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janishyathi bonam
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Joined: 05 May 2020
Posts: 2
Location: USA
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Hi!
I'm trying to LA R1,5000 and it says invalid displacement. Is there a limit to the value of the second operand? How can I achieve this? |
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steve-myers
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Joined: 30 Nov 2013
Posts: 917
Location: The Universe
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Yes, there is a limit: 4095. There are at least three ways to achieve your goal.
- Two LA instructions, for example
| Code: |
LA R1,2500
LA R1,2500(,R1) |
Dinosaurs like me would use this solution. The actual immediate values can be anything that adds to 5000; they do not have be 2500.
LHI instruction
This solution uses just 4 bytes.
LGFI instruction
This is hidden in Principles of Operation, but the sign of the immediate value is extended to bits 0 through 31 of the register. This solution uses 6 bytes. |
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janishyathi bonam
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Joined: 05 May 2020
Posts: 2
Location: USA
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| Thank you!! |
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Ravi GA
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Joined: 20 Mar 2020
Posts: 12
Location: India
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| janishyathi bonam wrote: |
Hi!
I'm trying to LA R1,5000 and it says invalid displacement. Is there a limit to the value of the second operand? How can I achieve this? |
LAY R1,5000 is one more way to load values greater than 4095. |
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steve-myers
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Joined: 30 Nov 2013
Posts: 917
Location: The Universe
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| Ravi GA wrote: |
| ... LAY R1,5000 is one more way to load values greater than 4095. |
Yes, indeed. I had forgotten about LAY. I would suggest you read Principles of Operation very carefully before using it. |
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