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3. Programming Model
NII-PRG | 2018.04.18
Related Information
•
Nios II Custom Instruction User Guide
•
Processor Architecture
3.9.9. No-Operation Instruction
The Nios II assembler provides a no-operation instruction,
3.9.10. Potential Unimplemented Instructions
Some Nios II processor cores do not support all instructions in hardware. In this case,
the processor generates an exception after issuing an unimplemented instruction. Only
the following instructions can generate an unimplemented instruction exception:
•
mul
•
muli
•
mulxss
•
mulxsu
•
mulxuu
•
div
•
divu
•
initda
All other instructions are guaranteed not to generate an unimplemented instruction
exception.
An exception routine must exercise caution if it uses these instructions, because they
could generate another exception before the previous exception is properly handled.
Refer to the "Unimplemented Instruction" section of this chapter for more information
regarding unimplemented instruction processing.
Related Information
Unimplemented Instruction
3.10. Programming Model Revision History
Document
Version
2018.04.18
•
Implemented editorial enhancements.
•
Corrected information about
•
Corrected the Table:MASK Region Size Encodings.
2016.10.28
Removed extra exception information option.
2015.04.02
Initial release
on page 14
on page 84
Changes
, and
register.
mpubase
mpuacc
.
nop
Nios II Processor Reference Guide
105
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