vneg

Vector Negate

VNEG<c>.<dt> <Qd>, <Qm>

Negates integer/float elements.

Details

Negates each element in the source vector and places the result in the destination register. For integer elements, the result is two's complement negation; for floating-point elements, only the sign bit is inverted. No condition flags are affected. Execution is available in both A32 and T32 instruction sets via NEON.

Pseudocode Operation

for i = 0 to elements-1
  Qd[i] ← -Qm[i]

Example

VNEG.dt q0, q2

Encoding

Binary Layout
111100111
D
11
size
01
Vd
0
F
111
0
M
0
Vm
 
Format NEON 2-Reg
Opcode 0xF3B10380
Extension NEON (SIMD)

Operands

  • Qd
    Destination 128-bit SIMD register
  • Qm
    Second source 128-bit SIMD register

Reference (Arm AArch32 ISA)

Instruction Forms

Encoding Instruction ISA Bit pattern
0xF3B10380 VNEG{<c>}{<q>}.<dt> <Dd>, <Dm> A32 111100111 | D | 11 | size | 01 | Vd | 0 | F | 111 | 0 | M | 0 | Vm
0xF3B103C0 VNEG{<c>}{<q>}.<dt> <Qd>, <Qm> A32 111100111 | D | 11 | size | 01 | Vd | 0 | F | 111 | 1 | M | 0 | Vm
0x0EB10940 VNEG{<c>}{<q>}.F16 <Sd>, <Sm> A32 cond | 11101 | D | 11 | 0 | 001 | Vd | 10 | 01 | 0 | 1 | M | 0 | Vm
0x0EB10A40 VNEG{<c>}{<q>}.F32 <Sd>, <Sm> A32 cond | 11101 | D | 11 | 0 | 001 | Vd | 10 | 10 | 0 | 1 | M | 0 | Vm
0x0EB10B40 VNEG{<c>}{<q>}.F64 <Dd>, <Dm> A32 cond | 11101 | D | 11 | 0 | 001 | Vd | 10 | 11 | 0 | 1 | M | 0 | Vm
0xFFB10380 VNEG{<c>}{<q>}.<dt> <Dd>, <Dm> T32 111111111 | D | 11 | size | 01 | Vd | 0 | F | 111 | 0 | M | 0 | Vm
0xFFB103C0 VNEG{<c>}{<q>}.<dt> <Qd>, <Qm> T32 111111111 | D | 11 | size | 01 | Vd | 0 | F | 111 | 1 | M | 0 | Vm
0xEEB10940 VNEG{<c>}{<q>}.F16 <Sd>, <Sm> T32 111011101 | D | 11 | 0 | 001 | Vd | 10 | 01 | 0 | 1 | M | 0 | Vm
0xEEB10A40 VNEG{<c>}{<q>}.F32 <Sd>, <Sm> T32 111011101 | D | 11 | 0 | 001 | Vd | 10 | 10 | 0 | 1 | M | 0 | Vm
0xEEB10B40 VNEG{<c>}{<q>}.F64 <Dd>, <Dm> T32 111011101 | D | 11 | 0 | 001 | Vd | 10 | 11 | 0 | 1 | M | 0 | Vm

Description

Vector Negate negates each element in a vector, and places the results in a second vector. The floating-point version only inverts the sign bit. Depending on settings in the CPACR, NSACR, HCPTR, and FPEXC registers, and the Security state and PE mode in which the instruction is executed, an attempt to execute the instruction might be undefined, or trapped to Hyp mode. For more information see Enabling Advanced SIMD and floating-point support.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();  CheckAdvSIMDOrVFPEnabled(TRUE, advsimd);
    if advsimd then  // Advanced SIMD instruction
        for r = 0 to regs-1
            for e = 0 to elements-1
                if floating_point then
                    Elem[D[d+r],e,esize] = FPNeg(Elem[D[m+r],e,esize]);
                else
                    result = -SInt(Elem[D[m+r],e,esize]);
                    Elem[D[d+r],e,esize] = result<esize-1:0>;
    else             // VFP instruction
        case esize of
            when 16 S[d] = Zeros(16) : FPNeg(S[m]<15:0>);
            when 32 S[d] = FPNeg(S[m]);
            when 64 D[d] = FPNeg(D[m]);