--- JSON-XS/XS.xs	2008/03/19 13:44:43	1.73
+++ JSON-XS/XS.xs	2008/03/19 15:17:53	1.74
@@ -125,13 +125,20 @@
 INLINE unsigned char *
 encode_utf8 (unsigned char *s, UV ch)
 {
-  if (ch <= 0x7FF)
-    {
-      *s++ = (ch >>   6) | 0xc0;
-      *s++ = (ch & 0x3f) | 0x80;
-    }
-  else
-    s = uvuni_to_utf8_flags (s, ch, 0);
+  if      (expect_false (ch < 0x000080))
+    *s++ = ch;
+  else if (expect_true  (ch < 0x000800))
+    *s++ = 0xc0 | ( ch >>  6),
+    *s++ = 0x80 | ( ch        & 0x3f);
+  else if (              ch < 0x010000)
+    *s++ = 0xe0 | ( ch >> 12),
+    *s++ = 0x80 | ((ch >>  6) & 0x3f),
+    *s++ = 0x80 | ( ch        & 0x3f);
+  else if (              ch < 0x110000)
+    *s++ = 0xf0 | ( ch >> 18),
+    *s++ = 0x80 | ((ch >> 12) & 0x3f),
+    *s++ = 0x80 | ((ch >>  6) & 0x3f),
+    *s++ = 0x80 | ( ch        & 0x3f);
 
   return s;
 }
@@ -229,9 +236,9 @@
 
                   if (uch < 0x80/*0x20*/ || uch >= enc->limit)
                     {
-                      if (uch > 0xFFFFUL)
+                      if (uch >= 0x10000UL)
                         {
-                          if (uch > 0x10FFFFUL)
+                          if (uch >= 0x110000UL)
                             croak ("out of range codepoint (0x%lx) encountered, unrepresentable in JSON", (unsigned long)uch);
 
                           need (enc, len += 11);
@@ -640,11 +647,14 @@
     }
   else if (SvIOKp (sv))
     {
-      // we assume we can always read an IV as a UV
-      if (SvUV (sv) & ~(UV)0x7fff)
+      // we assume we can always read an IV as a UV and vice versa
+      // we assume two's complement
+      // we assume no aliasing issues in the union
+      if (SvIsUV (sv) ? SvUVX (sv) > 59000
+                      : SvIVX (sv) > 59000 || SvIVX (sv) < -59000)
         {
           // large integer, use the (rather slow) snprintf way.
-          need (enc, sizeof (UV) * 3);
+          need (enc, sizeof (UV) * 5 / 2 + 1); // CHAR_BIT is at least 8
           enc->cur += 
              SvIsUV(sv)
                 ? snprintf (enc->cur, sizeof (UV) * 3, "%"UVuf, (UV)SvUVX (sv))
@@ -654,7 +664,8 @@
         {
           // optimise the "small number case"
           // code will likely be branchless and use only a single multiplication
-          I32 i = SvIV (sv);
+          // works for numbers up to 59074
+          I32 i = SvIVX (sv);
           U32 u;
           char digit, nz = 0;
 
@@ -703,7 +714,7 @@
   enc.maxdepth  = DEC_DEPTH (enc.json.flags);
   enc.limit     = enc.json.flags & F_ASCII  ? 0x000080UL
                 : enc.json.flags & F_LATIN1 ? 0x000100UL
-                                            : 0x10FFFFUL;
+                                            : 0x110000UL;
 
   SvPOK_only (enc.sv);
   encode_sv (&enc, scalar);
@@ -891,7 +902,7 @@
                     ERR ("illegal backslash escape sequence in string");
                 }
             }
-          else if (expect_true (ch >= 0x20 && ch <= 0x7f))
+          else if (expect_true (ch >= 0x20 && ch < 0x80))
             *cur++ = ch;
           else if (ch >= 0x80)
             {