Specifications

For more information, refer to “Settings Managed by the Software Build Tools” in the "Nios II Software
Build Tools Reference" chapter of the Nios II Software Developer’s Handbook.
Note: Register the instruction-related exception handler as early as possible in function main(). This
allows you to handle abnormal condition during startup. You register an exception handler from
the alt_main() function.
For more information about alt_main(), refer to “Boot Sequence and Entry Point” in the "Developing
Programs Using the Hardware Abstraction Layer" chapter of the Nios II Software Developer’s Handbook.
Related Information
• Developing Programs Using the Hardware Abstraction Layer on page 6-1
• Nios II Software Build Tools Reference on page 15-1
Removing an Instruction-Related Exception Handler
To remove a registered instruction-related exception handler, your C code must call the
alt_instruction_exception_register() function, as follows:
alt_instruction_exception_register ( null, null );
When the HAL removes the instruction-related exception handler, it restores the default break/optional
trap logic.
Document Revision History for Exception Handling
Date Version Changes
May 2015 2015.05.14
• Maintenance release.
• Renamed to Nios II Classic.
May 2011 11.0.0
• Introduction of Qsys system integration tool
• Interrupt vector custom instruction only available with SOPC
Builder
February 2011 10.1.0 Removed “Referenced Documents” section.
July 2010 10.0.0 Maintenance release.
November 2009 9.1.0
• Described HAL support for external interrupt controller interface.
• Described HAL support for shadow register sets with external
interrupt controller interface.
• Described enhanced HAL interrupt API.
• Legacy HAL interrupt API deprecated.
• Removed information specific to the Nios II Integrated Develop‐
ment Environment (IDE).
March 2009 9.0.0
• Reorganized and updated information and terminology to clarify
role of Nios II Software Build Tools.
• Corrected minor typographical errors.
NII5V2
2015.05.14
Removing an Instruction-Related Exception Handler
8-35
Exception Handling
Altera Corporation
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