[Gnucash-changes] Better "carry" flag to not overrun a signed 64-bit int (#114980).

[Derek Atkins]

Log Message:
-----------
Better "carry" flag to not overrun a signed 64-bit int (#114980).

	* src/engine/gnc-numeric.c: small change to the 128-bit math
	  routines to actually mark a 'carry bit' to denote numbers
	  >= 2^63 to fix bug #144980.

Modified Files:
--------------
    gnucash:
        ChangeLog
    gnucash/src/engine:
        gnc-numeric.c

Revision Data
-------------
Index: ChangeLog
===================================================================
RCS file: /home/cvs/cvsroot/gnucash/ChangeLog,v
retrieving revision 1.1818
retrieving revision 1.1819
diff -LChangeLog -LChangeLog -u -r1.1818 -r1.1819
--- ChangeLog
+++ ChangeLog
@@ -1,3 +1,9 @@
+2004-06-25  Derek Atkins  <derek at ihtfp.com>
+
+	* src/engine/gnc-numeric.c: small change to the 128-bit math
+	  routines to actually mark a 'carry bit' to denote numbers
+	  >= 2^63 to fix bug #144980.
+
 2004-06-24  Derek Atkins  <derek at ihtfp.com>
 
 	* Makefile.am: be sure to rebuild make-gnucash-patch and
Index: gnc-numeric.c
===================================================================
RCS file: /home/cvs/cvsroot/gnucash/src/engine/gnc-numeric.c,v
retrieving revision 1.34
retrieving revision 1.35
diff -Lsrc/engine/gnc-numeric.c -Lsrc/engine/gnc-numeric.c -u -r1.34 -r1.35
--- src/engine/gnc-numeric.c
+++ src/engine/gnc-numeric.c
@@ -49,6 +49,7 @@
   guint64 hi;
   guint64 lo;
   short isneg;
+  short carry;
 } gncint128;
 
 /** Multiply a pair of signed 64-bit numbers, 
@@ -109,6 +110,7 @@
 
   prod.lo = d0 + (sum<<32);
   prod.hi = carry + e1 + f1 + g0 + (g1<<32);
+  prod.carry = (prod.hi || (sum >> 31));
 
   return prod;
 }
@@ -162,6 +164,9 @@
     quotient.hi += 1;
   }
 
+  /* compute the carry situation */
+  quotient.carry = (quotient.hi || (quotient.lo >> 63));
+
   return quotient;
 }
 
@@ -205,7 +210,7 @@
   /* num now holds the GCD (Greatest Common Divisor) */
 
   gncint128 red = div128 (n, num);
-  if (red.hi)
+  if (red.carry)
   {
     return gnc_numeric_error (GNC_ERROR_OVERFLOW);
   }
@@ -216,22 +221,23 @@
 }
 
 #ifdef TEST_128_BIT_MULT
-void pr (gint64 a, gint64 b)
+static void pr (gint64 a, gint64 b)
 {
    gncint128 prod = mult128 (a,b);
-   printf ("%lld * %lld = %lld %llu (0x%llx %llx)\n", a,b, prod.hi, prod.lo, prod.hi, prod.lo);
+   printf ("%lld * %lld = %lld %llu (0x%llx %llx) %hd\n",
+	   a, b, prod.hi, prod.lo, prod.hi, prod.lo, prod.carry);
 }
 
-void prd (gint64 a, gint64 b, gint64 c)
+static void prd (gint64 a, gint64 b, gint64 c)
 {
    gncint128 prod = mult128 (a,b);
    gncint128 quot = div128 (prod, c);
    gint64 rem = rem128 (prod, c);
-   printf ("%lld * %lld / %lld = %lld %llu + %lld (0x%llx %llx)\n", a,b, c, quot.hi,
-quot.lo, rem, quot.hi, quot.lo);
+   printf ("%lld * %lld / %lld = %lld %llu + %lld (0x%llx %llx) %hd\n",
+	   a, b, c, quot.hi, quot.lo, rem, quot.hi, quot.lo, quot.carry);
 }
 
-main ()
+int main ()
 {
   pr (2,2);
 
@@ -252,6 +258,8 @@
   pr (x,x);
   pr (x,-x);
 
+  pr (1000000, 10000000000000);
+
   prd (x,x,2);
   prd (x,x,3);
   prd (x,x,4);
@@ -266,6 +274,8 @@
   prd (540,x,5);
   prd (777,x,7);
   prd (1111,x,11);
+
+  return 0;
 }
 
 #endif /* TEST_128_BIT_MULT */
@@ -635,7 +645,7 @@
   product.denom = a.denom*b.denom;
 
   /* If it looks to be overflowing, try to reduce the fraction ... */
-  if (0 != bigprod.hi)
+  if (bigprod.carry)
   {
     product = reduce128 (bigprod, product.denom);
     if (gnc_numeric_check (product))