019f8fd211
git-subtree-dir: users/wpcarro git-subtree-mainline:464bbcb15cgit-subtree-split:24f5a642afChange-Id: I6105b3762b79126b3488359c95978cadb3efa789
113 lines
3.5 KiB
EmacsLisp
113 lines
3.5 KiB
EmacsLisp
;;; bytes.el --- Working with byte values -*- lexical-binding: t -*-
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;; Author: William Carroll <wpcarro@gmail.com>
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;; Version: 0.0.1
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;; URL: https://git.wpcarro.dev/wpcarro/briefcase
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;; Package-Requires: ((emacs "24.3"))
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;;; Commentary:
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;; Functions to help with human-readable representations of byte values.
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;;
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;; Usage:
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;; See the test cases for example usage. Or better yet, I should use a type of
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;; structured documentation that would allow me to expose a view into the test
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;; suite here. Is this currently possible in Elisp?
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;;
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;; API:
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;; - serialize :: Integer -> String
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;;
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;; Wish list:
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;; - Rounding: e.g. (bytes (* 1024 1.7)) => "2KB"
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;;; Code:
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;; TODO: Support -ibabyte variants like Gibibyte (GiB).
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;; Ranges:
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;; B: [ 0, 1e3)
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;; KB: [ 1e3, 1e6)
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;; MB: [ 1e6, 1e6)
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;; GB: [ 1e9, 1e12)
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;; TB: [1e12, 1e15)
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;; PB: [1e15, 1e18)
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;;
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;; Note: I'm currently not support exabytes because that causes the integer to
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;; overflow. I imagine a larger integer type may exist, but for now, I'll
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;; treat this as a YAGNI.
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(require 'prelude)
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(require 'tuple)
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(require 'math)
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(require 'number)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Constants
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(defconst bytes-kb (math-exp 2 10)
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"Number of bytes in a kilobyte.")
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(defconst bytes-mb (math-exp 2 20)
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"Number of bytes in a megabytes.")
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(defconst bytes-gb (math-exp 2 30)
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"Number of bytes in a gigabyte.")
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(defconst bytes-tb (math-exp 2 40)
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"Number of bytes in a terabyte.")
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(defconst bytes-pb (math-exp 2 50)
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"Number of bytes in a petabyte.")
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(defconst bytes-eb (math-exp 2 60)
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"Number of bytes in an exabyte.")
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Functions
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(defun bytes-classify (x)
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"Return unit that closest fits byte count, X."
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(prelude-assert (number-whole? x))
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(cond
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((and (>= x 0) (< x bytes-kb)) 'byte)
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((and (>= x bytes-kb) (< x bytes-mb)) 'kilobyte)
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((and (>= x bytes-mb) (< x bytes-gb)) 'megabyte)
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((and (>= x bytes-gb) (< x bytes-tb)) 'gigabyte)
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((and (>= x bytes-tb) (< x bytes-pb)) 'terabyte)
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((and (>= x bytes-pb) (< x bytes-eb)) 'petabyte)))
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(defun bytes-to-string (x)
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"Convert integer X into a human-readable string."
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(let ((base-and-unit
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(pcase (bytes-classify x)
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('byte (tuple/from 1 "B"))
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('kilobyte (tuple/from bytes-kb "KB"))
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('megabyte (tuple/from bytes-mb "MB"))
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('gigabyte (tuple/from bytes-gb "GB"))
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('terabyte (tuple/from bytes-tb "TB"))
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('petabyte (tuple/from bytes-pb "PB")))))
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(string-format "%d%s"
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(round x (tuple/first base-and-unit))
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(tuple/second base-and-unit))))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Tests
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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(progn
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(prelude-assert
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(equal "1000B" (bytes-to-string 1000)))
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(prelude-assert
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(equal "2KB" (bytes-to-string (* 2 bytes-kb))))
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(prelude-assert
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(equal "17MB" (bytes-to-string (* 17 bytes-mb))))
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(prelude-assert
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(equal "419GB" (bytes-to-string (* 419 bytes-gb))))
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(prelude-assert
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(equal "999TB" (bytes-to-string (* 999 bytes-tb))))
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(prelude-assert
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(equal "2PB" (bytes-to-string (* 2 bytes-pb)))))
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(provide 'bytes)
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;;; bytes.el ends here
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