NEG (vector)

Negate (vector). This instruction reads each vector element from the source SIMD&FP register, negates each value, puts the result into 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: Scalar and Vector

Scalar

313029282726252423222120191817161514131211109876543210
0111111011100000101110RnRd
Usizeopcode

NEG D<d>, D<n>

integer d = UInt(Rd); integer n = UInt(Rn); if size != '11' then UNDEFINED; constant integer esize = 8 << UInt(size); constant integer datasize = esize; integer elements = 1; boolean neg = (U == '1');

Vector

313029282726252423222120191817161514131211109876543210
0Q101110size100000101110RnRd
Uopcode

NEG <Vd>.<T>, <Vn>.<T>

integer d = UInt(Rd); integer n = UInt(Rn); if size:Q == '110' then UNDEFINED; constant integer esize = 8 << UInt(size); constant integer datasize = 64 << UInt(Q); integer elements = datasize DIV esize; boolean neg = (U == '1');

Assembler Symbols

<d>

Is the number of the SIMD&FP destination register, encoded in the "Rd" field.

<n>

Is the number of the SIMD&FP source register, encoded in the "Rn" field.

<Vd>

Is the name of the SIMD&FP destination register, encoded in the "Rd" field.

<T>

Is an arrangement specifier, encoded in size:Q:

size Q <T>
00 0 8B
00 1 16B
01 0 4H
01 1 8H
10 0 2S
10 1 4S
11 0 RESERVED
11 1 2D
<Vn>

Is the name of the SIMD&FP source register, encoded in the "Rn" field.

Operation

CheckFPAdvSIMDEnabled64(); bits(datasize) operand = V[n, datasize]; bits(datasize) result; integer element; for e = 0 to elements-1 element = SInt(Elem[operand, e, esize]); if neg then element = -element; else element = Abs(element); Elem[result, e, esize] = element<esize-1:0>; V[d, datasize] = result;

Operational information

If PSTATE.DIT is 1:


Internal version only: aarchmrs v2023-12_rel, pseudocode v2023-12_rel, sve v2023-12_rel ; Build timestamp: 2023-12-15T16:46

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