SMULL, SMULL2 (vector)
Signed multiply long (vector)
This instruction multiplies corresponding signed integer values 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.
The SMULL instruction extracts
each source vector from the lower half
of each source register. The SMULL2 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.
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
0
0
0
0
SMULL{2} <Vd>.<Ta>, <Vn>.<Tb>, <Vm>.<Tb>
if size == '11' 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
4S
10
2D
11
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
0
4H
01
1
8H
10
0
2S
10
1
4S
11
x
RESERVED
<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;
integer element1;
integer element2;
for e = 0 to elements-1
element1 = SInt(Elem[operand1, e, esize]);
element2 = SInt(Elem[operand2, e, esize]);
Elem[result, e, 2*esize] = (element1 * element2)<2*esize-1:0>;
V[d, 2*datasize] = result;