75 lines
2.7 KiB
Markdown
75 lines
2.7 KiB
Markdown
# hamming
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Copyright (C) Jonathan Lamothe <jonathan@jlamothe.net>
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as
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published by the Free Software Foundation, either version 3 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public
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License along with this program. If not, see
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<https://www.gnu.org/licenses/>.
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## Executive Summary
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This is an educational tool designed for experimentation with Hamming
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codes. A hamming code consists of a certain number of data bits and a
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smaller number of check bits. The data bits are used to store
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information, and the check bits are used to verify the integrity of
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the message as a whole. In the event of a single bit error, the code
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provides enough information to restore the original message.
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For more information on hamming codes, see [this
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video](https://youtu.be/X8jsijhllIA) on YouTube.
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## Installation
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This program is written in [Haskell](https://haskell.org) using the
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Stack package manager. The easiest way to install it is by first
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installing [GHCup](https://www.haskell.org/ghcup/), and then from
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within the project directory, run the command: `stack install`
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You should then be able to run it by simply typing `hamming` on the
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command line. There are currently no command-line options.
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## Usage
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When run, the program will display a 16-bit extended hamming code in a
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4x4 grid. The rows and columns are numbered 0-3 and a green check
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mark or red X will be displayed in the upper left hand corner of the
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code indicating whether or not it's valid. The check bits will be
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highlighted to make them more easily identifiable.
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The program begins in display mode, but can be switched into edit mode
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to change the value of the individual bits. While in edit mode, the
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cursor will appear indicating the bit currently being edited.
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## Keyboard Commands
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In both modes of operation, these keys will have the following
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effects:
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- CTRL-C/Q: Quit the program.
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- C: Set the check bits to reflect the values in the data bits.
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- V: Correct to the nearest valid code (if possible).
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- R: Reset the code to all zeroes.
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### Display Mode
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- E: Enter edit mode.
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### Edit Mode
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- ESC: Return to display mode.
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- Up/K/CTRL-P: Move the cursor up.
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- Down/J/CTRL-N: Move the cursor down.
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- Left/H/CTRL-B: Move the cursor left.
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- Right/L/CTRL-F: Move the cursor right.
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- F: Flip the bit under the cursor (1 becomes 0; 0 becomes 1).
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