@tonsdk/core

TVM arithmetic primitives and cell utilities for TON blockchain. Replicates exact TVM integer arithmetic for off-chain verification.

Why?

@ton/core uses JavaScript BigInt which doesn't exactly match TVM's 257-bit integer semantics. When verifying on-chain calculations off-chain (fee estimation, DEX math, staking rewards), you need exact arithmetic matching.

Installation

npm install @tonsdk/core

Arithmetic

import { muldiv, muldivfloor, muldivmod, TVMArithmetic } from '@tonsdk/core';

// TVM MULDIV - (x * y) / z with 514-bit intermediate precision
const result = muldiv(1000000000000000000n, 500n, 1000n);

// Floor division (toward negative infinity)
const floored = muldivfloor(amount, rate, 1000000000n);

// Quotient and remainder
const [quot, rem] = muldivmod(x, y, z);

// Stateful arithmetic with overflow checking
const tvm = new TVMArithmetic({ checkOverflow: true });
const safe = tvm.muldiv(a, b, c);

Fee Calculation

Matches TVM GETGASFEE / GETFORWARDFEE / STORAGEFEES exactly:

import { computeGasFee, computeForwardFee, computeStorageFee } from '@tonsdk/core';

// Gas fee for transaction
const gasFee = computeGasFee(50000, { gasPrice: 1000n });

// Forward fee for internal message
const fwdFee = computeForwardFee(3, 1024, {
  lumpPrice: 10000000n,
  cellPrice: 100n,
  bitPrice: 1n
});

// Storage fee
const storageFee = computeStorageFee(10, 8192, 86400);

Cell Inspection

import { inspectCell } from '@tonsdk/core';

const tree = inspectCell(cell);
// { bits: 256, refs: 2, hash: '...', children: [...] }

Use Cases

• DEX verification: Replicate AMM/stableswap math off-chain
• Fee estimation: Exact fee calculation before sending
• Testing: Verify contract arithmetic matches expectations
• Auditing: Check on-chain calculations in tooling

License

MIT