Application Binary Interface Revision History - Intel NIOS II Owner Reference Manual

The object macro
for Nios II R1 ISA and is predefined to 2 when you compile for Nios II R2 ISA.

7.11. Application Binary Interface Revision History

Document
Version
2018.04.18 • Implemented editorial enhancements.
• Updated the information about object macros in Development Environment.
2016.10.28 Maintenance release.
2015.04.02 Initial release
Nios II Processor Reference Guide
168
is predefined to 1 when you compile a program
__nios2_arch__
7. Application Binary Interface
Changes
NII-PRG | 2018.04.18