commit 5a1bb738f044777738bcdb32d10d7280a598b581
parent 009e7e6787cb153c0c5ffe1eea9a1991181873ba
Author: Eamon Caddigan <eamon.caddigan@gmail.com>
Date: Wed, 13 Dec 2023 20:28:25 -0800
R script to encode morse code
The approach is better described on the web than it is in the code:
<https://www.eamoncaddigan.net/december-adventure/2023-12/>
Diffstat:
| A | morseencode.R | | | 58 | ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 58 insertions(+), 0 deletions(-)
diff --git a/morseencode.R b/morseencode.R
@@ -0,0 +1,58 @@
+#!/usr/bin/env Rscript
+
+suppressPackageStartupMessages(library(dplyr))
+
+# Mapping from characters to morse code
+morse_dat <- tibble::tribble(
+ ~char, ~morse,
+ "0", "-----",
+ "1", ".----",
+ "2", "..---",
+ "3", "...--",
+ "4", "....-",
+ "5", ".....",
+ "6", "-....",
+ "7", "--...",
+ "8", "---..",
+ "9", "----.",
+ "A", ".-",
+ "B", "-...",
+ "C", "-.-.",
+ "D", "-..",
+ "E", ".",
+ "F", "..-.",
+ "G", "--.",
+ "H", "....",
+ "I", "..",
+ "J", ".---",
+ "K", "-.-",
+ "L", ".-..",
+ "M", "--",
+ "N", "-.",
+ "O", "---",
+ "P", ".--.",
+ "Q", "--.-",
+ "R", ".-.",
+ "S", "...",
+ "T", "-",
+ "U", "..-",
+ "V", "...-",
+ "W", ".--",
+ "X", "-..-",
+ "Y", "-.--",
+ "Z", "--.."
+)
+
+# Pack a Morse Code representation of a character into a short (16-bit)
+# integer. `.` becomes `01`, `-` becomes `11`, signals are encoded with the
+# early bits lower than later bits (they're "backwards".
+encode_morse <- function(morse_sequence) {
+ sum(((strsplit(morse_sequence, "")[[1]] == "-") * 2 + 1)
+ * 4^(seq(0, nchar(morse_sequence)-1)))
+}
+
+morse_dat <- morse_dat |>
+ mutate(morse_int = as.integer(vapply(morse, encode_morse, double(1))),
+ morse_hex = sprintf('%0.4x', morse_int))
+
+cat(morse_dat$morse_hex, sep = '\n')
