as: Xtensa Registers
9.54.2.2 Register Names
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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 'a0'...'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.
Info Catalog
as: Xtensa Opcodes
as: Xtensa Syntax