You copied the Doc URL to your clipboard.

## FNEG (vector)

Floating-point Negate (vector). This instruction negates the value of each vector element in the source SIMD&FP register, writes the result to a vector, and writes the vector to the destination SIMD&FP 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.

It has encodings from 2 classes: Half-precision and Single-precision and double-precision

### Half-precision(Armv8.2)

 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 Q 1 0 1 1 1 0 1 1 1 1 1 0 0 0 1 1 1 1 1 0 Rn Rd U

#### Half-precision

FNEG <Vd>.<T>, <Vn>.<T>

```if !HaveFP16Ext() then UNDEFINED;

integer d = UInt(Rd);
integer n = UInt(Rn);

integer esize = 16;
integer datasize = if Q == '1' then 128 else 64;
integer elements = datasize DIV esize;
boolean neg = (U == '1');```

### Single-precision and double-precision

 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 Q 1 0 1 1 1 0 1 sz 1 0 0 0 0 0 1 1 1 1 1 0 Rn Rd U

#### Single-precision and double-precision

FNEG <Vd>.<T>, <Vn>.<T>

```integer d = UInt(Rd);
integer n = UInt(Rn);

if sz:Q == '10' then UNDEFINED;
integer esize = 32 << UInt(sz);
integer datasize = if Q == '1' then 128 else 64;
integer elements = datasize DIV esize;
boolean neg = (U == '1');```

### Assembler Symbols

 Is the name of the SIMD&FP destination register, encoded in the "Rd" field.
<T> For the half-precision variant: is an arrangement specifier, encoded in Q:
Q <T>
0 4H
1 8H
For the single-precision and double-precision variant: is an arrangement specifier, encoded in sz:Q:
sz Q <T>
0 0 2S
0 1 4S
1 0 RESERVED
1 1 2D
 Is the name of the SIMD&FP source register, encoded in the "Rn" field.

### Operation

```CheckFPAdvSIMDEnabled64();
bits(datasize) operand = V[n];
bits(datasize) result;
bits(esize) element;

for e = 0 to elements-1
element = Elem[operand, e, esize];
if neg then
element = FPNeg(element);
else
element = FPAbs(element);
Elem[result, e, esize] = element;

V[d] = result;```