Struct Flags 

pub struct Flags {
    pub invalid: bool,
    pub div_by_zero: bool,
    pub overflow: bool,
    pub underflow: bool,
    pub inexact: bool,
}

The FCSR cause/flag bits an operation can raise (UM §7.2.2).

Completeness

All five are modeled for the four arithmetic operations, which compute through crate::softfloat and so have the exact pre-rounding result available. inexact and underflow were the two that previously never set for ordinary rounding — accuracy-ledger C-11 — and detecting them is precisely why that module exists.

Still not produced anywhere: the unmaskable unimplemented-operation cause (bit 17), which the VR4300 raises for subnormal operands and results. It is not an IEEE exception and is not part of this struct; see CAUSE_UNIMPLEMENTED.

Returned rather than written, because FCSR belongs to crate::cop1::Cop1Control and an arithmetic helper that reached into it would need to own it.

Fields

invalid: bool

Invalid operation — a signaling NaN, or an undefined form like 0 × ∞.

div_by_zero: bool

Division by zero, with a finite non-zero numerator.

overflow: bool

The result overflowed the format’s range.

underflow: bool

The result underflowed to a subnormal or zero.

inexact: bool

The result was not exactly representable.

Implementations

impl Flags

pub const NONE: Self

No exceptions raised.

pub const INVALID: Self

Just the invalid-operation flag.

pub const fn to_fcsr_bits(self) -> u32

Pack into the FCSR Cause bits 16..=12 and Flags bits 6..=2.

Both at once because hardware sets them together: Cause is what the current operation raised, Flags is the sticky accumulation.

Bit 17 (Unimplemented Operation) is not produced here — it is not an IEEE exception, and it is raised on its own by the conversions via CAUSE_UNIMPLEMENTED. Documenting the range as 17..=12 implied this helper could set it, which it cannot.

Trait Implementations

impl Clone for Flags

fn clone(&self) -> Flags

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Flags

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

Formats the value using the given formatter.

impl Default for Flags

fn default() -> Flags

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Flags

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Flags

fn eq(&self, other: &Flags) -> 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 Serialize for Flags

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Copy for Flags

impl Eq for Flags

impl StructuralPartialEq for Flags