dup

Duplicate Vector Element (Element)

DUP <Vd>.<T>, <Vn>.<Ts>[<index>]

Duplicates a vector element to all elements in destination.

Pseudocode Operation

element_size ← decode_element_size(imm5);
element ← Vn.<element_size>[index_from_imm5];
for i = 0 to (vector_length / element_size - 1)
  Vd.<element_size>[i] ← element;

Example

DUP v0.4s.T, v1.4s.Ts[index]

Encoding

Binary Layout

01110000

28:21

imm5

20:16

0000

14:11

9:5

4:0

Format SIMD Copy

Opcode 0x0E000400

Extension NEON (SIMD)

Operands

Vd
Destination SIMD/FP vector register
Vn
Src Vector
index
Index

Other forms of dup

dup Duplicate Vector Element (Scalar)
dup SVE Duplicate Scalar

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction	ISA	Bit pattern
0x5E000400	DUP <V><d>, <Vn>.<T>[<index>]	A64	01 \| 0 \| 11110000 \| imm5 \| 0 \| 0000 \| 1 \| Rn \| Rd
0x0E000400	DUP <Vd>.<T>, <Vn>.<Ts>[<index>]	A64	0 \| Q \| 0 \| 01110000 \| imm5 \| 0 \| 0000 \| 1 \| Rn \| Rd
0x0E000C00	DUP <Vd>.<T>, <R><n>	A64	0 \| Q \| 0 \| 01110000 \| imm5 \| 0 \| 0001 \| 1 \| Rn \| Rd
0x2538C000	DUP <Zd>.<T>, #<imm>{, <shift>}	A64	00100101 \| size \| 111 \| 0 \| 0 \| 011 \| sh \| imm8 \| Zd
0x05203800	DUP <Zd>.<T>, <R><n\|SP>	A64	00000101 \| size \| 100000001110 \| Rn \| Zd
0x05202000	DUP <Zd>.<T>, <Zn>.<T>[<imm>]	A64	00000101 \| imm2 \| 1 \| tsz \| 001000 \| Zn \| Zd

Description

Duplicate vector element to vector or scalar. This instruction duplicates the vector element at the specified element index in the source SIMD&FP register into a scalar or each element in a vector, and writes the result to the destination SIMD&FP 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.

Operation

CheckFPAdvSIMDEnabled64();
bits(idxdsize) operand = V[n, idxdsize];
bits(datasize) result;
bits(esize) element;

element = Elem[operand, index, esize];
for e = 0 to elements-1
    Elem[result, e, esize] = element;
V[d, datasize] = result;

dup