setf8

Set Flags 8-bit

SETF8 <Wn>

Sets PSTATE flags based on 8-bit operand.

Pseudocode Operation

val8 ← Wn<7:0>; N ← val8<7>; Z ← (val8 == 0); C ← 0; V ← 0;

Example

SETF8 w1

Encoding

Binary Layout

0

31

0

30

1

29

11010000

28:21

000000

20:15

0

14

0010

13:10

Rn

9:5

0

4

1101

3:0

 

Format System

Opcode 0x3A00080D

Extension FEAT_FlagM

Operands

• Wn
  First source / base 32-bit integer register

Related

More in FEAT_FlagM

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0x3A00080D	SETF8 <Wn>		A64		0 | 0 | 1 | 11010000 | 000000 | 0 | 0010 | Rn | 0 | 1101

Description

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.

Operation

bits(32) tmpreg = X[n, 32];
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;