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SETF8, SETF16

Set the PSTATE.NZV flags based on the value in the specified general-purpose register. SETF8 treats the value as an 8 bit value, and SETF16 treats the value as an 16 bit value.

The PSTATE.C flag is not affected by these instructions.

Integer
(Armv8.4)

313029282726252423222120191817161514131211109876543210
00111010000000000sz0010Rn01101
sf

SETF8 (sz == 0)

SETF8 <Wn>

SETF16 (sz == 1)

SETF16 <Wn>

if !HaveFlagManipulateExt() then UNDEFINED;
integer msb = if sz == '1' then 15 else 7;
integer n = UInt(Rn);

Assembler Symbols

<Wn>

Is the 32-bit name of the general-purpose source register, encoded in the "Rn" field.

Operation

bits(32) tmpreg = X[n];
PSTATE.N = tmpreg<msb>;
PSTATE.Z = if (tmpreg<msb:0> == Zeros(msb + 1)) then '1' else '0';
PSTATE.V = tmpreg<msb+1> EOR tmpreg<msb>;
//PSTATE.C unchanged;

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.
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