string_bits gem

Ruby's String is already a byte sequence. This gem extends it one level lower: a bit sequence --- making packed binary buffers first-class values without any new class.

The methods are designed for real workloads: Apache Arrow validity bitmaps, bitmap font glyph data, and any protocol buffer where bits carry meaning. Many methods read or modify the existing string bytes directly; methods such as bit_slice, bitwise_not, bitwise_and, bitwise_or, bitwise_xor, bits, bit_offsets, bit_runs, and Array#mask allocate a derived result object. Because the API relies solely on String, the same methods would benefit memory-constrained implementations such as mruby and PicoRuby once adopted into CRuby.

A single keyword, lsb_first:, controls bit ordering across the API: it selects intra-byte numbering wherever positions are exchanged with the caller, and intra-byte scan direction wherever the API walks the sequence. Across-byte order is always byte[0] first, and result Strings from bit_slice are always packed LSB-first regardless, so data.each_bit_offset(true, lsb_first: false).all? { |n| data.bit_at(n, lsb_first: false) } stays true.

gem install string_bits

require "string_bits"
puts "\xAA\xAA\xAA\xAA".bit_at(10)
#=> false

puts "\xAA".each_bit(lsb_first: false).to_a.inspect
#=> [true, false, true, false, true, false, true, false]