fix bug 73710. rewrite the multi table conversion routine to support overlap range

for HKSCS and EUC-TW
rs=ftang

intl/uconv/src/nsUnicodeDecodeHelper.cpp

@@ -161,45 +161,65 @@ NS_IMETHODIMP nsUnicodeDecodeHelper::ConvertByMultiTable(
   nsresult res = NS_OK;
   PRInt32 i;
 
-  while ((srcLen > 0) && (dest < destEnd)) {
-    for (i=0; i<aTableCount; i++) 
-      if ((aRangeArray[i].min <= *src) && (*src <= aRangeArray[i].max)) break;
-
-    if (i == aTableCount) {
-      if (*src == (PRUint8)0xa0)
-        *dest = 0x00a0;
-      else
-        *dest = 0xfffd; 
-      bcr = 1;
-    }
-    else
+  while ((srcLen > 0) && (dest < destEnd)) 
+  {
+    PRBool done= PR_FALSE;
+    for (i=0; (!done) && (i<aTableCount); i++)  
     {
-        if (!uScan(aShiftTable[i], NULL, src, NS_REINTERPRET_CAST(PRUint16*, &med), srcLen, 
-        (PRUint32 *)&bcr)) {
-          res = NS_OK_UDEC_MOREINPUT;
-          break;
-        }
-        if (!uMapCode((uTable*) aMappingTable[i], NS_STATIC_CAST(PRUint16, med), NS_REINTERPRET_CAST(PRUint16*, dest))) {
-          if (med < 0x20) {
-            // somehow some table miss the 0x00 - 0x20 part
-            *dest = med;
-          } else {
-						// 2 for EUC-KR code set 1 and  EUC-JP codeset 1 and 2
-						// 3 for EUC-JP codeset 3, 4 for EUC-TW code set 3(CNS 11643 Plane 2 - 7)
-            if (bcr >= 2 && !(*(src+1) & 0x80) ) {
-                bcr-= (bcr-1);
+      if ((aRangeArray[i].min <= *src) && (*src <= aRangeArray[i].max)) 
+      {
+        if (uScan(aShiftTable[i], NULL, src, 
+                   NS_REINTERPRET_CAST(PRUint16*, &med), srcLen, 
+                   (PRUint32 *)&bcr)) 
+        {
+          done = uMapCode((uTable*) aMappingTable[i], 
+                          NS_STATIC_CAST(PRUint16, med), 
+                          NS_REINTERPRET_CAST(PRUint16*, dest)); 
+        } // if (uScan ... )
+      } // if Range
+    } // for loop
+
+    if(! done)
+    {
+      bcr = 1;
+      if (med < 0x20) {
+        // somehow some table miss the 0x00 - 0x20 part
+        *dest = med;
+      } else {
+        // we need to decide how many byte we skip. We can use uScan to do this
+        for (i=0; i<aTableCount; i++)  
+        {
+          if ((aRangeArray[i].min <= *src) && (*src <= aRangeArray[i].max)) 
+          {
+            if (uScan(aShiftTable[i], NULL, src, 
+                   NS_REINTERPRET_CAST(PRUint16*, &med), srcLen, 
+                   (PRUint32*)&bcr)) 
+            { 
+               // match the patten
+              
+               PRInt32 k; 
+               for(k = 1; k < bcr; k++)
+               {
+                 if(0 == (src[k]  & 0x80))
+                 { // only skip if all bytes > 0x80
+                   // if we hit bytes <= 0x80, skip only one byte
+                   bcr = 1;
+                   break; 
+                 }
+               }
+               break;
             }
-						// If stand-alone 0xa0 gets this far (BIG5), leave it alone.
-            // Otherwise, use Unicode replacement value for unmappable chars
-            *dest = (*src == (PRUint8)0xa0 ) ? 0x00a0 : 0xfffd;
           }
-       }
+        }
+        // treat it as NSBR if bcr == 1 and it is 0xa0
+        *dest = ((1==bcr)&&(*src == (PRUint8)0xa0 )) ? 0x00a0 : 0xfffd;
+      }
     }
 
     src += bcr;
     srcLen -= bcr;
     dest++;
-  }
+  } // while
 
   if ((srcLen > 0) && (res == NS_OK)) res = NS_OK_UDEC_MOREOUTPUT;