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Change num_mod semantics

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This commit is contained in:
Pieter Wuille 2013-04-21 00:58:15 +02:00
parent d06e61cbb5
commit 79b0ce6c84
3 changed files with 23 additions and 20 deletions
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2
src/impl/group.h
View file

@ -299,8 +299,6 @@ void static secp256k1_gej_split_exp(secp256k1_num_t *r1, secp256k1_num_t *r2, co
secp256k1_num_mul(&check, r2, &c->lambda);
secp256k1_num_add(&check, &check, r1);
secp256k1_num_mod(&check, &c->order);
secp256k1_num_add(&check, &check, &c->order);
secp256k1_num_mod(&check, &c->order);
secp256k1_num_mod(&a2, &c->order);
assert(secp256k1_num_cmp(&check, &a2) == 0);
secp256k1_num_free(&check);

38
src/impl/num_gmp.h
View file

@ -64,6 +64,22 @@ void static secp256k1_num_set_int(secp256k1_num_t *r, int a) {
r->data[0] = (a < 0) ? -a : a;
}
void static secp256k1_num_add_abs(secp256k1_num_t *r, const secp256k1_num_t *a, const secp256k1_num_t *b) {
mp_limb_t c = mpn_add(r->data, a->data, a->limbs, b->data, b->limbs);
r->limbs = a->limbs;
if (c != 0) {
assert(r->limbs < 2*NUM_LIMBS);
r->data[r->limbs++] = c;
}
}
void static secp256k1_num_sub_abs(secp256k1_num_t *r, const secp256k1_num_t *a, const secp256k1_num_t *b) {
mp_limb_t c = mpn_sub(r->data, a->data, a->limbs, b->data, b->limbs);
assert(c == 0);
r->limbs = a->limbs;
while (r->limbs > 1 && r->data[r->limbs-1]==0) r->limbs--;
}
void static secp256k1_num_mod(secp256k1_num_t *r, const secp256k1_num_t *m) {
secp256k1_num_sanity(r);
secp256k1_num_sanity(m);
@ -73,7 +89,11 @@ void static secp256k1_num_mod(secp256k1_num_t *r, const secp256k1_num_t *m) {
mpn_tdiv_qr(t, r->data, 0, r->data, r->limbs, m->data, m->limbs);
r->limbs = m->limbs;
while (r->limbs > 1 && r->data[r->limbs-1]==0) r->limbs--;
r->neg ^= m->neg;
}
if (r->neg && (r->limbs > 1 || r->data[0] != 0)) {
secp256k1_num_sub_abs(r, m, r);
r->neg = 0;
}
}
@ -142,22 +162,6 @@ int static secp256k1_num_cmp(const secp256k1_num_t *a, const secp256k1_num_t *b)
return mpn_cmp(a->data, b->data, a->limbs);
}
void static secp256k1_num_add_abs(secp256k1_num_t *r, const secp256k1_num_t *a, const secp256k1_num_t *b) {
mp_limb_t c = mpn_add(r->data, a->data, a->limbs, b->data, b->limbs);
r->limbs = a->limbs;
if (c != 0) {
assert(r->limbs < 2*NUM_LIMBS);
r->data[r->limbs++] = c;
}
}
void static secp256k1_num_sub_abs(secp256k1_num_t *r, const secp256k1_num_t *a, const secp256k1_num_t *b) {
mp_limb_t c = mpn_sub(r->data, a->data, a->limbs, b->data, b->limbs);
assert(c == 0);
r->limbs = a->limbs;
while (r->limbs > 1 && r->data[r->limbs-1]==0) r->limbs--;
}
void static secp256k1_num_subadd(secp256k1_num_t *r, const secp256k1_num_t *a, const secp256k1_num_t *b, int bneg) {
if (!(b->neg ^ bneg ^ a->neg)) { // a and b have the same sign
r->neg = a->neg;

3
src/num.h
View file

@ -51,7 +51,8 @@ void static secp256k1_num_mul(secp256k1_num_t *r, const secp256k1_num_t *a, cons
/** Divide two (signed) numbers. */
void static secp256k1_num_div(secp256k1_num_t *r, const secp256k1_num_t *a, const secp256k1_num_t *b);
/** Replace a number by its modulus. */
/** Replace a number by its remainder modulo m. M's sign is ignored. The result is a number between 0 and m-1,
even if r was negative. */
void static secp256k1_num_mod(secp256k1_num_t *r, const secp256k1_num_t *m);
/** Calculate the number of bits in (the absolute value of) a number. */