From d5d7234e405be17f693b40feacc0de1319531a8d Mon Sep 17 00:00:00 2001
From: Holger Schemel <info@artsoft.org>
Date: Sun, 25 Apr 2021 00:06:44 +0200
Subject: [PATCH] added functions to convert between ISO-8859-1 and UTF-8

---
 src/libgame/misc.c | 118 +++++++++++++++++++++++++++++++++++++++++++++
 src/libgame/misc.h |   3 ++
 2 files changed, 121 insertions(+)

diff --git a/src/libgame/misc.c b/src/libgame/misc.c
index 7a3afc68..8dda88bc 100644
--- a/src/libgame/misc.c
+++ b/src/libgame/misc.c
@@ -1725,6 +1725,124 @@ void WriteUnusedBytesToFile(FILE *file, unsigned int bytes)
 }
 
 
+// ----------------------------------------------------------------------------
+// functions to convert between ISO-8859-1 and UTF-8
+// ----------------------------------------------------------------------------
+
+char *getUTF8FromLatin1(char *latin1)
+{
+  int max_utf8_size = 2 * strlen(latin1) + 1;
+  char *utf8 = checked_calloc(max_utf8_size);
+  unsigned char *src = (unsigned char *)latin1;
+  unsigned char *dst = (unsigned char *)utf8;
+
+  while (*src)
+  {
+    if (*src < 128)		// pure 7-bit ASCII
+    {
+      *dst++ = *src;
+    }
+    else if (*src >= 160)	// non-ASCII characters
+    {
+      *dst++ = 194 + (*src >= 192);
+      *dst++ = 128 + (*src & 63);
+    }
+    else			// undefined in ISO-8859-1
+    {
+      *dst++ = '?';
+    }
+
+    src++;
+  }
+
+  // only use the smallest possible string buffer size
+  utf8 = checked_realloc(utf8, strlen(utf8) + 1);
+
+  return utf8;
+}
+
+char *getLatin1FromUTF8(char *utf8)
+{
+  int max_latin1_size = strlen(utf8) + 1;
+  char *latin1 = checked_calloc(max_latin1_size);
+  unsigned char *src = (unsigned char *)utf8;
+  unsigned char *dst = (unsigned char *)latin1;
+
+  while (*src)
+  {
+    if (*src < 128)				// pure 7-bit ASCII
+    {
+      *dst++ = *src++;
+    }
+    else if (src[0] == 194 &&
+	     src[1] >= 128 && src[1] < 192)	// non-ASCII characters
+    {
+      *dst++ = src[1];
+      src += 2;
+    }
+    else if (src[0] == 195 &&
+	     src[1] >= 128 && src[1] < 192)	// non-ASCII characters
+    {
+      *dst++ = src[1] + 64;
+      src += 2;
+    }
+
+    // all other UTF-8 characters are undefined in ISO-8859-1
+
+    else if (src[0] >= 192 && src[0] < 224 &&
+	     src[1] >= 128 && src[1] < 192)
+    {
+      *dst++ = '?';
+      src += 2;
+    }
+    else if (src[0] >= 224 && src[0] < 240 &&
+	     src[1] >= 128 && src[1] < 192 &&
+	     src[2] >= 128 && src[2] < 192)
+    {
+      *dst++ = '?';
+      src += 3;
+    }
+    else if (src[0] >= 240 && src[0] < 248 &&
+	     src[1] >= 128 && src[1] < 192 &&
+	     src[2] >= 128 && src[2] < 192 &&
+	     src[3] >= 128 && src[3] < 192)
+    {
+      *dst++ = '?';
+      src += 4;
+    }
+    else if (src[0] >= 248 && src[0] < 252 &&
+	     src[1] >= 128 && src[1] < 192 &&
+	     src[2] >= 128 && src[2] < 192 &&
+	     src[3] >= 128 && src[3] < 192 &&
+	     src[4] >= 128 && src[4] < 192)
+    {
+      *dst++ = '?';
+      src += 5;
+    }
+    else if (src[0] >= 252 && src[0] < 254 &&
+	     src[1] >= 128 && src[1] < 192 &&
+	     src[2] >= 128 && src[2] < 192 &&
+	     src[3] >= 128 && src[3] < 192 &&
+	     src[4] >= 128 && src[4] < 192 &&
+	     src[5] >= 128 && src[5] < 192)
+    {
+      *dst++ = '?';
+      src += 6;
+    }
+    else
+    {
+      *dst++ = '?';
+      src++;
+    }
+  }
+
+  // only use the smallest possible string buffer size
+  latin1 = checked_realloc(latin1, strlen(latin1) + 1);
+
+  return latin1;
+}
+
+
 // ----------------------------------------------------------------------------
 // functions to translate key identifiers between different format
 // ----------------------------------------------------------------------------
diff --git a/src/libgame/misc.h b/src/libgame/misc.h
index 66b310e7..a8eaa335 100644
--- a/src/libgame/misc.h
+++ b/src/libgame/misc.h
@@ -225,6 +225,9 @@ void WriteUnusedBytesToFile(FILE *, unsigned int);
 #define putFileChunkBE(f,s,x) putFileChunk(f,s,x,BYTE_ORDER_BIG_ENDIAN)
 #define putFileChunkLE(f,s,x) putFileChunk(f,s,x,BYTE_ORDER_LITTLE_ENDIAN)
 
+char *getUTF8FromLatin1(char *);
+char *getLatin1FromUTF8(char *);
+
 char *getKeyNameFromKey(Key);
 char *getX11KeyNameFromKey(Key);
 Key getKeyFromKeyName(char *);
-- 
2.34.1