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## SUB (vector)

Subtract (vector). This instruction subtracts each vector element in the second source SIMD&FP register from the corresponding vector element in the first source SIMD&FP register, places 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

 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 1 1 1 1 1 1 0 size 1 Rm 1 0 0 0 0 1 Rn Rd U
```integer d = UInt(Rd);
integer n = UInt(Rn);
integer m = UInt(Rm);
if size != '11' then UNDEFINED;
integer esize = 8 << UInt(size);
integer datasize = esize;
integer elements = 1;
boolean sub_op = (U == '1');```

### Vector

 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 size 1 Rm 1 0 0 0 0 1 Rn Rd U
```integer d = UInt(Rd);
integer n = UInt(Rn);
integer m = UInt(Rm);
if size:Q == '110' then UNDEFINED;
integer esize = 8 << UInt(size);
integer datasize = if Q == '1' then 128 else 64;
integer elements = datasize DIV esize;
boolean sub_op = (U == '1');```

### Assembler Symbols

<V> Is a width specifier, encoded in size:
size <V>
0x RESERVED
10 RESERVED
11 D
 Is the number of the SIMD&FP destination register, in the "Rd" field.
 Is the number of the first SIMD&FP source register, encoded in the "Rn" field.
 Is the number of the second SIMD&FP source register, encoded in the "Rm" field.
 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
 Is the name of the first SIMD&FP source register, encoded in the "Rn" field.
 Is the name of the second SIMD&FP source register, encoded in the "Rm" field.

### Operation

```CheckFPAdvSIMDEnabled64();
bits(datasize) operand1 = V[n];
bits(datasize) operand2 = V[m];
bits(datasize) result;
bits(esize) element1;
bits(esize) element2;

for e = 0 to elements-1
element1 = Elem[operand1, e, esize];
element2 = Elem[operand2, e, esize];
if sub_op then
Elem[result, e, esize] = element1 - element2;
else
Elem[result, e, esize] = element1 + element2;

V[d] = result;```

### Operational information

If PSTATE.DIT is 1:

• The execution time of this instruction is independent of:
• The values of the data supplied in any of its registers.
• The values of the NZCV flags.
• The response of this instruction to asynchronous exceptions does not vary based on:
• The values of the data supplied in any of its registers.
• The values of the NZCV flags.