using tables for u8_analyze to speed it up

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@9734 d7cf8633-e32d-0410-b094-e92efae38249

diff --git a/utf8lib.c b/utf8lib.c
index a5fadae77221d878dfb0820767827a96b50322df..f7dff508feedb1d0b8e2d564be1000342e835e87 100644 (file)
--- a/utf8lib.c
+++ b/utf8lib.c
@@ -20,6 +20,36 @@ UTF-8 encoding and decoding functions follow.
 ================================================================================
 */
 
+unsigned char utf8_lengths[256] = { // 0 = invalid
+       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // ascii characters
+       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0x80 - 0xBF are within multibyte sequences
+       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // they could be interpreted as 2-byte starts but
+       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // the codepoint would be < 127
+       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+       0, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // C0 and C1 would also result in overlong encodings
+       2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+       3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+       4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+       // with F5 the codepoint is above 0x10FFFF,
+       // F8-FB would start 5-byte sequences
+       // FC-FD would start 6-byte sequences
+       // ...
+};
+Uchar utf8_range[5] = {
+       1,       // invalid - let's not allow the creation of 0-bytes :P
+       1,       // ascii minimum
+       0x80,    // 2-byte minimum
+       0x800,   // 3-byte minimum
+       0x10000, // 4-byte minimum
+};
+
 /** Analyze the next character and return various information if requested.
  * @param _s      An utf-8 string.
  * @param _start  Filled with the start byte-offset of the next valid character
@@ -32,21 +62,51 @@ UTF-8 encoding and decoding functions follow.
 static qboolean u8_analyze(const char *_s, size_t *_start, size_t *_len, Uchar *_ch, size_t _maxlen)
 {
        const unsigned char *s = (const unsigned char*)_s;
-       unsigned char bt, bc;
+       unsigned char bt;//, bc;
        size_t i;
        size_t bits, j;
        Uchar ch;
 
        i = 0;
 findchar:
+       while (i < _maxlen && s[i] && (bits = utf8_lengths[s[i]]) == 0)
+               ++i;
+
+       if (i >= _maxlen || !s[i]) {
+               if (_start) *_start = i;
+               if (_len) *_len = 0;
+               return false;
+       }
+       
+       if (bits == 1) { // ascii
+               if (_start) *_start = i;
+               if (_len) *_len = 1;
+               if (_ch) *_ch = (Uchar)s[i];
+               return true;
+       }
 
+       ch = (s[i] & (0xFF >> bits));
+       for (j = 1; j < bits; ++j)
+       {
+               if ( (s[i+j] & 0xC0) != 0x80 )
+               {
+                       i += j;
+                       goto findchar;
+               }
+               ch = (ch << 6) | (s[i+j] & 0x3F);
+       }
+       if (ch < utf8_range[bits] || ch >= 0x10FFFF)
+       {
+               i += bits;
+               goto findchar;
+       }
+#if 0
        // <0xC2 is always an overlong encoding, they're invalid, thus skipped
        while (i < _maxlen && s[i] && s[i] >= 0x80 && s[i] < 0xC2) {
                //fprintf(stderr, "skipping\n");
                ++i;
        }
 
-       //fprintf(stderr, "checking\n");
        // If we hit the end, well, we're out and invalid
        if(i >= _maxlen || !s[i]) {
                if (_start) *_start = i;
@@ -54,8 +114,8 @@ findchar:
                return false;
        }
 
-       //fprintf(stderr, "checking ascii\n");
-       // ascii characters
+       // I'll leave that in - if you remove it, also change the part below
+       // to support 1-byte chars correctly
        if (s[i] < 0x80)
        {
                if (_start) *_start = i;
@@ -64,7 +124,6 @@ findchar:
                //fprintf(stderr, "valid ascii\n");
                return true;
        }
-       //fprintf(stderr, "checking length\n");
 
        // Figure out the next char's length
        bc = s[i];
@@ -117,6 +176,7 @@ findchar:
                //fprintf(stderr, "overlong: %i bytes for %x\n", bits, ch);
                goto findchar;
        }
+#endif
 
        if (_start)
                *_start = i;