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Feb 23, 2003 | 09:04 PM

V8Astro Captain

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From: 600 yds out

Car: Bee-Bowdy

Engine: blowd tree-fity

Transmission: sebin hunnerd

Axle/Gears: fo-tins

Code help...

This is from the 7747 ARJU hack...

Code:

    	*================================================
		* LOOK UP 2D VE2 VALUE
		*	(0 - 6400 RPM)
		*
		* ADD TO VE 3d RESULTS IN $00A9
		*
		* TBL = %VE * 2.56
    	*================================================
D664:            LDAA    L001C  	; RPM/25
D666:            LDX     #$D3C7		; 2D LOOK PU OF VE2
D669:            JSR     LFB49		; 2D LOOK PU 
									;
D66C:            STAA    L00A9		; FUEL FM TBL 
    	*================================================





   	*================================================
	 	* LOOK UP FL 1
	 	* MAIN FUEL PREDICITIONS vs MAP vs RPM, (FL1)
	 	*
	 	* TBL = %VE * 2.56
    	*================================================
D6B2:            LDAA    L0026		; S/D MAP 
D6B4:            LSRA    			; DIV BY 2 FOR LK UP
D6B5:            LDAB    L001C  	; RPM/25
D6B7:            CMPB    #128		; 3200 RPM 
D6B9:            BLS     LD6BD		; BR IF RPM LT 3200
									; ... else
D6BB:            LDAB    #128		; FORCE 3200 RPM
D6BD:  LD6BD     LDX     #$D37C		; POINT TO FL 1 TABLE
D6C0:            JSR     LFB67		; 3D LOOK UP
									;
D6C3:            ADDA    L00A9		; SAVE TOTAL VE RESULT
D6C5:            BCC     LD6C9		; IF NO OVERFLOW
									; ... else
D6C7:            LDAA    #255		; USE 100 % VE
D6C9:  LD6C9     STAA    L00A9		; SAVE VE RESULT
	;-------------------------------------------------

If I'm reading this right then the code stored the VE2 value in $00A9 (D66C). Then at D6C3 the VE1 value is added to $00A9. Then at D6C5 there is a break if $00A9 is greater than #255, if so it is limited to #255 by D6C7.

So the total for VE1 and VE2 added together is 255.

I know this was covered in an earlier post of mine, I just want to understand it. Before I thought that I could have 255 in both tables. Now I think I see why it doesn't work like that.

Last edited by V8Astro Captain; Feb 23, 2003 at 09:07 PM.

Feb 24, 2003 | 06:36 AM

RBob

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From: Chasing Electrons

Car: check

Engine: check

Transmission: check

Re: Code help...

Quote:

Originally posted by V8Astro Captain
This is from the 7747 ARJU hack...

Code:

*================================================ * LOOK UP 2D VE2 VALUE * (0 - 6400 RPM) * * ADD TO VE 3d RESULTS IN $00A9 * * TBL = %VE * 2.56 *================================================ D664: LDAA L001C ; RPM/25 D666: LDX #$D3C7 ; 2D LOOK PU OF VE2 D669: JSR LFB49 ; 2D LOOK PU ; D66C: STAA L00A9 ; FUEL FM TBL *================================================ *================================================ * LOOK UP FL 1 * MAIN FUEL PREDICITIONS vs MAP vs RPM, (FL1) * * TBL = %VE * 2.56 *================================================ D6B2: LDAA L0026 ; S/D MAP D6B4: LSRA ; DIV BY 2 FOR LK UP D6B5: LDAB L001C ; RPM/25 D6B7: CMPB #128 ; 3200 RPM D6B9: BLS LD6BD ; BR IF RPM LT 3200 ; ... else D6BB: LDAB #128 ; FORCE 3200 RPM D6BD: LD6BD LDX #$D37C ; POINT TO FL 1 TABLE D6C0: JSR LFB67 ; 3D LOOK UP ; D6C3: ADDA L00A9 ; SAVE TOTAL VE RESULT D6C5: BCC LD6C9 ; IF NO OVERFLOW ; ... else D6C7: LDAA #255 ; USE 100 % VE D6C9: LD6C9 STAA L00A9 ; SAVE VE RESULT ;-------------------------------------------------

If I'm reading this right then the code stored the VE2 value in $00A9 (D66C). Then at D6C3 the VE1 value is added to $00A9. Then at D6C5 there is a break if $00A9 is greater than #255, if so it is limited to #255 by D6C7.

So the total for VE1 and VE2 added together is 255.

I know this was covered in an earlier post of mine, I just want to understand it. Before I thought that I could have 255 in both tables. Now I think I see why it doesn't work like that.

You found it. BCC is Branch if Carry Clear. So after the two VE's are added together and if there is no overflow (no carry), the branch occurs and the sum of the VE values are used as is. If the carry flag was set, the branch does not occur and the VE value is set to 255, the largest 8 bit value.

Then: 255 * 0.39 = 99.5%, the largest total VE value.

RBob.