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EDIT: It'll fail above 24 bits...and if it's negative...Nothing in there shifting over the bytes!
EDIT #2 : Replaced code in post #15
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EDIT: It'll fail above 24 bits...and if it's negative...Nothing in there shifting over the bytes!
EDIT #2 : Replaced code in post #15
Last edited by skimask; - 11th September 2008 at 05:43. Reason: Edit's abound...
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Ok, this looks good...er...I think...
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 'throw in a little bit of clock counting? @ MOVE?ANN R0, _SkiQ @ MOVE?NN R2, _SkiR PBPQ = AL / BL ; do same in PBP PBPR = AL // BL 'throw in a bit of clock counting here too? 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 bcf STATUS, C 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 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
Last edited by skimask; - 11th September 2008 at 06:34.
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Now I get nothing with SKI_DIV_OPT 1.
SKI_DIV_OPT 2 still looks the same.
Are you still using the Simulator?
<br>
DT
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Yes, yes, yes... I know...Don't use the simulator.Originally Posted by Darrel Taylor
I'll get on it good this weekend with hardware (probably just temporarily reprogram my OBD reader for grins)...
Ok, So, Opt 1 - nothing - What mean you by 'nothing'? Zero's all the way around?
Opt 2 - gets roughly the same garbage as before?
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No serial output at all. It's stuck in the optimize section, getting dizzy doing loops.
May have something to do with subtracting 8 loops from what's now 25 (was 32), but I'm not sure.
Same stuff. Quotient is 0, Remainder has the full A value.Opt 2 - gets roughly the same garbage as before?
<br>
DT
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Jeeze...up in SkiShift3...
Not going to get much of a carry from that am I?Code:movlw 8 subwf R3, F movf R3, W btfss STATUS, C ;if it's 1 (actually 1-8) bra Ski_Shift3 ;jump out
The subwf should set STATUS as appropriate, should be able to remove movf R3, W above the branch.
I'm still looking thru my code in MCS...
Might not have to worry about the most-sig-bit in R0/R1 since it's preset to 0 by the code at the beginning, therefore, that'll negate checking bit 30 instead of bit 31 of R0/R1.
Last edited by skimask; - 11th September 2008 at 23:18.
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Did some pencil/paper work on the s31 divide operations at the bit level...
Trying to optimize at the bit level is fruitless. Preshifting bits accomplishes the same thing that #divloop does except the fact that if the subtraction fails, #divloop restores the working registers (Rx). A few cycles may be wasted there with the restoration of the R(x) register, but those same cycles that may have been saved there, would have been used in the preshifting anyway.
Optimizing at the byte level should still show a fair amount of cycle savings...
More pencil/paper work...
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