@lntools/buffer-cursor NPM

Buffer Cursor for simple reading/writing from a Buffer

Simplify reading and writing to buffers by internally maintaining the position. This library exposes a wrapper for a buffer that uses similar read and write methods to those found in the Node Buffer API. The library also includes methods that assist with reading Bitcoin specific encodings such as int64 and varuint. Large numbers are returned as BN.js values.

Usage:

npm install @lntools/buffer-cursor

const BufferCursor = require('@lntools/buffer-cursor');

let buffer = BufferCursor(Buffer.alloc(8));
buffer.writeUInt8(1);
buffer.writeUInt16BE(2);
buffer.writeUInt32BE(3);
buffer.writeBytes(Buffer.from([4]));
buffer.position = 0;
console.log(buffer.readUInt8());
console.log(buffer.readUInt16BE());
console.log(buffer.readUInt32BE());
console.log(buffer.readBytes());

API

position: number - the current buffer cursor position
eof: bool - whether the current position is at the end of the buffer
buffer: Buffer - the underlying buffer
lastReadBytes - number of bytes last read from the buffer
readUInt8(): number - reads 1 byte
readUInt16LE(): number - reads 2 bytes as 16-bit little-endian unsigned integer
readUInt16BE(): number - reads 2 bytes as 16-bit big-endian unsigned integer
readUInt32LE(): number - reads 4 bytes as 32-bit little-endian unsigned integer
readUInt32BE(): number - reads 4 bytes as 32-bit big-endian unsigned integer
readUInt64LE(): BN - reads 8 bytes as 64-bit little-endian unsigned integer
readUInt64BE(): BN - reads 8 bytes as 64-bit big-endian unsigned integer
readVarUint(): BN - reads a variable length integer as defined in the Bitcoin protocol docs
readBytes([len]): Buffer - reads the optionally specified number of bytes. If no length is supplied, it reads to the end of the buffer.
writeUInt8(number): undefined - writes 1 byte
writeUInt16LE(number): undefined - writes a number as a 16-bit little-endian unsigned integer
writeUInt16BE(number): undefined - writes a number as a 16-bit big-endian unsigned integer
writeUInt32LE(number): undefined - writes a number as a 32-bit little-endian unsigned integer
writeUInt32BE(number): undefined - writes a number as a 32-bit big-endian unsigned integer
writeUInt64LE(number): undefined - writes a number as a 64-bit little-endian unsigned integer
writeUInt64BE(number): undefined - writes a number as a 64-bit big-endian unsigned integer
writeBytes(buffer): undefined - writes the supplied buffer to the cursor buffer