Created
January 31, 2024 06:16
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Convert between bigint and buffer
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import { expect, use } from 'chai' | |
import chaiAsPromised from 'chai-as-promised' | |
import { buffer2bigint, bigint2buffer } from '../src/bigint' | |
use(chaiAsPromised) | |
describe('Test Utils', () => { | |
before(async () => { | |
}) | |
it('test 0', async () => { | |
const value = 0 | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test -1', async () => { | |
const value = -1 | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test 1', async () => { | |
const value = 1 | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test bigint 0n', async () => { | |
const value = 0 | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test bigint -1n', async () => { | |
const value = -1n | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test bigint 1n', async () => { | |
const value = 1n | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test bigint 0x7f', async () => { | |
const value = 0x7f | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test bigint 0x7f+1', async () => { | |
const value = 0x7f+1 | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test bigint 0x7f-1', async () => { | |
const value = 0x7f-1 | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test bigint -0x7f', async () => { | |
const value = -0x7f | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test bigint 0xffffff', async () => { | |
const value = 0xffffff | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test bigint -0xffffff', async () => { | |
const value = -0xffffff | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test bigint max n', async () => { | |
const value = 1200n*10000n*10n**18n | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
it('test bigint neg n', async () => { | |
const value = -1200n*10000n*10n**18n | |
const buf = bigint2buffer(value) | |
console.log(buf.toString('hex')) | |
const result = buffer2bigint(buf) | |
console.log(result) | |
await expect(result).is.eq(BigInt(value)) | |
}) | |
}) |
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// Converts a bigint into a sign-magnitude representation | |
export function bigint2buffer(value: number | bigint): Buffer { | |
let hex = value < 0 ? (-value).toString(16) : value.toString(16); | |
if (hex.length % 2 !== 0) hex = "0" + hex; | |
const m = parseInt("0x" + hex.slice(0, 2), 16); | |
if (m >= 0x7f) { | |
hex = "00" + hex; | |
} | |
let buffer = Buffer.from(hex, "hex"); | |
if (value >= 0) { | |
return buffer; | |
} | |
for (let i = 0; i < buffer.length; i++) { | |
buffer[i] = ~buffer[i]!; | |
} | |
for (let i = buffer.length - 1; i >= 0; i--) { | |
if (buffer[i] === 0xff) { | |
buffer[i] = 0x00; | |
} else { | |
buffer[i]++; | |
break; | |
} | |
} | |
return buffer; | |
} | |
export function buffer2bigint(buffer: Buffer): bigint { | |
const isNegative = buffer[0]! & 0x80; | |
if (isNegative) { | |
let carry = true; | |
for (let i = buffer.length - 1; i >= 0; i--) { | |
buffer[i] = ~buffer[i]! & 0xff; | |
if (carry) { | |
carry = buffer[i] === 0xff; | |
buffer[i]++; | |
} | |
} | |
} | |
return ( | |
BigInt("0x" + buffer.toString("hex")) * | |
(isNegative ? BigInt(-1) : BigInt(1)) | |
); | |
} |
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