Conditional select negation
This instruction returns, in the destination register, the value of the first source register if the condition is TRUE, and otherwise returns the negated value of the second source register.
This instruction is used by the alias CNEG.
| 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 |
| sf | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 0 | Rm | cond | 0 | 1 | Rn | Rd | |||||||||||||||
| op | S | o2 | |||||||||||||||||||||||||||||
let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); let m : integer{} = UInt(Rm); let datasize : integer{} = 32 << UInt(sf); let condition : bits(4) = cond;
| <Wd> |
Is the 32-bit name of the general-purpose destination register, encoded in the "Rd" field. |
| <Wn> |
Is the 32-bit name of the first general-purpose source register, encoded in the "Rn" field. |
| <Wm> |
Is the 32-bit name of the second general-purpose source register, encoded in the "Rm" field. |
| <Xd> |
Is the 64-bit name of the general-purpose destination register, encoded in the "Rd" field. |
| <Xn> |
Is the 64-bit name of the first general-purpose source register, encoded in the "Rn" field. |
| <Xm> |
Is the 64-bit name of the second general-purpose source register, encoded in the "Rm" field. |
| Alias | Is preferred when |
|---|---|
| CNEG | !(cond IN {'111x'}) && Rn == Rm |
var result : bits(datasize); if ConditionHolds(condition) then result = X{datasize}(n); else result = NOT(X{datasize}(m)) + 1; end; X{datasize}(d) = result;
This instruction is a data-independent-time instruction as described in About PSTATE.DIT.
2026-03_rel 2026-03-26 20:48:11
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