Struct StatusFlags 

pub struct StatusFlags(/* private fields */);

CPU Status Register Flags (P register)

The status register contains flags that reflect the state of the CPU and control certain behaviors like interrupt handling.

Flag Bits (NV-BDIZC)

• N (Negative): Set if result is negative (bit 7 = 1)
• V (Overflow): Set if signed overflow occurred
• U (Unused): Always 1 when pushed to stack
• B (Break): Distinguishes BRK from IRQ (stack only)
• D (Decimal): Decimal mode flag (ignored on NES)
• I (Interrupt Disable): When set, IRQ interrupts are masked
• Z (Zero): Set if result is zero
• C (Carry): Set if carry/borrow occurred

Example

use rustynes_cpu::StatusFlags;

let mut flags = StatusFlags::default();
flags.insert(StatusFlags::CARRY);
assert!(flags.contains(StatusFlags::CARRY));

// Set N and Z based on a value
let value = 0x00;
flags.set_zn(value);
assert!(flags.contains(StatusFlags::ZERO));
assert!(!flags.contains(StatusFlags::NEGATIVE));

Implementations

impl StatusFlags

pub const CARRY: Self

Carry flag (bit 0)

pub const ZERO: Self

Zero flag (bit 1)

pub const INTERRUPT_DISABLE: Self

Interrupt Disable flag (bit 2)

pub const DECIMAL: Self

Decimal Mode flag (bit 3) - ignored on NES but still functional

pub const BREAK: Self

Break flag (bit 4) - only set when pushed to stack from PHP/BRK

pub const UNUSED: Self

Unused flag (bit 5) - always 1 when pushed to stack

pub const OVERFLOW: Self

Overflow flag (bit 6)

pub const NEGATIVE: Self

Negative flag (bit 7)

impl StatusFlags

pub const fn empty() -> Self

Get a flags value with all bits unset.

pub const fn all() -> Self

Get a flags value with all known bits set.

pub const fn bits(&self) -> u8

Get the underlying bits value.

The returned value is exactly the bits set in this flags value.

pub const fn from_bits(bits: u8) -> Option<Self>

Convert from a bits value.

This method will return None if any unknown bits are set.

pub const fn from_bits_truncate(bits: u8) -> Self

Convert from a bits value, unsetting any unknown bits.

pub const fn from_bits_retain(bits: u8) -> Self

Convert from a bits value exactly.

pub fn from_name(name: &str) -> Option<Self>

Get a flags value with the bits of a flag with the given name set.

This method will return None if name is empty or doesn’t correspond to any named flag.

pub const fn is_empty(&self) -> bool

Whether all bits in this flags value are unset.

pub const fn is_all(&self) -> bool

Whether all known bits in this flags value are set.

pub const fn intersects(&self, other: Self) -> bool

Whether any set bits in a source flags value are also set in a target flags value.

pub const fn contains(&self, other: Self) -> bool

Whether all set bits in a source flags value are also set in a target flags value.

pub fn insert(&mut self, other: Self)

The bitwise or (|) of the bits in two flags values.

pub fn remove(&mut self, other: Self)

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. remove won’t truncate other, but the ! operator will.

pub fn toggle(&mut self, other: Self)

The bitwise exclusive-or (^) of the bits in two flags values.

pub fn set(&mut self, other: Self, value: bool)

Call insert when value is true or remove when value is false.

pub const fn intersection(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

pub const fn union(self, other: Self) -> Self

The bitwise or (|) of the bits in two flags values.

pub const fn difference(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

pub const fn symmetric_difference(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

pub const fn complement(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

impl StatusFlags

pub const fn iter(&self) -> Iter<StatusFlags>

Yield a set of contained flags values.

Each yielded flags value will correspond to a defined named flag. Any unknown bits will be yielded together as a final flags value.

pub const fn iter_names(&self) -> IterNames<StatusFlags>

Yield a set of contained named flags values.

