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big: Add internal_int_montgomery_calc_normalization.

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This commit is contained in:
Jeroen van Rijn
2021-08-21 14:52:32 +02:00
parent 893cc013b5
commit 33df335ec9
2 changed files with 19 additions and 25 deletions
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core/math/big/prime.odin
+17 -24
View File
@@ -40,39 +40,32 @@ int_prime_is_divisible :: proc(a: ^Int, allocator := context.allocator) -> (res:
The method is slightly modified to shift B unconditionally upto just under
the leading bit of b. This saves alot of multiple precision shifting.
*/
/*
internal_int_montgomery_calc_normalization :: proc(a, b: ^Int) -> (err: Error) {
internal_int_montgomery_calc_normalization :: proc(a, b: ^Int, allocator := context.allocator) -> (err: Error) {
context.allocator = allocator;
/*
How many bits of last digit does b use.
*/
bits := internal_count_bits(b) % _DIGIT_BITS;
int x, bits;
mp_err err;
/* how many bits of last digit does b use */
bits = mp_count_bits(b) % MP_DIGIT_BIT;
if (b->used > 1) {
if ((err = mp_2expt(a, ((b->used - 1) * MP_DIGIT_BIT) + bits - 1)) != MP_OKAY) {
return err;
}
if b.used > 1 {
power := ((b.used - 1) * _DIGIT_BITS) + bits - 1;
internal_int_power_of_two(a, power) or_return;
} else {
mp_set(a, 1uL);
internal_one(a);
bits = 1;
}
/* now compute C = A * B mod b */
for (x = bits - 1; x < (int)MP_DIGIT_BIT; x++) {
if ((err = mp_mul_2(a, a)) != MP_OKAY) {
return err;
}
if (mp_cmp_mag(a, b) != MP_LT) {
if ((err = s_mp_sub(a, b, a)) != MP_OKAY) {
return err;
}
/*
Now compute C = A * B mod b.
*/
for x := bits - 1; x < _DIGIT_BITS; x += 1 {
internal_int_shl1(a, a) or_return;
if internal_cmp_mag(a, b) != -1 {
internal_sub(a, a, b) or_return;
}
}
return nil;
}
*/
/*
Sets up the Montgomery reduction stuff.
core/math/big/private.odin
+2 -1
View File
@@ -1548,7 +1548,8 @@ _private_int_log :: proc(a: ^Int, base: DIGIT, allocator := context.allocator) -
which uses the comba method to quickly calculate the columns of the reduction.
Based on Algorithm 14.32 on pp.601 of HAC.
*/
_private_montgomery_reduce_comba :: proc(x, n: ^Int, rho: DIGIT) -> (err: Error) {
_private_montgomery_reduce_comba :: proc(x, n: ^Int, rho: DIGIT, allocator := context.allocator) -> (err: Error) {
context.allocator = allocator;
W: [_WARRAY]_WORD = ---;
if x.used > _WARRAY { return .Invalid_Argument; }