[Coco] assembly language question.

[Arthur Flexser]

The example seems a bit unusual in that you're comparing a 16-bit quantity
(the X register) with an 8-bit one (due to the use of the 'less than'
sign).  I'm guessing that that would cause only the LSB of X ($FA) to be
compared to <$000A (=$0A) with the outcome that the BLO no branch since $FA
is greater than $0A by an unsigned comparison.

Art
On Wed, Feb 3, 2010 at 9:10 PM, Gene Heskett <gene.heskett at verizon.net>wrote:


> Greets all;

>

> I've read through the moto programmers manual for the 6809 for the cmp

> functions, and am still confused.  The cmp function is a subtract function

> where the answer is thrown away, only affecting the CC flags so that a

> following beq or blo will take the correct jump.  But somehow, it isn't

> clear

> which is subtracted from what.

>

> Given that regs.x contains $02FA, and that the integer memory location

> referenced by LblName contains $000A, will the blo take, or be ignored

> here?

>

>        cmpx  <LblName memory address in DP that holds the $000A above

>        blo     somewhere else

>

> Thanks.

>

> --

> Cheers, Gene

> "There are four boxes to be used in defense of liberty:

>  soap, ballot, jury, and ammo. Please use in that order."

> -Ed Howdershelt (Author)

>

> <cesarb> Damn, every time I spawn, qf-client-x11 locks hard

> <Zoid> Don't die?

> <Knghtbrd> good incentive.

>

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