vneg

Vector Negate (VFP)

VNEG<c>.F32 <Sd>, <Sm>

Negates the value.

Details

Vector Negate (VFP) negates the value in Sm by inverting the sign bit and stores the result in Sd. This is a unary floating-point operation that follows IEEE 754 semantics, affecting only the sign bit and updating FPSCR exception flags but not ARM condition flags. Available in A32/T32 with VFP extension; execution is conditional based on the condition code suffix.

Pseudocode Operation

Sd ← FP_Negate(Sm)
FPSCR ← updated with floating-point exception flags

Example

VNEG.F32 s0, s2

Encoding

Binary Layout
cond
11101
D
11
0
001
Vd
10
10
0
1
M
0
Vm
 
Format VFP Unary
Opcode 0x0EB10A40
Extension VFP (Float)

Operands

  • Sd
    Destination 32-bit floating-point register
  • Sm
    Second source 32-bit floating-point 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]);