You copied the Doc URL to your clipboard.


Atomic add on halfword in memory, without return.


STADDH Ws, [Xn|SP] ; No memory ordering general registers

STADDLH Ws, [Xn|SP] ; Release general registers


Is the 32-bit name of the general-purpose register holding the data value to be operated on with the contents of the memory location.
Is the 64-bit name of the general-purpose base register or stack pointer.

Architectures supported

Supported in ARMv8.1 and later.


Atomic add on halfword in memory, without return, atomically loads a 16-bit halfword from memory, adds the value held in a register to it, and stores the result back to memory.

  • STADDH has no memory ordering semantics.
  • STADDLH stores to memory with release semantics, as described in Load-Acquire, Store-Release.

For information about memory accesses see Load/Store addressing modes in the ARM Architecture Reference Manual ARMv8, for ARMv8-A architecture profile.