Refactor UTF-16LE -> wchar conversion code

diff --git a/ext/mbstring/libmbfl/filters/mbfilter_utf16.c b/ext/mbstring/libmbfl/filters/mbfilter_utf16.c
index 620e8a76f7c5239c692e1425e09d6c879496073b..e4c9be9cbd7f782e53ec1539e315a36dccc2edc4 100644 (file)
--- a/ext/mbstring/libmbfl/filters/mbfilter_utf16.c
+++ b/ext/mbstring/libmbfl/filters/mbfilter_utf16.c
@@ -258,33 +258,42 @@ int mbfl_filt_conv_wchar_utf16be(int c, mbfl_convert_filter *filter)
  */
 int mbfl_filt_conv_utf16le_wchar(int c, mbfl_convert_filter *filter)
 {
-       int n;
-
        switch (filter->status) {
        case 0:
+               filter->cache = c & 0xff;
                filter->status = 1;
-               n = c & 0xff;
-               filter->cache |= n;
                break;
-       default:
-               filter->status = 0;
-               n = (filter->cache & 0xff) | ((c & 0xff) << 8);
-               if (n >= 0xd800 && n < 0xdc00) {
-                       filter->cache = ((n & 0x3ff) << 16) + 0x400000;
-               } else if (n >= 0xdc00 && n < 0xe000) {
-                       n &= 0x3ff;
-                       n |= (filter->cache & 0xfff0000) >> 6;
-                       filter->cache = 0;
-                       if (n >= MBFL_WCSPLANE_SUPMIN && n < MBFL_WCSPLANE_SUPMAX) {
-                               CK((*filter->output_function)(n, filter->data));
-                       } else {                /* illegal character */
-                               n &= MBFL_WCSGROUP_MASK;
-                               n |= MBFL_WCSGROUP_THROUGH;
-                               CK((*filter->output_function)(n, filter->data));
-                       }
+
+       case 1:
+               if ((c & 0xfc) == 0xd8) {
+                       /* Looks like we have a surrogate pair here */
+                       filter->cache += ((c & 0x3) << 8);
+                       filter->status = 2;
+               } else if ((c & 0xfc) == 0xdc) {
+                       /* This is wrong; the second part of the surrogate pair has come first
+                        * Flag it with `MBFL_WCSGROUP_THROUGH`; the following filter will handle
+                        * the error */
+                       int n = (filter->cache + ((c & 0xff) << 8)) | MBFL_WCSGROUP_THROUGH;
+                       filter->status = 0;
+                       CK((*filter->output_function)(n, filter->data));
                } else {
-                       filter->cache = 0;
+                       filter->status = 0;
+                       CK((*filter->output_function)(filter->cache + ((c & 0xff) << 8), filter->data));
+               }
+               break;
+
+       case 2:
+               filter->cache = (filter->cache << 10) + (c & 0xff);
+               filter->status = 3;
+               break;
+
+       case 3:
+               filter->status = 0;
+               int n = filter->cache + ((c & 0x3) << 8) + 0x10000;
+               if (n >= MBFL_WCSPLANE_SUPMIN && n < MBFL_WCSPLANE_SUPMAX) {
                        CK((*filter->output_function)(n, filter->data));
+               } else { /* illegal character */
+                       CK((*filter->output_function)((n & MBFL_WCSGROUP_MASK) | MBFL_WCSGROUP_THROUGH, filter->data));
                }
                break;
        }