12.36 VEXT

Vector Extract.

Syntax

VEXT{cond}.8 {Qd}, Qn, Qm, #imm

VEXT{cond}.8 {Dd}, Dn, Dm, #imm

where:

cond

is an optional condition code.

Qd, Qn, Qm

specifies the destination register, the first operand register, and the second operand register, for a quadword operation.

Dd, Dn, Dm

specifies the destination register, the first operand register, and the second operand register, for a doubleword operation.

imm

is the number of 8-bit elements to extract from the bottom of the second operand vector, in the range 0-7 for doubleword operations, or 0-15 for quadword operations.

Operation

VEXT extracts 8-bit elements from the bottom end of the second operand vector and the top end of the first, concatenates them, and places the result in the destination vector. See the following figure for an example:

Figure 12-2 Operation of doubleword VEXT for imm = 3
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VEXT pseudo-instruction

You can specify a datatype of 16, 32, or 64 instead of 8. In this case, #imm refers to halfwords, words, or doublewords instead of referring to bytes, and the permitted ranges are correspondingly reduced.

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