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big: Add gcd_lcm fast path in wrapper.

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This commit is contained in:
Jeroen van Rijn
2021-08-11 20:59:52 +02:00
parent 6424a5a8dd
commit 320387c4ee
4 changed files with 40 additions and 31 deletions
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core/math/big/basic.odin
+35 -23
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@@ -1271,26 +1271,45 @@ _int_div_digit :: proc(quotient, numerator: ^Int, denominator: DIGIT) -> (remain
*/
int_gcd_lcm :: proc(res_gcd, res_lcm, a, b: ^Int) -> (err: Error) {
if err = clear_if_uninitialized(res_gcd, res_lcm, a, b); err != .None { return err; }
az, _ := is_zero(a); bz, _ := is_zero(b);
if az && bz {
if res_gcd != nil {
if err = zero(res_gcd); err != .None { return err; }
}
if res_lcm != nil {
if err = zero(res_lcm); err != .None { return err; }
}
return .None;
}
else if az {
if res_gcd != nil {
if err = abs(res_gcd, b); err != .None { return err; }
}
if res_lcm != nil {
if err = zero(res_lcm); err != .None { return err; }
}
return .None;
}
else if bz {
if res_gcd != nil {
if err = abs(res_gcd, a); err != .None { return err; }
}
if res_lcm != nil {
if err = zero(res_lcm); err != .None { return err; }
}
return .None;
}
return #force_inline _int_gcd_lcm(res_gcd, res_lcm, a, b);
}
gcd_lcm :: proc { int_gcd_lcm, };
/*
Greatest Common Divisor using the binary method.
Greatest Common Divisor.
*/
int_gcd :: proc(res, a, b: ^Int) -> (err: Error) {
if err = clear_if_uninitialized(res, a, b); err != .None { return err; }
/*
If both `a` and `b` are zero, return zero.
If either `a` or `b`, return the other one.
*/
az, _ := is_zero(a); bz, _ := is_zero(b);
if az && bz { return zero(res); }
else if az { return abs(res, b); }
else if bz { return abs(res, a); }
return #force_inline _int_gcd_lcm(res, nil, a, b);
return #force_inline int_gcd_lcm(res, nil, a, b);
}
gcd :: proc { int_gcd, };
@@ -1298,20 +1317,13 @@ gcd :: proc { int_gcd, };
Least Common Multiple.
*/
int_lcm :: proc(res, a, b: ^Int) -> (err: Error) {
if err = clear_if_uninitialized(res, a, b); err != .None { return err; }
/*
If both `a` and `b` are zero, return zero.
*/
az, _ := is_zero(a); bz, _ := is_zero(b);
if az || bz { return zero(res); }
return #force_inline _int_gcd_lcm(nil, res, a, b);
return #force_inline int_gcd_lcm(nil, res, a, b);
}
lcm :: proc { int_lcm, };
/*
Internal function computing both GCD and (if target isn't `nil`) also LCM.
Internal function computing both GCD using the binary method,
and, if target isn't `nil`, also LCM.
Expects the arguments to have been initialized.
*/
_int_gcd_lcm :: proc(res_gcd, res_lcm, a, b: ^Int) -> (err: Error) {