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-- check for overflow during numeric multiply
-- remove dead code (old common-factor finder) git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@9980 57a11ea4-9604-0410-9ed3-97b8803252fd
This commit is contained in:
Linas Vepstas
parent
28fa53b187
commit
0ff45c2de4
@ -49,7 +49,7 @@ typedef struct {
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} gncint128;
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static inline gncint128
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mult (gint64 a, gint64 b)
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mult128 (gint64 a, gint64 b)
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{
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gncint128 prod;
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short aneg=0, bneg=0;
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@ -113,7 +113,7 @@ mult (gint64 a, gint64 b)
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#ifdef TEST_128_BIT_MULT
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void pr (gint64 a, gint64 b)
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{
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gncint128 prod = mult (a,b);
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gncint128 prod = mult128 (a,b);
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printf ("%lld * %lld = %lld %llu (0x%llx %llx)\n", a,b, prod.hi, prod.lo, prod.hi, prod.lo);
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}
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@ -468,6 +468,7 @@ gnc_numeric_mul(gnc_numeric a, gnc_numeric b,
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gint64 denom, gint how)
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{
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gnc_numeric product, result;
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gncint128 bigprod;
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if(gnc_numeric_check(a) || gnc_numeric_check(b)) {
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return gnc_numeric_error(GNC_ERROR_ARG);
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@ -499,8 +500,15 @@ gnc_numeric_mul(gnc_numeric a, gnc_numeric b,
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b.denom = 1;
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}
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bigprod = mult128 (a.num, b.num);
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product.num = a.num*b.num;
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product.denom = a.denom*b.denom;
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if (0 != bigprod.hi)
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{
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/* We can try to do better, by reducing the fraction ... */
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return gnc_numeric_error (GNC_ERROR_OVERFLOW);
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}
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#if 0 /* currently, product denom won't ever be zero */
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if(product.denom < 0) {
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@ -880,15 +888,14 @@ gnc_numeric_lcd(gnc_numeric a, gnc_numeric b) {
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/********************************************************************
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* gnc_numeric_reduce
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* reduce a fraction by GCF elimination. This is NOT done as a
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** reduce a fraction by GCF elimination. This is NOT done as a
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* part of the arithmetic API unless GNC_DENOM_REDUCE is specified
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* as the output denominator.
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********************************************************************/
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#if 1
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gnc_numeric
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gnc_numeric_reduce(gnc_numeric in) {
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gnc_numeric_reduce(gnc_numeric in)
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{
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gint64 t;
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gint64 num = (in.num < 0) ? (- in.num) : in.num ;
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gint64 denom = in.denom;
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@ -898,97 +905,21 @@ gnc_numeric_reduce(gnc_numeric in) {
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return gnc_numeric_error(GNC_ERROR_ARG);
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}
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/* the strategy is to use euclid's algorithm */
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/* The strategy is to use Euclid's algorithm */
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while (denom > 0) {
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t = num % denom;
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num = denom;
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denom = t;
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}
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/* num = gcd */
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/* num now holds the GCD (Greatest Common Divisor) */
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/* all calculations are done on positive num, since it's not
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/* All calculations are done on positive num, since it's not
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* well defined what % does for negative values */
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out.num = in.num / num;
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out.denom = in.denom / num;
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return out;
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}
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#else
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gnc_numeric
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gnc_numeric_reduce(gnc_numeric in) {
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gint64 current_divisor = 2;
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gint64 max_square;
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gint64 num = (in.num < 0) ? (- in.num) : in.num ;
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gint64 denom = in.denom;
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int three_count = 0;
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gnc_numeric out;
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if(gnc_numeric_check(in)) {
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return gnc_numeric_error(GNC_ERROR_ARG);
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}
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/* the strategy is to eliminate common factors from
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* 2 up to 'max', where max is the smaller of the smaller
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* part of the fraction and the sqrt of the larger part of
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* the fraction. There's also the special case of the
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* smaller of fraction parts being a common factor.
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*
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* we test for 2 and 3 first, and thereafter skip all even numbers
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* and all odd multiples of 3 (that's every third odd number,
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* i.e. 9, 15, 21), thus the three_count stuff. */
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/* special case: one side divides evenly by the other */
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if (num == 0) {
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denom = 1;
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}
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else if((num > denom) && (num % denom == 0)) {
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num = num / denom;
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denom = 1;
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}
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else if ((num <= denom) && (denom % num == 0)) {
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denom = denom / num;
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num = 1;
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}
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max_square = (num > denom) ? denom : num;
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/* normal case: test 2, then 3, 5, 7, 11, etc.
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* (skip multiples of 2 and 3) */
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while(current_divisor * current_divisor <= max_square) {
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if((num % current_divisor == 0) &&
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(denom % current_divisor == 0)) {
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num = num / current_divisor;
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denom = denom / current_divisor;
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}
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else {
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if(current_divisor == 2) {
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current_divisor++;
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}
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else if(three_count == 3) {
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current_divisor += 4;
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three_count = 1;
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}
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else {
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current_divisor += 2;
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three_count++;
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}
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}
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if((current_divisor > num) ||
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(current_divisor > denom)) {
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break;
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}
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}
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/* all calculations are done on positive num, since it's not
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* well defined what % does for negative values */
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out.num = (in.num < 0) ? (- num) : num;
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out.denom = denom;
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return out;
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}
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#endif
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/********************************************************************
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* double_to_gnc_numeric
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********************************************************************/
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@ -1216,7 +1147,8 @@ gnc_numeric_div_with_error(gnc_numeric a, gnc_numeric b,
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********************************************************************/
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gchar *
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gnc_numeric_to_string(gnc_numeric n) {
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gnc_numeric_to_string(gnc_numeric n)
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{
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gchar *result;
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long long int tmpnum = n.num;
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long long int tmpdenom = n.denom;
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