before sending the text to the sign, translate any unicode characters to codepage 437 representation

src/util.h

@@ -1,5 +1,9 @@
 #pragma once
 
+#include <map>
+#include <set>
+#include <unordered_map>
+
 // TODO: reverse engineer builtin and custom bitmaps
 
 // seems like our sign listens to messages on this address
@@ -246,6 +250,78 @@ enum class ExtendedChar {
     GreekSmallLetterPhi = 0xed,
 };
 
+std::unordered_map<uint16_t, uint8_t> createUnicodeToCP437Map() {
+    std::unordered_map<uint16_t, uint8_t> cp437_map;
+
+    cp437_map[0x00E4] = 0x84;  // ä in UTF-16
+    cp437_map[0xC3A4] = 0x84;  // ä in UTF-8
+    cp437_map[0x00F6] = 0x94;  // ö in UTF-16
+    cp437_map[0xC3B6] = 0x94;  // ö in UTF-8
+    cp437_map[0x00FC] = 0x81;  // ü in UTF-16
+    cp437_map[0xC3BC] = 0x81;  // ü in UTF-8
+    cp437_map[0x00C4] = 0x8E;  // Ä in UTF-16
+    cp437_map[0xC384] = 0x8E;  // Ä in UTF-8
+    cp437_map[0x00D6] = 0x99;  // Ö in UTF-16
+    cp437_map[0xC396] = 0x99;  // Ö in UTF-8
+    cp437_map[0x00DC] = 0x9A;  // Ü in UTF-16
+    cp437_map[0xC39C] = 0x9A;  // Ü in UTF-8
+    cp437_map[0x00DF] = 0xE1;  // ß in UTF-16
+    cp437_map[0xC39F] = 0xE1;  // ß in UTF-8
+    cp437_map[0x20AC] = 0xB1;  // € in UTF-16
+    cp437_map[0xE282AC] = 0xB1;  // € in UTF-8 (3 Bytes)
+    cp437_map[0x00B5] = 0xE6;  // µ in UTF-16
+    cp437_map[0xC2B5] = 0xE6;  // µ in UTF-8
+
+    return cp437_map;
+}
+
+String convertToCP437(const String& input) {
+    std::unordered_map<uint16_t, uint8_t> cp437_map = createUnicodeToCP437Map();
+    String output = "";
+    size_t len = input.length();
+
+    for (size_t i = 0; i < len; i++) {
+        char ch = input[i];
+
+        // UTF-8 detection: check for 3 byte UTF-8
+        if ((ch & 0xF0) == 0xE0) {
+            if (i + 2 < len) {
+                uint32_t utf8_char = ((uint8_t)input[i] << 16) | ((uint8_t)input[i + 1] << 8) | (uint8_t)input[i + 2];
+                i += 2;  // skip 2 additional bytes
+                if (cp437_map.find(utf8_char) != cp437_map.end()) {
+                    output += static_cast<char>(cp437_map[utf8_char]);
+                    continue;
+                }
+            }
+        }
+        // UTF-8 detection: check for 2 byte UTF-8
+        else if ((ch & 0xE0) == 0xC0) {
+            if (i + 1 < len) {
+                uint16_t utf8_char = ((uint8_t)input[i] << 8) | (uint8_t)input[i + 1];
+                i++;  // skip second byte
+                if (cp437_map.find(utf8_char) != cp437_map.end()) {
+                    output += static_cast<char>(cp437_map[utf8_char]);
+                    continue;
+                }
+            }
+        }
+        // single UTF-16 character (or plain ANSI character)
+        else if ((uint8_t)ch < 0x80) {  // keep ASCII as is
+            output += ch;
+        }
+        else {
+            uint16_t utf16_char = (uint8_t)ch;  // UTF-16 range
+            if (cp437_map.find(utf16_char) != cp437_map.end()) {
+                output += static_cast<char>(cp437_map[utf16_char]);
+            } else {
+                output += '?';
+            }
+        }
+    }
+
+    return output;
+}
+
 String hexDump(String in) {
     String out;
     for (size_t i = 0; i < in.length(); ++i) {
@@ -287,7 +363,6 @@ String hexDump(String in) {
  *   - stay time: 4
  *   - brightness: bright
  */
-
 void sendTextToSign(
     const String &text,
     const Method method = Method::Cyclic,
@@ -307,7 +382,9 @@ void sendTextToSign(
 
     Serial.println("Sending text: \"" + text + "\"");
 
-    String toSend = "~" + String(SIGN_ADDRESS, DEC) + "~f01" + (char) method + "\\" + (char) brightness + "\\Y" + String(speed, DEC) + "\\Z" + String(stayTime, DEC) + "\\" + (char) fontType + text + "\r\r\r";
+    String translatedText = convertToCP437(text);
+
+    String toSend = "~" + String(SIGN_ADDRESS, DEC) + "~f01" + (char) method + "\\" + (char) brightness + "\\Y" + String(speed, DEC) + "\\Z" + String(stayTime, DEC) + "\\" + (char) fontType + translatedText + "\r\r\r";
 
     Serial1.print(toSend);