@scrypt-inc/bitcoinjs-lib
Version:
Client-side Bitcoin JavaScript library
106 lines (105 loc) • 3.65 kB
JavaScript
;
var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
var desc = Object.getOwnPropertyDescriptor(m, k);
if (!desc || ("get" in desc ? !m.__esModule : desc.writable || desc.configurable)) {
desc = { enumerable: true, get: function() { return m[k]; } };
}
Object.defineProperty(o, k2, desc);
}) : (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
o[k2] = m[k];
}));
var __setModuleDefault = (this && this.__setModuleDefault) || (Object.create ? (function(o, v) {
Object.defineProperty(o, "default", { enumerable: true, value: v });
}) : function(o, v) {
o["default"] = v;
});
var __importStar = (this && this.__importStar) || function (mod) {
if (mod && mod.__esModule) return mod;
var result = {};
if (mod != null) for (var k in mod) if (k !== "default" && Object.prototype.hasOwnProperty.call(mod, k)) __createBinding(result, mod, k);
__setModuleDefault(result, mod);
return result;
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.decode = decode;
exports.encode = encode;
const tools = __importStar(require("uint8array-tools"));
/**
* Decodes a script number from a buffer.
*
* @param buffer - The buffer containing the script number.
* @param maxLength - The maximum length of the script number. Defaults to 4.
* @param minimal - Whether the script number should be minimal. Defaults to true.
* @returns The decoded script number.
* @throws {TypeError} If the script number overflows the maximum length.
* @throws {Error} If the script number is not minimally encoded when minimal is true.
*/
function decode(buffer, maxLength, minimal) {
maxLength = maxLength || 4;
minimal = minimal === undefined ? true : minimal;
const length = buffer.length;
if (length === 0)
return 0;
if (length > maxLength)
throw new TypeError('Script number overflow');
if (minimal) {
if ((buffer[length - 1] & 0x7f) === 0) {
if (length <= 1 || (buffer[length - 2] & 0x80) === 0)
throw new Error('Non-minimally encoded script number');
}
}
// 40-bit
if (length === 5) {
const a = tools.readUInt32(buffer, 0, 'LE');
const b = tools.readUInt8(buffer, 4);
if (b & 0x80)
return -((b & ~0x80) * 0x100000000 + a);
return b * 0x100000000 + a;
}
// 32-bit / 24-bit / 16-bit / 8-bit
let result = 0;
for (let i = 0; i < length; ++i) {
result |= buffer[i] << (8 * i);
}
if (buffer[length - 1] & 0x80)
return -(result & ~(0x80 << (8 * (length - 1))));
return result;
}
function scriptNumSize(i) {
return i > 0x7fffffff
? 5
: i > 0x7fffff
? 4
: i > 0x7fff
? 3
: i > 0x7f
? 2
: i > 0x00
? 1
: 0;
}
/**
* Encodes a number into a Uint8Array using a specific format.
*
* @param _number - The number to encode.
* @returns The encoded number as a Uint8Array.
*/
function encode(_number) {
let value = Math.abs(_number);
const size = scriptNumSize(value);
const buffer = new Uint8Array(size);
const negative = _number < 0;
for (let i = 0; i < size; ++i) {
tools.writeUInt8(buffer, i, value & 0xff);
value >>= 8;
}
if (buffer[size - 1] & 0x80) {
tools.writeUInt8(buffer, size - 1, negative ? 0x80 : 0x00);
}
else if (negative) {
buffer[size - 1] |= 0x80;
}
return buffer;
}