Add bin and edit workflow

bin/gems/ttfunk-1.8.0/lib/ttfunk/bin_utils.rb

@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+module TTFunk # rubocop: disable Style/Documentation # false positive
+  # Bit crunching utility methods.
+  module BinUtils
+    # Turn a bunch of small integers into one big integer. Assumes big-endian.
+    #
+    # @param arr [Array<Integer>]
+    # @param bit_width [Integer] bit width of the elements
+    # @return [Integer]
+    def stitch_int(arr, bit_width:)
+      value = 0
+
+      arr.each_with_index do |element, index|
+        value |= element << (bit_width * index)
+      end
+
+      value
+    end
+
+    # Slice a big integer into a bunch of small integers. Assumes big-endian.
+    #
+    # @param value [Integer]
+    # @param bit_width [Integer] bit width of the elements
+    # @param slice_count [Integer] number of elements to slice into. This is
+    #   needed for cases where top bits are zero.
+    # @return [Array<Integer>]
+    def slice_int(value, bit_width:, slice_count:)
+      mask = (2**bit_width) - 1
+
+      Array.new(slice_count) do |i|
+        (value >> (bit_width * i)) & mask
+      end
+    end
+
+    # Two's compliment to an integer.
+    #
+    # @param num [Integer]
+    # @param bit_width [Integer] number width
+    # @return [Integer]
+    def twos_comp_to_int(num, bit_width:)
+      if num >> (bit_width - 1) == 1
+        # we want all ones
+        mask = (2**bit_width) - 1
+
+        # find 2's complement, i.e. flip bits (xor with mask) and add 1
+        -((num ^ mask) + 1)
+      else
+        num
+      end
+    end
+
+    # Turns a (sorted) sequence of values into a series of two-element arrays
+    # where the first element is the start and the second is the length.
+    #
+    # @param values [Array<Integer>]
+    # @return [Array<Array(Integer, Integer)>]
+    def rangify(values)
+      values
+        .slice_when { |a, b| b - a > 1 }
+        .map { |span| [span.first, span.length - 1] }
+    end
+  end
+
+  BinUtils.extend(BinUtils)
+end