PMULL, PMULL2
Polynomial multiply long
This instruction multiplies corresponding elements in the
lower or upper half of the vectors
of the two source SIMD&FP registers, places the results in a vector, and
writes the vector to the destination SIMD&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}.
The PMULL instruction extracts
each source vector from the lower half
of each source register. The PMULL2 instruction extracts
each source vector from the upper half
of each source register.
The PMULL and PMULL2 variants that operate on 64-bit source elements
are defined only when FEAT_PMULL is implemented.
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.
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.
0
0
0
1
1
1
0
1
1
1
1
0
0
0
PMULL{2} <Vd>.<Ta>, <Vn>.<Tb>, <Vm>.<Tb>
if size == '01' || size == '10' then UNDEFINED;
if size == '11' && !IsFeatureImplemented(FEAT_PMULL) then UNDEFINED;
constant integer d = UInt(Rd);
constant integer n = UInt(Rn);
constant integer m = UInt(Rm);
constant integer esize = 8 << UInt(size);
constant integer datasize = 64;
constant integer part = UInt(Q);
constant integer elements = datasize DIV esize;
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, and is
Q
2
0
[absent]
1
[present]
<Vd>
Is the name of the SIMD&FP destination register, encoded in the "Rd" field.
<Ta>
Is an arrangement specifier,
size
<Ta>
00
8H
01
RESERVED
10
RESERVED
11
1Q
The '1Q' arrangement is only allocated in an implementation that includes the Cryptographic Extension, and is otherwise RESERVED.
<Vn>
Is the name of the first SIMD&FP source register, encoded in the "Rn" field.
<Tb>
Is an arrangement specifier,
size
Q
<Tb>
00
0
8B
00
1
16B
01
x
RESERVED
10
x
RESERVED
11
0
1D
11
1
2D
<Vm>
Is the name of the second SIMD&FP source register, encoded in the "Rm" field.
CheckFPAdvSIMDEnabled64();
constant bits(datasize) operand1 = Vpart[n, part, datasize];
constant bits(datasize) operand2 = Vpart[m, part, datasize];
bits(2*datasize) result;
bits(esize) element1;
bits(esize) element2;
for e = 0 to elements-1
element1 = Elem[operand1, e, esize];
element2 = Elem[operand2, e, esize];
Elem[result, e, 2*esize] = PolynomialMult(element1, element2);
V[d, 2*datasize] = result;