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Atomic add on byte in memory, without return.


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

STADDLB 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 the Arm®v8.1 architecture and later.


Atomic add on byte in memory, without return, atomically loads an 8-bit byte from memory, adds the value held in a register to it, and stores the result back to memory.

  • STADDB has no memory ordering semantics.
  • STADDLB 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 Arm®v8, for Arm®v8‑A architecture profile.