bitcoinjs-lib/src/cjs/push_data.cjs

Client-side Bitcoin JavaScript library

'use strict';
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];
      });
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  (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.encodingLength = encodingLength;
exports.encode = encode;
exports.decode = decode;
const ops_js_1 = require('./ops.cjs');
const tools = __importStar(require('uint8array-tools'));
/**
 * Calculates the encoding length of a number used for push data in Bitcoin transactions.
 * @param i The number to calculate the encoding length for.
 * @returns The encoding length of the number.
 */
function encodingLength(i) {
  return i < ops_js_1.OPS.OP_PUSHDATA1
    ? 1
    : i <= 0xff
      ? 2
      : i <= 0xffff
        ? 3
        : 5;
}
/**
 * Encodes a number into a buffer using a variable-length encoding scheme.
 * The encoded buffer is written starting at the specified offset.
 * Returns the size of the encoded buffer.
 *
 * @param buffer - The buffer to write the encoded data into.
 * @param num - The number to encode.
 * @param offset - The offset at which to start writing the encoded buffer.
 * @returns The size of the encoded buffer.
 */
function encode(buffer, num, offset) {
  const size = encodingLength(num);
  // ~6 bit
  if (size === 1) {
    tools.writeUInt8(buffer, offset, num);
    // 8 bit
  } else if (size === 2) {
    tools.writeUInt8(buffer, offset, ops_js_1.OPS.OP_PUSHDATA1);
    tools.writeUInt8(buffer, offset + 1, num);
    // 16 bit
  } else if (size === 3) {
    tools.writeUInt8(buffer, offset, ops_js_1.OPS.OP_PUSHDATA2);
    tools.writeUInt16(buffer, offset + 1, num, 'LE');
    // 32 bit
  } else {
    tools.writeUInt8(buffer, offset, ops_js_1.OPS.OP_PUSHDATA4);
    tools.writeUInt32(buffer, offset + 1, num, 'LE');
  }
  return size;
}
/**
 * Decodes a buffer and returns information about the opcode, number, and size.
 * @param buffer - The buffer to decode.
 * @param offset - The offset within the buffer to start decoding.
 * @returns An object containing the opcode, number, and size, or null if decoding fails.
 */
function decode(buffer, offset) {
  const opcode = tools.readUInt8(buffer, offset);
  let num;
  let size;
  // ~6 bit
  if (opcode < ops_js_1.OPS.OP_PUSHDATA1) {
    num = opcode;
    size = 1;
    // 8 bit
  } else if (opcode === ops_js_1.OPS.OP_PUSHDATA1) {
    if (offset + 2 > buffer.length) return null;
    num = tools.readUInt8(buffer, offset + 1);
    size = 2;
    // 16 bit
  } else if (opcode === ops_js_1.OPS.OP_PUSHDATA2) {
    if (offset + 3 > buffer.length) return null;
    num = tools.readUInt16(buffer, offset + 1, 'LE');
    size = 3;
    // 32 bit
  } else {
    if (offset + 5 > buffer.length) return null;
    if (opcode !== ops_js_1.OPS.OP_PUSHDATA4)
      throw new Error('Unexpected opcode');
    num = tools.readUInt32(buffer, offset + 1, 'LE');
    size = 5;
  }
  return {
    opcode,
    number: num,
    size,
  };
}