--- JSON-XS/XS.xs	2007/06/11 03:18:07	1.38
+++ JSON-XS/XS.xs	2007/06/11 03:42:57	1.39
@@ -499,6 +499,7 @@
     }
   else if (SvNOKp (sv))
     {
+      // trust that perl will do the right thing w.r.t. JSON syntax.
       need (enc, NV_DIG + 32);
       Gconvert (SvNVX (sv), NV_DIG, 0, enc->cur);
       enc->cur += strlen (enc->cur);
@@ -508,6 +509,7 @@
       // we assume we can always read an IV as a UV
       if (SvUV (sv) & ~(UV)0x7fff)
         {
+          // large integer, use the (rather slow) snprintf way.
           need (enc, sizeof (UV) * 3);
           enc->cur += 
              SvIsUV(sv)
@@ -520,6 +522,7 @@
           // code will likely be branchless and use only a single multiplication
           I32 i = SvIV (sv);
           U32 u;
+          char digit, nz = 0;
 
           need (enc, 6);
 
@@ -529,13 +532,16 @@
           // convert to 4.28 fixed-point representation
           u = u * ((0xfffffff + 10000) / 10000); // 10**5, 5 fractional digits
 
-          char digit, nz = 0;
-
+          // now output digit by digit, each time masking out the integer part
+          // and multiplying by 5 while moving the decimal point one to the right,
+          // resulting in a net multiplication by 10.
+          // we always write the digit to memory but conditionally increment
+          // the pointer, to ease the usage of conditional move instructions.
           digit = u >> 28; *enc->cur = digit + '0'; enc->cur += (nz = nz || digit); u = (u & 0xfffffff) * 5;
           digit = u >> 27; *enc->cur = digit + '0'; enc->cur += (nz = nz || digit); u = (u & 0x7ffffff) * 5;
           digit = u >> 26; *enc->cur = digit + '0'; enc->cur += (nz = nz || digit); u = (u & 0x3ffffff) * 5;
           digit = u >> 25; *enc->cur = digit + '0'; enc->cur += (nz = nz || digit); u = (u & 0x1ffffff) * 5;
-          digit = u >> 24; *enc->cur = digit + '0'; enc->cur += 1;
+          digit = u >> 24; *enc->cur = digit + '0'; enc->cur += 1; // correctly generate '0'
         }
     }
   else if (SvROK (sv))