You copied the Doc URL to your clipboard.

# FCADD (vector)

Floating-point Complex Add.

### Syntax

``` FCADD Vd.T, Vn.T, Vm.T, #rotate ```

Where:

`Vd`
Is the name of the SIMD and FP destination register.
`T`
Is an arrangement specifier, and can be one of `4H`, `8H`, `2S`, `4S` or `2D`.
`Vn`
Is the name of the first SIMD and FP source register.
`Vm`
Is the name of the second SIMD and FP source register.
`rotate`
Is the rotation, and can be either `90` or `270`.

## Architectures supported (vector)

Supported in Arm®v8.3-A architecture and later.

## Usage

Floating-point Complex Add.

This instruction adds two source complex numbers from the `Vm` and the `Vn` vector registers and places the resulting complex number in the destination `Vd` vector register. The number of complex numbers that can be stored in the `Vm`, the `Vn`, and the `Vd` registers is calculated as the vector register size divided by the length of each complex number. These lengths are 16 for half-precision, 32 for single-precision, and 64 for double-precision. Each complex number is represented in a SIMP&FP register as a pair of elements with the imaginary part of the number being placed in the more significant element, and the real part of the number being placed in the less significant element. Both real and imaginary parts of the source and the resulting complex number are represented as floating-point values.

One of the two vector elements that are read from each of the numbers in the `Vm` source SIMD and FP register can be optionally negated based on the rotation value:

• If the rotation is 90, the odd-numbered vector elements are negated.
• If the rotation is 270, the even-numbered vector elements are negated.

This instruction can generate a floating-point exception. Depending on the settings in FPCR, the exception results in either a flag being set in FPSR or a synchronous exception being generated. For more information, see Floating-point exception traps in the Arm® Architecture Reference Manual Arm®v8, for Arm®v8‑A architecture profile.

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.