From e1ca8022684238c0d67889d3eaf3076a16970299 Mon Sep 17 00:00:00 2001
From: Vinzenz Schroeter <vinzenz.f.s@gmail.com>
Date: Sun, 13 Oct 2024 13:42:20 +0200
Subject: [PATCH] CP437 conversion functions

---
 crates/servicepoint/src/cp437.rs | 77 ++++++++++++++++++++++++++------
 crates/servicepoint/src/lib.rs   |  2 +-
 2 files changed, 65 insertions(+), 14 deletions(-)

diff --git a/crates/servicepoint/src/cp437.rs b/crates/servicepoint/src/cp437.rs
index d82d180..a2250b3 100644
--- a/crates/servicepoint/src/cp437.rs
+++ b/crates/servicepoint/src/cp437.rs
@@ -46,7 +46,7 @@ impl Cp437Grid {
 
             for (index, char) in value.chars().enumerate() {
                 if !char.is_ascii() {
-                    return Err(InvalidChar { index, char });
+                    return Err(Cp437LoadError::InvalidChar { index, char });
                 }
 
                 let is_lf = char == '\n';
@@ -95,21 +95,15 @@ mod feature_cp437 {
 
     /// An array of 256 elements, mapping most of the CP437 values to UTF-8 characters
     ///
-    /// Mostly follows CP437, except for:
-    ///  * 0x0A & 0x0D are kept for use as line endings.
-    ///  * 0x1A is used for SAUCE.
-    ///  * 0x1B is used for ANSI escape sequences.
-    ///
-    /// These exclusions should be fine since most programs can't even use them
-    /// without issues. And this makes rendering simpler too.
+    /// Mostly follows CP437, except 0x0A, which is kept for use as line ending.
     ///
     /// See <https://en.wikipedia.org/wiki/Code_page_437#Character_set>
     ///
-    /// Copied from https://github.com/kip93/cp437-tools. License: GPL-3.0
+    /// Mostly copied from https://github.com/kip93/cp437-tools. License: GPL-3.0
     #[rustfmt::skip]
-    const CP437_TO_UTF8: [char; 256] = [
-        /* 0X */ '\0', '☺', '☻', '♥', '♦', '♣', '♠', '•', '◘', '○', '\n', '♂', '♀', '\r', '♫', '☼',
-        /* 1X */ '►', '◄', '↕', '‼', '¶', '§', '▬', '↨', '↑', '↓', '', '', '∟', '↔',  '▲', '▼',
+    pub const CP437_TO_UTF8: [char; 256] = [
+        /* 0X */ '\0', '☺', '☻', '♥', '♦', '♣', '♠', '•', '◘', '○', '\n', '♂', '♀', '♪', '♫', '☼',
+        /* 1X */ '►', '◄', '↕', '‼', '¶', '§', '▬', '↨', '↑', '↓', '→', '←', '∟', '↔',  '▲', '▼',
         /* 2X */ ' ', '!', '"', '#', '$', '%', '&', '\'','(', ')', '*', '+', ',', '-', '.', '/',
         /* 3X */ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ':', ';', '<', '=', '>', '?',
         /* 4X */ '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
@@ -187,6 +181,28 @@ mod feature_cp437 {
             grid
         }
     }
+
+    /// Convert the provided bytes to UTF-8.
+    pub fn cp437_to_str(cp437: &[u8]) -> String {
+        cp437.iter().map(move |char| cp437_to_char(*char)).collect()
+    }
+
+    /// Convert a single CP-437 character to UTF-8.
+    pub fn cp437_to_char(cp437: u8) -> char {
+        CP437_TO_UTF8[cp437 as usize]
+    }
+
+    /// Convert the provided text to CP-437 bytes.
+    ///
+    /// Characters that are not available are mapped to '?'.
+    pub fn str_to_cp437(utf8: &str) -> Vec<u8> {
+        utf8.chars().map(char_to_cp437).collect()
+    }
+
+    /// Convert a single UTF-8 character to CP-437.
+    pub fn char_to_cp437(utf8: char) -> u8 {
+        *UTF8_TO_CP437.get(&utf8).unwrap_or(&MISSING_CHAR_CP437)
+    }
 }
 
 #[cfg(test)]
@@ -219,7 +235,7 @@ mod tests {
 #[cfg(test)]
 #[cfg(feature = "cp437")]
 mod tests_feature_cp437 {
-    use crate::{CharGrid, Cp437Grid};
+    use super::*;
 
     #[test]
     fn round_trip_cp437() {
@@ -228,4 +244,39 @@ mod tests_feature_cp437 {
         let actual = CharGrid::from(&cp437);
         assert_eq!(actual, utf8);
     }
+
+    #[test]
+    fn convert_str() {
+        // test text from https://int10h.org/oldschool-pc-fonts/fontlist/font?ibm_bios
+        let utf8 = r#"A quick brown fox jumps over the lazy dog.
+        0123456789 ¿?¡!`'"., <>()[]{} &@%*^#$\/
+
+        * Wieniläinen sioux'ta puhuva ökyzombie diggaa Åsan roquefort-tacoja.
+        * Ça me fait peur de fêter noël là, sur cette île bizarroïde où une mère et sa môme essaient de me tuer avec un gâteau à la cigüe brûlé.
+        * Zwölf Boxkämpfer jagten Eva quer über den Sylter Deich.
+        * El pingüino Wenceslao hizo kilómetros bajo exhaustiva lluvia y frío, añoraba a su querido cachorro.
+
+        ┌─┬─┐ ╔═╦═╗ ╒═╤═╕ ╓─╥─╖
+        │ │ │ ║ ║ ║ │ │ │ ║ ║ ║
+        ├─┼─┤ ╠═╬═╣ ╞═╪═╡ ╟─╫─╢
+        └─┴─┘ ╚═╩═╝ ╘═╧═╛ ╙─╨─╜
+
+        ░░░░░ ▐▀█▀▌ .·∙•○°○•∙·.
+        ▒▒▒▒▒ ▐ █ ▌ ☺☻ ♥♦♣♠ ♪♫☼
+        ▓▓▓▓▓ ▐▀█▀▌  $ ¢ £ ¥ ₧
+        █████ ▐▄█▄▌ ◄►▲▼ ←→↑↓↕↨
+
+        ⌠
+        │dx ≡ Σ √x²ⁿ·δx
+        ⌡"#;
+
+        let cp437 = str_to_cp437(utf8);
+        let actual = cp437_to_str(&*cp437);
+        assert_eq!(utf8, actual)
+    }
+
+    #[test]
+    fn convert_invalid() {
+        assert_eq!(cp437_to_char(char_to_cp437('😜')), '?');
+    }
 }
diff --git a/crates/servicepoint/src/lib.rs b/crates/servicepoint/src/lib.rs
index fa5564e..d644bba 100644
--- a/crates/servicepoint/src/lib.rs
+++ b/crates/servicepoint/src/lib.rs
@@ -59,7 +59,7 @@ mod command_code;
 mod compression;
 mod compression_code;
 mod connection;
-mod cp437;
+pub mod cp437;
 mod data_ref;
 mod grid;
 mod origin;