This method is like iter, except only yields bits in contained named flags. Any unknown bits, or bits not corresponding to a contained flag will not be yielded.

impl StatusFlags

pub fn set_zn(&mut self, value: u8)

Update Zero and Negative flags based on a value

Arguments

• value - The 8-bit value to test

Flag Behavior

• Z is set if value == 0
• N is set if value & 0x80 != 0 (bit 7 set)

Example

use rustynes_cpu::StatusFlags;

let mut flags = StatusFlags::default();

flags.set_zn(0x00);
assert!(flags.contains(StatusFlags::ZERO));
assert!(!flags.contains(StatusFlags::NEGATIVE));

flags.set_zn(0x80);
assert!(!flags.contains(StatusFlags::ZERO));
assert!(flags.contains(StatusFlags::NEGATIVE));

pub fn to_stack_byte(&self, brk: bool) -> u8

Convert status to byte for pushing to stack

When status is pushed to stack (PHP, BRK, interrupts), the U bit is always set and the B bit depends on the source.

Arguments

• brk - If true, set B flag (from BRK/PHP). If false, clear B flag (from IRQ/NMI)

Returns

8-bit value with U=1 and B set according to brk

Example

use rustynes_cpu::StatusFlags;

let flags = StatusFlags::CARRY | StatusFlags::ZERO;

// From BRK/PHP: B=1, U=1
let stack_byte_brk = flags.to_stack_byte(true);
assert_eq!(stack_byte_brk & 0b0011_0000, 0b0011_0000);

// From IRQ/NMI: B=0, U=1
let stack_byte_int = flags.to_stack_byte(false);
assert_eq!(stack_byte_int & 0b0011_0000, 0b0010_0000);

pub fn from_stack_byte(byte: u8) -> Self

Convert byte from stack to status flags

When pulling status from stack (PLP, RTI), the B flag is ignored and U is always set.

Arguments

• byte - The 8-bit value pulled from stack

Returns

StatusFlags with U=1 and other flags set from byte

Example

use rustynes_cpu::StatusFlags;

// Stack byte with B=1 (from BRK)
let stack_byte = 0b0011_0011; // B=1, U=1, C=1, Z=1
let flags = StatusFlags::from_stack_byte(stack_byte);

// B flag is ignored when pulling from stack
assert!(!flags.contains(StatusFlags::BREAK));
// U is always set
assert!(flags.contains(StatusFlags::UNUSED));
// Other flags preserved
assert!(flags.contains(StatusFlags::CARRY));
assert!(flags.contains(StatusFlags::ZERO));

Trait Implementations

impl Binary for StatusFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl BitAnd for StatusFlags

fn bitand(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

type Output = StatusFlags

The resulting type after applying the & operator.

impl BitAndAssign for StatusFlags

fn bitand_assign(&mut self, other: Self)

The bitwise and (&) of the bits in two flags values.

impl BitOr for StatusFlags

fn bitor(self, other: StatusFlags) -> Self

The bitwise or (|) of the bits in two flags values.

type Output = StatusFlags

The resulting type after applying the | operator.

impl BitOrAssign for StatusFlags

fn bitor_assign(&mut self, other: Self)

The bitwise or (|) of the bits in two flags values.

impl BitXor for StatusFlags

fn bitxor(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

type Output = StatusFlags

The resulting type after applying the ^ operator.

impl BitXorAssign for StatusFlags

fn bitxor_assign(&mut self, other: Self)

The bitwise exclusive-or (^) of the bits in two flags values.

impl Clone for StatusFlags

fn clone(&self) -> StatusFlags

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StatusFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for StatusFlags

fn default() -> Self

Creates status register with default power-on state

Default state: Interrupt Disable = 1, Unused = 1

impl Extend<StatusFlags> for StatusFlags

fn extend<T: IntoIterator<Item = Self>>(&mut self, iterator: T)

The bitwise or (|) of the bits in each flags value.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl Flags for StatusFlags

const FLAGS: &'static [Flag<StatusFlags>]

