UXTL, UXTL2

Unsigned extend long

This instruction copies each vector element from the lower or upper half of the source SIMD&FP register into a vector, and writes the vector to the destination SIMD&FP register. The destination vector elements are twice as long as the source vector elements.

The UXTL instruction extracts vector elements from the lower half of the source register. The UXTL2 instruction extracts vector elements from the upper half of the source register.

Depending on the settings in the CPACR_EL1, CPTR_EL2, and CPTR_EL3 registers, and the current Security state and Exception level, an attempt to execute the instruction might be trapped.

Encoding: Vector

Variants: FEAT_AdvSIMD (ARMv8.0)

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0		1	0	1	1	1	1	0	!= 0000				0	0	0	1	0	1	0	0	1
	Q	U							immh				immb			opcode						Rn					Rd

UXTL{2} <Vd>.<Ta>, <Vn>.<Tb>

Equivalent to: USHLL{2} <Vd>.<Ta>, <Vn>.<Tb>, #0

Explanations

2: <Vd>: Is the name of the SIMD&FP destination register, encoded in the "Rd" field.
<Ta>: <Vn>: Is the name of the SIMD&FP source register, encoded in the "Rn" field.
<Tb>:

Operational Notes

If PSTATE.DIT is 1:

• The execution time of this instruction is independent of:
  • The values of the data supplied in any of its registers.
  • The values of the NZCV flags.
• The response of this instruction to asynchronous exceptions does not vary based on:
  • The values of the data supplied in any of its registers.
  • The values of the NZCV flags.