Rotate, mask insert flags
This instruction performs a rotation right of a value held in a general-purpose register by an immediate value, and then inserts a selection of the bottom four bits of the result of the rotation into the PSTATE flags, under the control of a second immediate mask.
| 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 |
| 1 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | imm6 | 0 | 0 | 0 | 0 | 1 | Rn | 0 | mask | ||||||||||||
| sf | op | S | o2 | ||||||||||||||||||||||||||||
if !IsFeatureImplemented(FEAT_FlagM) then EndOfDecode(Decode_UNDEF); end; let imm : integer{} = UInt(imm6); let flagmask : bits(4) = mask; let n : integer{} = UInt(Rn);
| <Xn> |
Is the 64-bit name of the general-purpose source register, encoded in the "Rn" field. |
| <shift> |
Is the shift amount, in the range 0 to 63, defaulting to 0 and encoded in the "imm6" field. |
| <mask> |
Is the flag bit mask, an immediate in the range 0 to 15, which selects the bits that are inserted into the NZCV condition flags, encoded in the "mask" field. |
let reg : bits(64) = X{}(n); let flags : bits(4) = (reg::reg)[imm+3:imm]; if flagmask[3] == '1' then PSTATE.N = flags[3]; end; if flagmask[2] == '1' then PSTATE.Z = flags[2]; end; if flagmask[1] == '1' then PSTATE.C = flags[1]; end; if flagmask[0] == '1' then PSTATE.V = flags[0]; end;
This instruction is a data-independent-time instruction as described in About PSTATE.DIT.
2025-09_diff_tag 2025-11-28 16:29:05
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