Module bignum

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

Custom arbitrary-precision number (bignum) implementation.

This is designed to avoid the heap allocation at expense of stack memory. The most used bignum type, Big32x40, is limited by 32 × 40 = 1,280 bits and will take at most 160 bytes of stack memory. This is more than enough for round-tripping all possible finite f64 values.

In principle it is possible to have multiple bignum types for different inputs, but we don’t do so to avoid the code bloat. Each bignum is still tracked for the actual usages, so it normally doesn’t matter.

Modules

tests 👻 Experimental

Macros

define_bignum 🔒 Experimental

impl_full_ops 🔒 Experimental

Structs

Big32x40Experimental

Stack-allocated arbitrary-precision (up to certain limit) integer.

Constants

SMALL_POW5 🔒 Experimental

Table of powers of 5 representable in digits. Specifically, the largest {u8, u16, u32} value that’s a power of five, plus the corresponding exponent. Used in mul_pow5.

Traits

FullOpsExperimental

Arithmetic operations required by bignums.

Type Aliases

Digit32Experimental

The digit type for Big32x40.