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Abstract out verify logic for fe_normalize
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sipa committed May 11, 2023
1 parent 7fa5195 commit b6b6f9c
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Showing 4 changed files with 16 additions and 16 deletions.
7 changes: 5 additions & 2 deletions src/field.h
Original file line number Diff line number Diff line change
Expand Up @@ -75,10 +75,13 @@ static const secp256k1_fe secp256k1_const_beta = SECP256K1_FE_CONST(
/* In non-VERIFY mode, we #define the fe operations to be identical to their
* internal field implementation, to avoid the potential overhead of a
* function call (even though presumably inlinable). */
# define secp256k1_fe_normalize secp256k1_fe_impl_normalize
#endif /* !defined(VERIFY) */

/** Normalize a field element. This brings the field element to a canonical representation, reduces
* its magnitude to 1, and reduces it modulo field size `p`.
/** Normalize a field element.
*
* On input, r must be a valid field element.
* On output, r represents the same value but has normalized=1 and magnitude=1.
*/
static void secp256k1_fe_normalize(secp256k1_fe *r);

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8 changes: 1 addition & 7 deletions src/field_10x26_impl.h
Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,7 @@ static void secp256k1_fe_get_bounds(secp256k1_fe *r, int m) {
#endif
}

static void secp256k1_fe_normalize(secp256k1_fe *r) {
static void secp256k1_fe_impl_normalize(secp256k1_fe *r) {
uint32_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4],
t5 = r->n[5], t6 = r->n[6], t7 = r->n[7], t8 = r->n[8], t9 = r->n[9];

Expand Down Expand Up @@ -105,12 +105,6 @@ static void secp256k1_fe_normalize(secp256k1_fe *r) {

r->n[0] = t0; r->n[1] = t1; r->n[2] = t2; r->n[3] = t3; r->n[4] = t4;
r->n[5] = t5; r->n[6] = t6; r->n[7] = t7; r->n[8] = t8; r->n[9] = t9;

#ifdef VERIFY
r->magnitude = 1;
r->normalized = 1;
secp256k1_fe_verify(r);
#endif
}

static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
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8 changes: 1 addition & 7 deletions src/field_5x52_impl.h
Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@ static void secp256k1_fe_get_bounds(secp256k1_fe *r, int m) {
#endif
}

static void secp256k1_fe_normalize(secp256k1_fe *r) {
static void secp256k1_fe_impl_normalize(secp256k1_fe *r) {
uint64_t t0 = r->n[0], t1 = r->n[1], t2 = r->n[2], t3 = r->n[3], t4 = r->n[4];

/* Reduce t4 at the start so there will be at most a single carry from the first pass */
Expand Down Expand Up @@ -87,12 +87,6 @@ static void secp256k1_fe_normalize(secp256k1_fe *r) {
t4 &= 0x0FFFFFFFFFFFFULL;

r->n[0] = t0; r->n[1] = t1; r->n[2] = t2; r->n[3] = t3; r->n[4] = t4;

#ifdef VERIFY
r->magnitude = 1;
r->normalized = 1;
secp256k1_fe_verify(r);
#endif
}

static void secp256k1_fe_normalize_weak(secp256k1_fe *r) {
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9 changes: 9 additions & 0 deletions src/field_impl.h
Original file line number Diff line number Diff line change
Expand Up @@ -147,6 +147,15 @@ static void secp256k1_fe_verify(const secp256k1_fe *a) {
/* Invoke implementation-specific checks. */
secp256k1_fe_impl_verify(a);
}

static void secp256k1_fe_impl_normalize(secp256k1_fe *r);
SECP256K1_INLINE static void secp256k1_fe_normalize(secp256k1_fe *r) {
secp256k1_fe_verify(r);
secp256k1_fe_impl_normalize(r);
r->magnitude = 1;
r->normalized = 1;
secp256k1_fe_verify(r);
}
#endif /* defined(VERIFY) */

#endif /* SECP256K1_FIELD_IMPL_H */

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