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py: Fix bug in mpn_shl (multi-prec int shift left).

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Before this patch, eg, 1 << 75 (or any large multiple of 15) was setting
the MSB in the digits, which is outside the valid range of DIG_MASK.
This commit is contained in:
Damien George 2014-08-07 14:27:48 +00:00
parent 3ef911345c
commit 5d9b816449
1 changed files with 5 additions and 8 deletions
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13
py/mpz.c
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@ -89,12 +89,12 @@ STATIC uint mpn_shl(mpz_dig_t *idig, mpz_dig_t *jdig, uint jlen, uint n) {
mpz_dbl_dig_t d = 0;
for (uint i = jlen; i > 0; i--, idig--, jdig--) {
d |= *jdig;
*idig = d >> (DIG_SIZE - n_part);
*idig = (d >> (DIG_SIZE - n_part)) & DIG_MASK;
d <<= DIG_SIZE;
}
// store remaining bits
*idig = d >> (DIG_SIZE - n_part);
*idig = (d >> (DIG_SIZE - n_part)) & DIG_MASK;
idig -= n_whole - 1;
memset(idig, 0, (n_whole - 1) * sizeof(mpz_dig_t));
@ -1132,12 +1132,9 @@ mpz_t *mpz_gcd(const mpz_t *z1, const mpz_t *z2) {
lcm(0, 0) = 0
lcm(z, 0) = 0
*/
mpz_t *mpz_lcm(const mpz_t *z1, const mpz_t *z2)
{
// braces below are required for compilation to succeed with CL, see bug report
// https://connect.microsoft.com/VisualStudio/feedback/details/864169/compilation-error-when-braces-are-left-out-of-single-line-if-statement
if (z1->len == 0 || z2->len == 0) {
return mpz_zero();
mpz_t *mpz_lcm(const mpz_t *z1, const mpz_t *z2) {
if (z1->len == 0 || z2->len == 0) {
return mpz_zero();
}
mpz_t *gcd = mpz_gcd(z1, z2);