@tokamak-zk-evm/synthesizer/src/tokamak/utils/utils.ts

Tokamak zk-EVM Synthesizer - Processes Ethereum transactions into wire maps for Tokamak zk-SNARK proof generation

import type { PlacementEntry, Placements } from '../types/index.js'

export const powMod = (base: bigint, exponent: bigint, modulus: bigint): bigint => {
  if (modulus === 1n) return 0n

  let result = 1n
  base = base % modulus

  while (exponent > 0n) {
    if (exponent % 2n === 1n) {
      result = (result * base) % modulus
    }
    base = (base * base) % modulus
    exponent = exponent >> 1n
  }
  return result
}

export const byteSize = (value: bigint): number => {
  const hexLength = value.toString(16).length
  return Math.max(Math.ceil(hexLength / 2), 1)
}

export const addPlacement = (map: Placements, value: PlacementEntry) => {
  const key = map.size
  map.set(key, value)
}

// Convert to signed integer (256-bit)
export const convertToSigned = (value: bigint): bigint => {
  const SIGN_BIT = 1n << 255n
  return (value & SIGN_BIT) !== 0n ? value - (1n << 256n) : value
}

// Debugging tool
export const mapToStr = (map: Map<any, any>) => {
  return Object.fromEntries(
    Array.from(map, ([key, value]) => [
      key,
      JSON.parse(JSON.stringify(value, (k, v) => (typeof v === 'bigint' ? v.toString() : v))),
    ]),
  )
}

// Debugging tool
export function arrToStr(key: string, value: any) {
  return typeof value === 'bigint' ? value.toString() : value
}

export function split256BitInteger(value: bigint): bigint[] {
  // Calculate the lower and upper parts
  const lower = (value & ((1n << 128n) - 1n)) % 2n ** 128n
  const upper = (value >> 128n) % 2n ** 128n

  return [lower, upper]
}

export const merge128BitIntegers = (low: bigint, high: bigint): bigint => {
  // assume the inputs are in 128bit (Todo: check the input validity)
  return (high << 128n) + low
}