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PMULL, PMULL2 (vector)

Polynomial Multiply Long.

Syntax

PMULL{2} Vd.Ta, Vn.Tb, Vm.Tb

Where:

2
Is the second and upper half specifier. If present it causes the operation to be performed on the upper 64 bits of the registers holding the narrower elements. See <Q> in the Usage table.
Vd
Is the name of the SIMD and FP destination register.
Ta
Is an arrangement specifier, 8H.
Vn
Is the name of the first SIMD and FP source register.
Tb
Is an arrangement specifier, and can be one of the values shown in Usage.
Vm
Is the name of the second SIMD and FP source register.

Usage

Polynomial Multiply Long. This instruction multiplies corresponding elements in the lower or upper half of the vectors of the two source SIMD and FP registers, places the results in a vector, and writes the vector to the destination SIMD and FP register. The destination vector elements are twice as long as the elements that are multiplied.

For information about multiplying polynomials see Polynomial arithmetic over {0, 1} in the ARMv8-A Architecture Reference Manual.

The PMULL instruction extracts each source vector from the lower half of each source register, while the PMULL2 instruction extracts each source vector from the upper half of each 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.

The following table shows the valid specifier combinations:

Table 20-27 PMULL, PMULL2 (Vector) specifier combinations

<Q> Ta Tb
- 8H 8B
2 8H 16B
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