SPNU151V January 1998 – February 2020
The ARM compiler reserves the name space of all identifiers beginning with an underscore ( _ ) or a dollar sign ($). In this dual-state support scheme, all 32-BIS state entry points begin with an underscore, and all 16-BIS state entry points begin with a dollar sign. All other compiler-generated identifiers, which are independent of the state of the processor, begin with an underscore. By this convention, all direct calls within a 16-bit function refer to the entry point beginning with a dollar sign and all direct calls within a 32-bit function refer to the entry point beginning with an underscore.