README.md

bits

A smallish Clojure library for transforming Java primitives into binary sequences and back again. Intended to help explore encodings. Particularly useful for float and double types.

Installation

Leiningen:

[com.evanjbowling/bits "0.0.1"]

Demo

Start a REPL with this lib (WARN: only do this for dependencies you trust!):

clj -Sdeps '{:deps {com.evanjbowling/bits {:mvn/version "0.0.1"}}}'

Load the namespace:

(require '[com.evanjbowling.bits :as bits])

View the binary encoding for a few shorts:

(require '[clojure.pprint :as pp])
(require '[clojure.string :as str])

(defn print-shorts [shorts]
  (let [max-s (apply max (map (comp count str) shorts))]
    (doseq [s shorts]
      (let [padded-val (pp/cl-format nil (str "~" max-s "@a") s)
            ->str (fn[x](str/join "" x))]
        (printf "%s %s\n"
          padded-val
          (->str (bits/short-bits (short s))))))))

(print-shorts [Short/MIN_VALUE -1 0 1 Short/MAX_VALUE])
-32768 1000000000000000
    -1 1111111111111111
     0 0000000000000000
     1 0000000000000001
 32767 0111111111111111

Examine some chars:

(->> [\A \B \a \µ]
     (map bits/char-bits)
     clojure.pprint/pprint)

; ((0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 1)
;  (0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0)
;  (0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 1)
;  (0 0 0 0 0 0 0 0 1 0 1 1 0 1 0 1))

The floating point bit sequences are grouped [[sign] [exponent] [fraction]]:

(bits/float-bits (float 0.25)
; ([0] [0 1 1 1 1 1 0 1] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0])

(bits/from-float-bits '([0] [0 1 1 1 1 1 0 1] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]))
; 0.25

; make the exponent all ones for Infinity:
(bits/from-float-bits '([0] [1 1 1 1 1 1 1 1] [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]))
; Infinity

; then set a fraction bit to make a NaN:
(bits/from-float-bits '([0] [1 1 1 1 1 1 1 1] [1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]))
; NaN

License

Copyright © 2019-2024 Evan Bowling

Distributed under the MIT License