR WORD
RW VAR WORD
ERROR VAR BIT
For AL = 0 to 1000
ERROR = 0
For BL = 0 to 1000
@ MOVE?NN _AL, R0
@ MOVE?NN _BL, R1 ; AL / BL
@ L?CALL #DIVS
@ MOVE?ANN R0, _SkiQ
@ MOVE?NN R2, _SkiR
PBPQ = AL / BL ; do same in PBP
PBPR = AL // BL
if SkiQ != PBPQ then
HSEROUT [" Quotient Error: A=",DEC AL," B=",DEC BL, _
" Ski=",dec SkiQ," PBP=",DEC PBPQ,13,10]
ERROR = 1
endif
if SkiR != PBPR then
HSEROUT ["Remainder Error: A=",DEC AL," B=",DEC BL, _
" Ski=",dec SkiR," PBP=",DEC PBPR,13,10]
ERROR = 1
endif
next BL
if ERROR = 0 then HSEROUT ["A=",dec AL," No ERRORs",13,10]
next AL
stop
; ---- nothing has been changed below
ASM
ifdef DIVS_USED
LIST
#DIVS
clrf R3 + 3 ; Clear sign difference indicator
btfss R0 + 3, 7 ; Check for R0 negative
bra #divchkr1 ; Not negative
btg R3 + 3, 7 ; Flip sign indicator
clrf WREG ; Clear W for subtracts
negf R0 ; Flip value to plus
subfwb R0 + 1, F
subfwb R0 + 2, F
subfwb R0 + 3, F
#divchkr1
btfss R1 + 3, 7 ; Check for R1 negative
bra #divdo ; Not negative
btg R3 + 3, 7 ; Flip sign indicator
clrf WREG ; Clear W for subtracts
negf R1 ; Flip value to plus
subfwb R1 + 1, F
subfwb R1 + 2, F
subfwb R1 + 3, F
bra #divdo ; Skip unsigned entry
NOLIST
DIV_USED = 1
endif
ifdef DIV_USED
LIST
#DIV
ifdef DIVS_USED
clrf R3 + 3 ; Clear sign difference indicator
endif
#divdo
clrf R2 ; Do the divide
clrf R2 + 1
clrf R2 + 2
clrf R2 + 3
movlw 32
movwf R3
;added to speed up s-31 divide op's by ignoring zero'd bytes
ifdef SKI_DIV_OPT
if ( SKI_DIV_OPT == 1 )
SkiOpt
movf R0 + 3, W ; IF R0.byte3 (low 7 bits) = 0
bcf W, 7 ; Clear 'sign'
bnz #divloop ;
movf R1 + 3, W ; AND R1.byte3 (low 7 bits)=0 then
bcf W, 7 ; Clear 'sign'
bnz #divloop
;but only check Rx+3.7 the first time thru (1st time)
;after that, instead of a byte shift,
;shift everything << 7 (2nd time),
;then do 2 more byte shifts if possible
Ski_Shift7
movlw 6
movwf R3
rlcf R0, F ;shift 7 times
rlcf R0 + 1, F
rlcf R0 + 2, F
rlcf R0 + 3, F
rlcf R1, F
rlcf R1 + 1, F
rlcf R1 + 2, F
rlcf R1 + 3, F
movlw 1
subwf R3, F
movf R3, W
btfss STATUS, Z
bra Ski_Shift7
;check again after 7 shifts
movlw 25
movwf R3
Ski_Shift3
movf R0 + 3, W ; IF R0.byte3 = 0
bnz #divloop ;
movf R1 + 3, W ; AND R1.byte3 = 0 then
bnz #divloop
movff R0 + 2, R0 + 3 ; and preshift R0
movff R0 + 1, R0 + 2
movff R0 + 0, R0 + 1
clrf R0
movff R1 + 2, R1 + 3 ; and R1 over 8 bits
movff R1 + 1, R1 + 2
movff R1 + 0, R1 + 1
clrf R1
movlw 8
subwf R3, F
movf R3, W
btfss STATUS, C ;if it's 1 (actually 1-8)
bra Ski_Shift3 ;jump out
bra SkiOpt
endif
endif
;above added to speed divide operations
;added to speed up s-31 divides by skipping clr'd bits in divisor/dividend
ifdef SKI_DIV_OPT
if ( SKI_DIV_OPT == 2 )
SkiOpt2
;change 7 to 6
btfsc R0 + 3, 6 ; if highest bit set, goto divloop
bra #divloop
;change 7 to 6
btfsc R1 + 3, 6 ; if highest bit set, goto divloop
bra #divloop
;check Rx+3.6 instead of .7 and do shift if possible
;streamlined code here...old stuff is gone...
bcf STATUS, C ;clr carry-shift over complete R0
rlcf R0, F ;shift R0, .7 into carry
rlcf R0 + 1, F ;shift R0+1
rlcf R0 + 2, F ;shift R0+2
rlcf R0 + 3, F ;shift R0+3
bcf STATUS, C ;clr carry-shift over complete R1
rlcf R1, F ;shift R1, .7 into carry
rlcf R1 + 1, F ;shift R1+1
rlcf R1 + 2, F ;shift R1+2
rlcf R1 + 3, F ;shift R1+3
movlw 1 ;subtract one from the loop count
subwf R3, F
movf R3, W
btfss STATUS, Z ;stop if no more loops
bra SkiOpt2
endif
endif
;above added to speed up divides at the bit level
#divloop
rlcf R0 + 3, W
rlcf R2, F
rlcf R2 + 1, F
rlcf R2 + 2, F
rlcf R2 + 3, F
movf R1, W
subwf R2, F
movf R1 + 1, W
subwfb R2 + 1, F
movf R1 + 2, W
subwfb R2 + 2, F
movf R1 + 3, W
subwfb R2 + 3, F
bc #divok
movf R1, W
addwf R2, F
movf R1 + 1, W
addwfc R2 + 1, F
movf R1 + 2, W
addwfc R2 + 2, F
movf R1 + 3, W
addwfc R2 + 3, F
bcf STATUS, C
#divok
rlcf R0, F
rlcf R0 + 1, F
rlcf R0 + 2, F
rlcf R0 + 3, F
decfsz R3, F
bra #divloop
ifdef DIVS_USED
btfss R3 + 3, 7 ; Should result be negative?
bra #divdone ; Not negative
clrf WREG ; Clear W for subtracts
negf R0 ; Flip quotient to minus
subfwb R0 + 1, F
subfwb R0 + 2, F
subfwb R0 + 3, F
negf R2 ; Flip remainder to minus
subfwb R2 + 1, F
subfwb R2 + 2, F
subfwb R2 + 3, F
#divdone
endif
movf R0, W ; Get low byte to W
goto DUNN
NOLIST
DUNN_USED = 1
endif
ENDASM
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