The Thumb-2 Instruction Set


The "Cortex" (ARMv7) family introduced Thumb-2
It is a separate instruction decoder, not a decompressor any more
It is an extension of the previous Thumb machine code
It can access all registers
All core features can be accessed
New ITE instruction (if then else),

ARM defined a Unified Assembler Language
You can build the same source as ARM or Thumb instructions
The idea saves a lot of conditionals and unmaintained code
Unfortunately, it is not trivial 

It is now possible to build Thumb-only devices
Cortex-A (application processor) has both ARM and Thumb2
Cortex-M (microcontroller) only includes a Thumb2 decoder

This also required a change in the IRQ vectors
Not a problem when making incompatible changes anyways