Struct Decimal 

pub struct Decimal { /* private fields */ }

A 128-bit signed fixed-point decimal.

value = mantissa × 10^(-scale)

• mantissa: signed coefficient stored as i128
• scale: number of decimal places in [0, MAX_SCALE]

On-chain Borsh encoding: 17 bytes (16-byte LE mantissa + 1-byte scale).

Implementations

impl Decimal

pub fn checked_add(self, rhs: Decimal) -> Result<Decimal, ArithmeticError>

Checked addition. Aligns scales then adds mantissas.

pub fn checked_sub(self, rhs: Decimal) -> Result<Decimal, ArithmeticError>

Checked subtraction. Aligns scales then subtracts mantissas.

pub fn checked_mul(self, rhs: Decimal) -> Result<Decimal, ArithmeticError>

Checked multiplication: self * rhs.

Result scale = self.scale + rhs.scale. Returns Err(ScaleExceeded) if that exceeds MAX_SCALE.

pub fn checked_div(self, rhs: Decimal) -> Result<Decimal, ArithmeticError>

Checked division: self / rhs.

Scales the numerator up by MAX_SCALE - self.scale places before dividing to retain maximum precision.

pub fn checked_neg(self) -> Result<Decimal, ArithmeticError>

Negation: returns -self.

Fails with Err(Overflow) for Decimal::MIN (two’s-complement has no positive counterpart for i128::MIN).

pub fn checked_abs(self) -> Result<Decimal, ArithmeticError>

Absolute value: returns |self|.

Fails with Err(Overflow) for Decimal::MIN.

pub fn checked_mul_div( self, numerator: Decimal, denominator: Decimal, ) -> Result<Decimal, ArithmeticError>

Compound (self × numerator) / denominator with 256-bit intermediate.

Prevents silent overflow that occurs when self × numerator exceeds i128::MAX in a naive two-step mul then div.

impl Decimal

pub fn from_u64(v: u64) -> Self

Create a Decimal with scale 0 from a u64.

pub fn from_i64(v: i64) -> Self

Create a Decimal with scale 0 from an i64.

pub fn from_u128(v: u128) -> Result<Self, ArithmeticError>

Create a Decimal with scale 0 from a u128.

Returns Err(Overflow) if v > i128::MAX.

pub fn from_i128(v: i128) -> Self

Create a Decimal with scale 0 from an i128.

pub fn from_token_amount( amount: u64, decimals: u8, ) -> Result<Self, ArithmeticError>

Create a Decimal from a raw SPL token amount and the mint’s decimals.

from_token_amount(1_500_000, 6) represents 1.500000 USDC.

impl Decimal

pub fn to_i128_truncated(self) -> i128

Truncate toward zero and return the integer part as i128.

Decimal { mantissa: 157, scale: 2 } (= 1.57) → 1

pub fn to_u64_truncated(self) -> Result<u64, ArithmeticError>

Truncate toward zero and return the integer part as u64.

Returns Err(Overflow) if the value is negative or exceeds u64::MAX.

pub fn to_token_amount( self, decimals: u8, mode: RoundingMode, ) -> Result<u64, ArithmeticError>

Convert to a raw SPL token u64 amount with explicit rounding.

Rounds to decimals decimal places first, then converts to an integer.

impl Decimal

pub fn from_str_exact(s: &str) -> Result<Self, ArithmeticError>

Parse a decimal string into a Decimal.

Accepted formats:

• "123" → { mantissa: 123, scale: 0 }
• "1.23" → { mantissa: 123, scale: 2 }
• "-1.23" → { mantissa: -123, scale: 2 }
• "+1.23" → { mantissa: 123, scale: 2 }

Returns Err(ScaleExceeded) if there are more than 28 fractional digits, or Err(InvalidInput) for malformed strings.

impl Decimal

pub const ZERO: Self

Additive identity: 0 × 10^0.

pub const ONE: Self

Multiplicative identity: 1 × 10^0.

pub const MAX: Self

Maximum representable value: i128::MAX × 10^0.

pub const MIN: Self

Minimum representable value: i128::MIN × 10^0.

pub const NEG_ONE: Self

Negative one: -1 × 10^0.

pub const HUNDRED: Self

100 × 10^0 — useful for percentage arithmetic.

pub const TEN_THOUSAND: Self

10_000 × 10^0 — basis-points denominator.

pub fn new(mantissa: i128, scale: u8) -> Result<Self, ArithmeticError>

Construct a Decimal from a raw mantissa and scale.

Returns Err(ArithmeticError::ScaleExceeded) if scale > MAX_SCALE.

pub fn mantissa(self) -> i128

Returns the raw mantissa.

pub fn scale(self) -> u8

Returns the scale (number of decimal places).

pub fn is_zero(self) -> bool

Returns true if the value is exactly zero.

pub fn is_positive(self) -> bool

Returns true if the value is strictly positive.

pub fn is_negative(self) -> bool

Returns true if the value is strictly negative.

impl Decimal

pub fn round(self, dp: u8, mode: RoundingMode) -> Result<Self, ArithmeticError>

Round self to dp decimal places using the given rounding mode.

If dp >= self.scale no rounding is needed and self is returned unchanged (possibly with a different scale representation).

Errors

Returns Err(ScaleExceeded) if dp > MAX_SCALE.

pub fn rescale_up(self, new_scale: u8) -> Result<Self, ArithmeticError>

Rescale self to a higher number of decimal places by padding zeros.

Only increases scale; use round to decrease it. Returns Err(ScaleExceeded) if new_scale > MAX_SCALE or Err(Overflow) if the mantissa multiplication overflows.

Trait Implementations

impl Clone for Decimal

fn clone(&self) -> Decimal

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Decimal

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

Formats the value using the given formatter.

impl Default for Decimal

fn default() -> Decimal

Returns the “default value” for a type.

impl Display for Decimal

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

Formats the value using the given formatter.

impl Hash for Decimal

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 Ord for Decimal

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

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

where Self: Sized,

Compares and returns the maximum of two values.

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

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Decimal

fn eq(&self, other: &Decimal) -> 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 PartialOrd for Decimal

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for Decimal

impl Eq for Decimal

impl StructuralPartialEq for Decimal