The set of defined flags.

type Bits = u8

The underlying bits type.

fn bits(&self) -> u8

Get the underlying bits value.

fn from_bits_retain(bits: u8) -> StatusFlags

Convert from a bits value exactly.

fn empty() -> Self

Get a flags value with all bits unset.

fn all() -> Self

Get a flags value with all known bits set.

fn contains_unknown_bits(&self) -> bool

This method will return true if any unknown bits are set.

fn from_bits(bits: Self::Bits) -> Option<Self>

Convert from a bits value.

fn from_bits_truncate(bits: Self::Bits) -> Self

Convert from a bits value, unsetting any unknown bits.

fn from_name(name: &str) -> Option<Self>

Get a flags value with the bits of a flag with the given name set.

fn iter(&self) -> Iter<Self>

Yield a set of contained flags values.

fn iter_names(&self) -> IterNames<Self>

Yield a set of contained named flags values.

fn iter_defined_names() -> IterDefinedNames<Self>

Yield a set of all named flags defined by [Self::FLAGS].

fn is_empty(&self) -> bool

Whether all bits in this flags value are unset.

fn is_all(&self) -> bool

Whether all known bits in this flags value are set.

fn intersects(&self, other: Self) -> bool

where Self: Sized,

Whether any set bits in a source flags value are also set in a target flags value.

fn contains(&self, other: Self) -> bool

where Self: Sized,

Whether all set bits in a source flags value are also set in a target flags value.

fn truncate(&mut self)

where Self: Sized,

Remove any unknown bits from the flags.

fn insert(&mut self, other: Self)

where Self: Sized,

The bitwise or (|) of the bits in two flags values.

fn remove(&mut self, other: Self)

where Self: Sized,

The intersection of a source flags value with the complement of a target flags value (&!).

fn toggle(&mut self, other: Self)

where Self: Sized,

The bitwise exclusive-or (^) of the bits in two flags values.

fn set(&mut self, other: Self, value: bool)

where Self: Sized,

Call [Flags::insert] when value is true or [Flags::remove] when value is false.

fn clear(&mut self)

where Self: Sized,

Unsets all bits in the flags.

fn intersection(self, other: Self) -> Self

The bitwise and (&) of the bits in two flags values.

fn union(self, other: Self) -> Self

The bitwise or (|) of the bits in two flags values.

fn difference(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

fn symmetric_difference(self, other: Self) -> Self

The bitwise exclusive-or (^) of the bits in two flags values.

fn complement(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

impl FromIterator<StatusFlags> for StatusFlags

fn from_iter<T: IntoIterator<Item = Self>>(iterator: T) -> Self

The bitwise or (|) of the bits in each flags value.

impl Hash for StatusFlags

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl IntoIterator for StatusFlags

type Item = StatusFlags

The type of the elements being iterated over.

type IntoIter = Iter<StatusFlags>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl LowerHex for StatusFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Not for StatusFlags

fn not(self) -> Self

The bitwise negation (!) of the bits in a flags value, truncating the result.

type Output = StatusFlags

The resulting type after applying the ! operator.

impl Octal for StatusFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for StatusFlags

fn eq(&self, other: &StatusFlags) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PublicFlags for StatusFlags

type Primitive = u8

The type of the underlying storage.

type Internal = InternalBitFlags

The type of the internal field on the generated flags type.

impl Sub for StatusFlags

fn sub(self, other: Self) -> Self

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

type Output = StatusFlags

The resulting type after applying the - operator.

impl SubAssign for StatusFlags

fn sub_assign(&mut self, other: Self)

The intersection of a source flags value with the complement of a target flags value (&!).

This method is not equivalent to self & !other when other has unknown bits set. difference won’t truncate other, but the ! operator will.

impl UpperHex for StatusFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Copy for StatusFlags

impl Eq for StatusFlags

impl StructuralPartialEq for StatusFlags