dsc/bitstring.js

Read and write packed binary strings, bit-by-bit, in JavaScript

bitstring.js's Issues

Can't write fields of size>31

When you call .writebits(n, size) with size > 31, the operation fails silently. This is because JS casts all numbers to Int32's under-the-hood whenever bitwise operations are invoked, such as the following line in writebits:

bits = this._spill << size | n;

.bin() doesn't output leading zeros

While the internal representation appears to be correct, calling .bin() doesn't output the leading zeros for a given byte. For example,

var bits = new BitString();
bits.writebits(1,3);
bits.bin();

outputs "100000" rather than "00100000"

Can't read long bit length

Just as in Issue #4, JS 32-bit limitations for bitwise operations prevent reading bit lengths greater than 31 bits because of the following section of .readbits():

    while (size < n) {
      byte = this._nextbyte();
      if (byte == null) {
        break;
      }
      size += 8;
      // This is the problematic line, since the bitshift value accumulates within the `while` loop
      bits = bits << 8 | byte;
    }

.peek() on last byte moves position to start of buffer

When you call .peek() while the this._pos == this.buf.length, the relative seek line in the peek definition results in reseting this._pos to zero.