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

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* 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.


git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@10080 57a11ea4-9604-0410-9ed3-97b8803252fd
This commit is contained in:
Derek Atkins 2004-06-25 16:15:40 +00:00
parent e65f9814e6
commit 753a7cff62
2 changed files with 24 additions and 8 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
2004-06-25 Derek Atkins <derek@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@ihtfp.com>
* Makefile.am: be sure to rebuild make-gnucash-patch and

26
src/engine/gnc-numeric.c
View File

@ -49,6 +49,7 @@ typedef struct {
guint64 hi;
guint64 lo;
short isneg;
short carry;
} gncint128;
/** Multiply a pair of signed 64-bit numbers,
@ -109,6 +110,7 @@ mult128 (gint64 a, gint64 b)
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 @@ div128 (gncint128 n, gint64 d)
quotient.hi += 1;
}
/* compute the carry situation */
quotient.carry = (quotient.hi || (quotient.lo >> 63));
return quotient;
}
@ -205,7 +210,7 @@ reduce128(gncint128 n, gint64 d)
/* 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 @@ reduce128(gncint128 n, gint64 d)
}
#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 @@ main ()
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 @@ main ()
prd (540,x,5);
prd (777,x,7);
prd (1111,x,11);
return 0;
}
#endif /* TEST_128_BIT_MULT */
@ -635,7 +645,7 @@ gnc_numeric_mul(gnc_numeric a, gnc_numeric b,
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))