What does this section of code do?!?!
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What does this section of code do?!?!
Like the title says. It looks like what's stored to A and B is either overwritten or not used at all. Enlightenment, please?
Code:
;-------------------------------------------------
;
;
;
;-------------------------------------------------
D8D8: BRCLR L0036,#$08,LD8F2 ; BR IF NOT b3, ALDL MODE 4
D8DC: LDAA L0160
D8DF: BITA #$04 ; b2
D8E1: BEQ LD8F2
; ... Else
D8E3: LDAB L0162
D8E6: CLRA
D8E7: PSHB
D8E8: PSHA
D8E9: PULX
D8EA: LDD #$FFFF
D8ED: IDIV
D8EE: STX L00D5
D8F0: BRA LD95A Last edited by bl85c; Oct 14, 2010 at 06:04 PM.
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Re: What does this section of code do?!?!
It is a routine to modify the target AFR directly via ALDL Mode 4 and bypass the normal PE AFR calculation.
The value that is loaded into A (L0160) is a status bit that is checked before proceeding.
The value that is loaded into B (L0162) is the new AFR from the Mode 4 command message.
The value that is loaded into A (L0160) is a status bit that is checked before proceeding.
The value that is loaded into B (L0162) is the new AFR from the Mode 4 command message.
Last edited by tequilaboy; Oct 15, 2010 at 07:47 PM.
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Re: What does this section of code do?!?!
Like the title says. It looks like what's stored to A and B is either overwritten or not used at all. Enlightenment, please?
Code:
;-------------------------------------------------
;
;
;
;-------------------------------------------------
D8D8: BRCLR L0036,#$08,LD8F2 ; BR IF NOT b3, ALDL MODE 4
D8DC: LDAA L0160
D8DF: BITA #$04 ; b2
D8E1: BEQ LD8F2
; ... Else
D8E3: LDAB L0162
D8E6: CLRA
D8E7: PSHB
D8E8: PSHA
D8E9: PULX
D8EA: LDD #$FFFF
D8ED: IDIV
D8EE: STX L00D5
D8F0: BRA LD95A So.....
L00D5 = ffffh/L0162
Hope that makes sense.
Last edited by alvanwie; Oct 15, 2010 at 07:29 PM.
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Re: What does this section of code do?!?!
Ah, I'm reading it wrong then. Looks to me like what was loaded onto A was subsequently cleared then commanded to push to the stack. So why is there a clear A command before A is put on the stack?
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From: Dyer, In
Car: 91 Camaro RS
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Re: What does this section of code do?!?!
Sorry, looks like i got that slightly wrong.
B is loaded with the value from L0162 and A is cleared to zero. These 8 bit values are pushed onto the stack B first then A. They are then popped off of the stack into the 16 bit X register (high byte first) so effectively X (16 bit) contains the value from L0162.
So,,,
L00D5 (16 bit) = ffffh/L0162
B is loaded with the value from L0162 and A is cleared to zero. These 8 bit values are pushed onto the stack B first then A. They are then popped off of the stack into the 16 bit X register (high byte first) so effectively X (16 bit) contains the value from L0162.
So,,,
L00D5 (16 bit) = ffffh/L0162
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Re: What does this section of code do?!?!
Thanks, that helps me with what I'm writing. Finding enough space for this hack is getting tedious.
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