SABDL, SABDL2
Signed absolute difference long
This instruction subtracts the vector elements in the lower or upper half
of the second source SIMD&FP register from the corresponding vector elements
of the first source SIMD&FP register, places the absolute value of the results
into a vector, and writes the vector to the destination SIMD&FP register.
The destination vector elements are twice as long as the source vector elements.
The SABDL instruction extracts each source vector from
the lower half of each source register.
The SABDL2 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.
This instruction is a data-independent-time instruction as described in About PSTATE.DIT.
0
0
0
1
1
1
0
1
0
1
1
1
0
0
SABDL{2} <Vd>.<Ta>, <Vn>.<Tb>, <Vm>.<Tb>
if !IsFeatureImplemented(FEAT_AdvSIMD) then EndOfDecode(Decode_UNDEF); end;
if size == '11' then EndOfDecode(Decode_UNDEF); end;
let d : integer{} = UInt(Rd);
let n : integer{} = UInt(Rn);
let m : integer{} = UInt(Rm);
let esize : integer{} = 8 << UInt(size);
let datasize : integer{} = 64;
let part : integer = UInt(Q);
let elements : integer = 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.
AArch64_CheckFPAdvSIMDEnabled();
let operand1 : bits(datasize) = Vpart{}(n, part);
let operand2 : bits(datasize) = Vpart{}(m, part);
var result : bits(2*datasize) = Zeros{2*datasize};
var element1 : integer;
var element2 : integer;
var absdiff : bits(2*esize);
for e = 0 to elements-1 do
element1 = SInt(operand1[e*:esize]);
element2 = SInt(operand2[e*:esize]);
absdiff = Abs(element1-element2)[2*esize-1:0];
result[e*:(2*esize)] = result[e*:(2*esize)] + absdiff;
end;
V{2*datasize}(d) = result;
2026-03-26 20:27:25
2026-03_rel