--- JSON-XS/XS.xs	2008/03/19 03:17:38	1.71
+++ JSON-XS/XS.xs	2008/03/19 04:08:22	1.72
@@ -62,6 +62,10 @@
 #define expect_false(expr) expect ((expr) != 0, 0)
 #define expect_true(expr)  expect ((expr) != 0, 1)
 
+#define IN_RANGE_INC(type,val,beg,end) \
+  ((unsigned type)((unsigned type)(val) - (unsigned type)(beg)) \
+  <= (unsigned type)((unsigned type)(end) - (unsigned type)(beg)))
+
 #ifdef USE_ITHREADS
 # define JSON_SLOW 1
 # define JSON_STASH (json_stash ? json_stash : gv_stashpv ("JSON::XS", 1))
@@ -104,18 +108,32 @@
 INLINE UV
 decode_utf8 (unsigned char *s, STRLEN len, STRLEN *clen)
 {
-  if (expect_false (s[0] > 0xdf || s[0] < 0xc2))
-    return utf8n_to_uvuni (s, len, clen, UTF8_CHECK_ONLY);
-  else if (len > 1 && s[1] >= 0x80 && s[1] <= 0xbf)
+  if (expect_true (len >= 2
+                   && IN_RANGE_INC (char, s[0], 0xc2, 0xdf)
+                   && IN_RANGE_INC (char, s[1], 0x80, 0xbf)))
     {
       *clen = 2;
       return ((s[0] & 0x1f) << 6) | (s[1] & 0x3f);
     }
   else
+    return utf8n_to_uvuni (s, len, clen, UTF8_CHECK_ONLY);
+}
+
+// likewise for encoding, also never called for ascii codepoints
+// this function takes advantage of this fact, although current gccs
+// seem to optimise the check for >= 0x80 away anyways
+INLINE unsigned char *
+encode_utf8 (unsigned char *s, UV ch)
+{
+  if (ch <= 0x7FF)
     {
-      *clen = (STRLEN)-1;
-      return (UV)-1;
+      *s++ = (ch >>   6) | 0xc0;
+      *s++ = (ch & 0x3f) | 0x80;
     }
+  else
+    s = uvuni_to_utf8_flags (s, ch, 0);
+
+  return s;
 }
 
 /////////////////////////////////////////////////////////////////////////////
@@ -209,7 +227,7 @@
                       clen = 1;
                     }
 
-                  if (uch < 0x20 || uch >= enc->limit)
+                  if (uch < 0x80/*0x20*/ || uch >= enc->limit)
                     {
                       if (uch > 0xFFFFUL)
                         {
@@ -253,7 +271,7 @@
                   else
                     {
                       need (enc, len += UTF8_MAXBYTES - 1); // never more than 11 bytes needed
-                      enc->cur = uvuni_to_utf8_flags (enc->cur, uch, 0);
+                      enc->cur = encode_utf8 (enc->cur, uch);
                       ++str;
                     }
                 }
@@ -861,7 +879,7 @@
                         {
                           utf8 = 1;
 
-                          cur = (char *)uvuni_to_utf8_flags (cur, hi, 0);
+                          cur = encode_utf8 (cur, hi);
                         }
                       else
                         *cur++ = hi;