nim-tommath

An High-Level wrapper of libtommath written in Nim.

import pkg/tommath
    
let a = initBigInt(10) # Load from regular int
let b = initBigInt("A", 16) # Load from string (Hex)
    
echo a + b # add
echo a * b # multiply
    
echo initBigInt("-99946744073709551615").toString(2) # Load from string (Decimal) and print as binary

Features

• Portable: This library compiles libtommath directly, so the end-user doesn't need to install it on the system.
• Open License: Unlike GMP, libtommath is under the public domain, which makes the distribution process less complicated.
• Performant: While there are native implementations of Big Integers in Nim, they are not fully optimized. This becomes important when we want to deal with very large numbers (2048+bits). This library instead uses fast algorithms that reduce the complexity of operations.
• Easy to use: An high-level interface is provided by default, which makes libtommath much easier to use.

Installing

Use nimble to install the library:

nimble install https://github.com/dadadani/nim-tommath

Accesing the low-level API

If you want to access the low-level API, you can use the raw module:

import pkg/tommath/raw

var mp: MpInt
discard mp_init_i64(addr mp, 2342543)

var mp2: MpInt
discard mp_init_i64(addr mp2, 1000000)

var mp3: MpInt
discard mp_init(addr mp3)

discard mp_add(addr mp, addr mp2, addr mp3)

var outp: string

var size: csize_t
discard mp_radix_size(addr mp3, 10, addr size)

outp.setLen(size-1)
discard mp_to_radix(addr mp3, cstring(outp), cint(size), nil, 10)

echo outp

mp_clear(addr mp)
mp_clear(addr mp2)
mp_clear(addr mp3)

Dynamic Linking

If you want to use the system's libtommath, compile your program with -d:useExternalTommath:

nim c -d:useExternalTommath myprogram.nim

Contributing

This wrapper is rather incomplete, so feel free to open pull requests if you are interested!