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big: Add submod, mulmod, sqrmod.

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This commit is contained in:
Jeroen van Rijn
2021-07-26 15:07:58 +02:00
parent 5f7aeb3045
commit 9646d1f2b8
2 changed files with 37 additions and 5 deletions
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38
core/math/big/basic.odin
View File

@@ -656,7 +656,7 @@ sqr :: proc(dest, src: ^Int) -> (err: Error) {
divmod.
Both the quotient and remainder are optional and may be passed a nil.
*/
int_div :: proc(quotient, remainder, numerator, denominator: ^Int) -> (err: Error) {
int_divmod :: proc(quotient, remainder, numerator, denominator: ^Int) -> (err: Error) {
/*
Early out if neither of the results is wanted.
*/
@@ -692,7 +692,12 @@ int_div :: proc(quotient, remainder, numerator, denominator: ^Int) -> (err: Erro
return err;
}
div :: proc{ int_div, };
divmod :: proc{ int_divmod, };
int_div :: proc(quotient, numerator, denominator: ^Int) -> (err: Error) {
return int_divmod(quotient, nil, numerator, denominator);
}
div :: proc { int_div, };
/*
remainder = numerator % denominator.
@@ -700,7 +705,7 @@ div :: proc{ int_div, };
denominator < remainder <= 0 if denominator < 0
*/
int_mod :: proc(remainder, numerator, denominator: ^Int) -> (err: Error) {
if err = div(nil, remainder, numerator, denominator); err != .None { return err; }
if err = divmod(nil, remainder, numerator, denominator); err != .None { return err; }
z: bool;
if z, err = is_zero(remainder); z || denominator.sign == remainder.sign { return .None; }
@@ -717,6 +722,33 @@ int_addmod :: proc(remainder, number, addend, modulus: ^Int) -> (err: Error) {
}
addmod :: proc { int_addmod, };
/*
remainder = (number - decrease) % modulus.
*/
int_submod :: proc(remainder, number, decrease, modulus: ^Int) -> (err: Error) {
if err = add(remainder, number, decrease); err != .None { return err; }
return mod(remainder, remainder, modulus);
}
submod :: proc { int_submod, };
/*
remainder = (number * multiplicand) % modulus.
*/
int_mulmod :: proc(remainder, number, multiplicand, modulus: ^Int) -> (err: Error) {
if err = mul(remainder, number, multiplicand); err != .None { return err; }
return mod(remainder, remainder, modulus);
}
mulmod :: proc { int_mulmod, };
/*
remainder = (number * number) % modulus.
*/
int_sqrmod :: proc(remainder, number, modulus: ^Int) -> (err: Error) {
if err = sqr(remainder, number); err != .None { return err; }
return mod(remainder, remainder, modulus);
}
sqrmod :: proc { int_sqrmod, };
/*
==========================
Low-level routines

4
core/math/big/example.odin
View File

@@ -69,10 +69,10 @@ demo :: proc() {
err = set (numerator, 3);
err = set (denominator, 2);
err = set (quotient, 3);
err = set (quotient, 5);
err = zero(remainder);
err = addmod(remainder, numerator, denominator, quotient);
err = mulmod(remainder, numerator, denominator, quotient);
if err != .None {
fmt.printf("Error: %v\n", err);
} else {