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# NZCV, Condition Flags

The NZCV characteristics are:

## Purpose

Allows access to the condition flags.

## Configuration

## Attributes

NZCV is a 64-bit register.

## Field descriptions

The NZCV bit assignments are:

63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32
RES0
N | Z | C | V | RES0
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

#### Bits [63:32]

Reserved, RES0.

#### N, bit [31]

Negative condition flag. Set to 1 if the result of the last flag-setting instruction was negative.

#### Z, bit [30]

Zero condition flag. Set to 1 if the result of the last flag-setting instruction was zero, and to 0 otherwise. A result of zero often indicates an equal result from a comparison.

#### C, bit [29]

Carry condition flag. Set to 1 if the last flag-setting instruction resulted in a carry condition, for example an unsigned overflow on an addition.

#### V, bit [28]

Overflow condition flag. Set to 1 if the last flag-setting instruction resulted in an overflow condition, for example a signed overflow on an addition.

#### Bits [27:0]

Reserved, RES0.

## Accessing the NZCV

Accesses to this register use the following encodings:

#### MRS <Xt>, NZCV

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b11 | 0b011 | 0b0100 | 0b0010 | 0b000

if PSTATE.EL == EL0 then return Zeros(32):PSTATE.<N,Z,C,V>:Zeros(28); elsif PSTATE.EL == EL1 then return Zeros(32):PSTATE.<N,Z,C,V>:Zeros(28); elsif PSTATE.EL == EL2 then return Zeros(32):PSTATE.<N,Z,C,V>:Zeros(28); elsif PSTATE.EL == EL3 then return Zeros(32):PSTATE.<N,Z,C,V>:Zeros(28);

#### MSR NZCV, <Xt>

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b11 | 0b011 | 0b0100 | 0b0010 | 0b000

if PSTATE.EL == EL0 then PSTATE.<N,Z,C,V> = X[t]<31:28>; elsif PSTATE.EL == EL1 then PSTATE.<N,Z,C,V> = X[t]<31:28>; elsif PSTATE.EL == EL2 then PSTATE.<N,Z,C,V> = X[t]<31:28>; elsif PSTATE.EL == EL3 then PSTATE.<N,Z,C,V> = X[t]<31:28>;

AArch32 Registers | AArch64 Registers | AArch32 Instructions | AArch64 Instructions | Index by Encoding | External Registers | External Registers by Offset | Registers by Functional Group | Proprietary Notice

27/03/2019 21:59; e5e4db499bf9867a4b93324c4dbac985d3da9376

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