[aandrejevic] 67827: [FAST486] Fix UnsignedDivMod128 (again). Fix Fast486FpuAdd to handle numbers whose difference of exponents is greater than the number of bits in the mantissa.

Author: aandrejevic
Date: Tue May 19 02:37:17 2015
New Revision: 67827

URL: http://svn.reactos.org/svn/reactos?rev=67827&view=rev
Log:
[FAST486]
Fix UnsignedDivMod128 (again).
Fix Fast486FpuAdd to handle numbers whose difference of exponents is greater than
the number of bits in the mantissa.


Modified:
    trunk/reactos/lib/fast486/fpu.c

Modified: trunk/reactos/lib/fast486/fpu.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/lib/fast486/fpu.c?rev=6782…
==============================================================================
--- trunk/reactos/lib/fast486/fpu.c	[iso-8859-1] (original)
+++ trunk/reactos/lib/fast486/fpu.c	[iso-8859-1] Tue May 19 02:37:17 2015
@@ -204,8 +204,15 @@
      * divisor has more than the original divisor
      */
     Bits = CountLeadingZeros64(Divisor);
-    if (CurrentHigh > 0ULL) Bits -= CountLeadingZeros64(CurrentHigh);
+    if (CurrentHigh > 0ULL) Bits += 64 - CountLeadingZeros64(CurrentHigh);
     else Bits -= CountLeadingZeros64(CurrentLow);
+
+    if (Bits >= 64)
+    {
+        *QuotientHigh = *QuotientLow;
+        *QuotientLow = 0ULL;
+        Bits -= 64;
+    }
 
     if (Bits)
     {
@@ -635,15 +642,33 @@
     /* Adjust the first operand to it... */
     if (FirstAdjusted.Exponent < TempResult.Exponent)
     {
-        FirstAdjusted.Mantissa >>= (TempResult.Exponent - FirstAdjusted.Exponent);
-        FirstAdjusted.Exponent = TempResult.Exponent;
+        if ((TempResult.Exponent - FirstAdjusted.Exponent) < 64)
+        {
+            FirstAdjusted.Mantissa >>= (TempResult.Exponent -
FirstAdjusted.Exponent);
+            FirstAdjusted.Exponent = TempResult.Exponent;
+        }
+        else
+        {
+            /* The second operand is the result */
+            *Result = *SecondOperand;
+            return TRUE;
+        }
     }
 
     /* ... and the second one too */
     if (SecondAdjusted.Exponent < TempResult.Exponent)
     {
-        SecondAdjusted.Mantissa >>= (TempResult.Exponent -
SecondAdjusted.Exponent);
-        SecondAdjusted.Exponent = TempResult.Exponent;
+        if ((TempResult.Exponent - FirstAdjusted.Exponent) < 64)
+        {
+            SecondAdjusted.Mantissa >>= (TempResult.Exponent -
SecondAdjusted.Exponent);
+            SecondAdjusted.Exponent = TempResult.Exponent;
+        }
+        else
+        {
+            /* The first operand is the result */
+            *Result = *FirstOperand;
+            return TRUE;
+        }
     }
 
     if (FirstAdjusted.Sign == SecondAdjusted.Sign)