Question about Propeller Asm.

MacGeek117

I'm trying to port a stepper motor driver that uses the L297 from Spin to assembly, but I'm having troubles. In the Spin code there is a conditional loop based on a 'flag' variable:

ifnot go
  repeat until go

How would I do this in assembly?(I'm very new!)
RoboGeek

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Paul Baker

The answer depends on where/what go is and what is affecting go so that the loop is finally exited.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Graham Stabler

have a look at the various compare commands in the manual and the effect of setting the wz or wc, then you can use if_c or if_nc etc to jump past a jump command that is causing the loop when your go variable equals something or is greater than zero or whatever.

basically rtfm [noparse]:)[/noparse]

Graham

CJ

you can wait for a non-zero by this (note all mentioned registers have to be changed to appropriate labels)

:loop rdbyte cogregister, flagaddress
tjz cogregister, #:loop

not 100% on the syntax, but this would be the simplest way to wait for a non-zero flag, falls through on anything but zero

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MacGeek117

Thank you for pointing me in that direction, CJ. I will be using tjnz. I never saw those commands. Thank you for all your help!
RoboGeek

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"I reject your reality and subsitute my own!"

Adam Savage, Mythbusters
www.parallax.com
www.goldmine-elec.com
www.expresspcb.com
www.startrek.com
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