What "Rr" in assembly means

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I cannot find what "Rr" register name in assembly mnemonics means. "Rd" is probably Destination register but where comes the "r" from? "Source"?

Last Edited: Fri. Nov 22, 2019 - 11:37 AM
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Where are you looking?

 

Show an example!

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Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
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Where are you looking?

 

Show an example!

presumably something like this in the opcode manual:

 

 

As "operands" says, in this case "r" is a placeholder for some register number between 0 and 31 so you can "STS 0x123, R17", "STS 0x456,R29" or more generally "STS k, Rr" (0 <= k <=65535, 0 <= r <= 31)

 

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clawson wrote:
presumably something like this in the opcode manual

Indeed.

 

And that very manual explains what it means by "Rr" on its first page as shown in #3

 

EDIT

 

#3  - not #2

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
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Smajdalf wrote:
where comes the "r" from? "Source"?

Is that the real question - "why did they choose 'r' ?"

 

Who knows - and who cares !

 

It could be just any random letter to distinguish it from Rd ...

 

Remember that the AVR was invented by Norwegians - so, if there is a specific reason (which there need not be),  it might be based in Norwegian ...

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
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awneil wrote:
it might be based in Norwegian ...
My thoughts also. But I just checked Google translate and the Norwegian for "source" is "kilde" also it seems "source register" would be "kilderegister" but "source" is a word with a number of interpretations so maybe there are a number of potential words.

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awneil wrote:

Smajdalf wrote:
where comes the "r" from? "Source"?

Is that the real question - "why did they choose 'r' ?"

 

Who knows - and who cares !

 

It could be just any random letter to distinguish it from Rd ...

 

Remember that the AVR was invented by Norwegians - so, if there is a specific reason (which there need not be),  it might be based in Norwegian ...

Yes, this was the real question.

All other mnemonics seem to come from English and it is easy to imagine where they come from. I.e. CLR = Clear register, SER = Seregister. I just thought there is some other word starting with "r" they meant which I cannot find. If noone knows it probably has no meaning. Thank you.

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Smajdalf wrote:
it probably has no meaning.

Indeed.

 

Now please see Tip #5.

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillatorhttps://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
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I just had a read through the opcode manuals for other CPUs to see if anything else has similar naming schemes but most seem to use the slightly more obvious terms such as "src", "dst" and so on.

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Rread ?

Iluvatar is the better part of Valar.

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I always thought is was Rresource ......