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The THUMBX directive instructs the assembler to interpret subsequent instructions as ThumbEE instructions, using the UAL syntax.



In files that contain code using different instruction sets, THUMBX must precede ThumbEE code written in UAL syntax.

If necessary, this directive also inserts one byte of padding to align to the next halfword boundary.

This directive does not assemble to any instructions. It also does not change the state. It only instructs the assembler to assemble ThumbEE instructions, and inserts padding if necessary.


  • ARM deprecates the use of ThumbEE instructions.
  • For descriptions of ThumbEE instructions, see the ARM Architecture Reference Manual.