text: var pushdata = require('pushdata-bitcoin')
  var varuint = require('varuint-bitcoin')
  
  // https://github.com/feross/buffer/blob/master/index.js#L1127
  function verifuint (value, max) {
    if (typeof value !== 'number') throw new Error('cannot write a non-number as a number')
    if (value < 0) throw new Error('specified a negative value for writing an unsigned value')
    if (value > max) {
      value = max;
      // throw new Error('RangeError: value out of range')
    }
    if (Math.floor(value) !== value) throw new Error('value has a fractional component')
  }
  
  function readUInt64LE (buffer, offset) {
    var a = buffer.readUInt32LE(offset)
    var b = buffer.readUInt32LE(offset + 4)
    b *= 0x100000000
  
    verifuint(b + a, 0x001fffffffffffff)
  
    return b + a
  }
  
  function writeUInt64LE (buffer, value, offset) {
    verifuint(value, 0x001fffffffffffff)
  
    buffer.writeInt32LE(value & -1, offset)
    buffer.writeUInt32LE(Math.floor(value / 0x100000000), offset + 4)
    return offset + 8
  }
  
  // TODO: remove in 4.0.0?
  function readVarInt (buffer, offset) {
    var result = varuint.decode(buffer, offset)
  
    return {
      number: result,
      size: varuint.decode.bytes
    }
  }
  
  // TODO: remove in 4.0.0?
  function writeVarInt (buffer, number, offset) {
    varuint.encode(number, buffer, offset)
    return varuint.encode.bytes
  }
  
  module.exports = {
    pushDataSize: pushdata.encodingLength,
    readPushDataInt: pushdata.decode,
    readUInt64LE: readUInt64LE,
    readVarInt: readVarInt,
    varIntBuffer: varuint.encode,
    varIntSize: varuint.encodingLength,
    writePushDataInt: pushdata.encode,
    writeUInt64LE: writeUInt64LE,
    writeVarInt: writeVarInt
  }
  