The assembly syntax for a register file entry is the short name for a TIE register file followed by the index into that register file. For example, the general-purpose
AR register file has a short name of
a, so these registers are named
a15. As a special feature,
sp is also supported as a synonym for
a1. Additional registers may be added by processor configuration options and by designer-defined TIE extensions. An initial $ character is optional in all register names.