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numeric_ext.c (int_powm): try bigint pow when overflow.

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This commit is contained in:
Yukihiro "Matz" Matsumoto
2022-08-26 12:37:54 +09:00
parent b4785044d5
commit 6598732892
1 changed files with 14 additions and 5 deletions
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mrbgems/mruby-numeric-ext/src/numeric_ext.c
+14 -5
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@@ -59,19 +59,19 @@ static mrb_value
int_powm(mrb_state *mrb, mrb_value x)
{
mrb_value m;
mrb_int base, exp, mod, result = 1;
mrb_int base, e, exp, mod, result = 1;
if (mrb_get_argc(mrb) == 1) {
return mrb_int_pow(mrb, x, mrb_get_arg1(mrb));
}
mrb_get_args(mrb, "io", &exp, &m);
if (exp < 0) mrb_raise(mrb, E_ARGUMENT_ERROR, "int.pow(n,m): n must be positive");
mrb_get_args(mrb, "io", &e, &m);
if (e < 0) mrb_raise(mrb, E_ARGUMENT_ERROR, "int.pow(n,m): n must be positive");
#ifdef MRB_USE_BIGINT
if (mrb_bigint_p(x)) {
return mrb_bint_powm(mrb, x, exp, m);
return mrb_bint_powm(mrb, x, e, m);
}
if (mrb_bigint_p(m)) {
return mrb_bint_powm(mrb, mrb_bint_new_int(mrb, mrb_integer(x)), exp, m);
return mrb_bint_powm(mrb, mrb_bint_new_int(mrb, mrb_integer(x)), e, m);
}
#endif
if (!mrb_integer_p(m)) mrb_raise(mrb, E_TYPE_ERROR, "int.pow(n,m): m must be integer");
@@ -80,17 +80,26 @@ int_powm(mrb_state *mrb, mrb_value x)
if (mod == 0) mrb_int_zerodiv(mrb);
if (mod == 1) return mrb_fixnum_value(0);
base = mrb_integer(x);
exp = e;
for (;;) {
if (exp & 1) {
if (mrb_int_mul_overflow(result, base, &result)) {
#ifdef MRB_USE_BIGINT
return mrb_bint_powm(mrb, mrb_bint_new_int(mrb, mrb_integer(x)), e, m);
#else
mrb_int_overflow(mrb, "pow");
#endif
}
result %= mod;
}
exp >>= 1;
if (exp == 0) break;
if (mrb_int_mul_overflow(base, base, &base)) {
#ifdef MRB_USE_BIGINT
return mrb_bint_powm(mrb, mrb_bint_new_int(mrb, mrb_integer(x)), e, m);
#else
mrb_int_overflow(mrb, "pow");
#endif
}
base %= mod;
}