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ecmult: move _ecmult_odd_multiples_table_globalz_windowa #1053

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Dec 24, 2021
+16 −19
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ecmult: move _ecmult_odd_multiples_table_globalz_windowa #1053

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16 changes: 16 additions & 0 deletions src/ecmult_const_impl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,22 @@
#include "ecmult_const.h"
#include "ecmult_impl.h"

/** Fill a table 'pre' with precomputed odd multiples of a.
*
* The resulting point set is brought to a single constant Z denominator, stores the X and Y
* coordinates as ge_storage points in pre, and stores the global Z in globalz.
* It only operates on tables sized for WINDOW_A wnaf multiples.
*/
static void secp256k1_ecmult_odd_multiples_table_globalz_windowa(secp256k1_ge *pre, secp256k1_fe *globalz, const secp256k1_gej *a) {
secp256k1_gej prej[ECMULT_TABLE_SIZE(WINDOW_A)];
secp256k1_fe zr[ECMULT_TABLE_SIZE(WINDOW_A)];

/* Compute the odd multiples in Jacobian form. */
secp256k1_ecmult_odd_multiples_table(ECMULT_TABLE_SIZE(WINDOW_A), prej, zr, a);
/* Bring them to the same Z denominator. */
secp256k1_ge_globalz_set_table_gej(ECMULT_TABLE_SIZE(WINDOW_A), pre, globalz, prej, zr);
}

/* This is like `ECMULT_TABLE_GET_GE` but is constant time */
#define ECMULT_CONST_TABLE_GET_GE(r,pre,n,w) do { \
int m = 0; \
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19 changes: 0 additions & 19 deletions src/ecmult_impl.h
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Expand Up @@ -96,25 +96,6 @@ static void secp256k1_ecmult_odd_multiples_table(int n, secp256k1_gej *prej, sec
secp256k1_fe_mul(&prej[n-1].z, &prej[n-1].z, &d.z);
}

/** Fill a table 'pre' with precomputed odd multiples of a.
*
* The resulting point set is brought to a single constant Z denominator, stores the X and Y
* coordinates as ge_storage points in pre, and stores the global Z in rz.
* It only operates on tables sized for WINDOW_A wnaf multiples.
*
* To compute a*P + b*G, we compute a table for P using this function,
* and use the precomputed table in <precomputed_ecmult.c> for G.
*/
static void secp256k1_ecmult_odd_multiples_table_globalz_windowa(secp256k1_ge *pre, secp256k1_fe *globalz, const secp256k1_gej *a) {
secp256k1_gej prej[ECMULT_TABLE_SIZE(WINDOW_A)];
secp256k1_fe zr[ECMULT_TABLE_SIZE(WINDOW_A)];

/* Compute the odd multiples in Jacobian form. */
secp256k1_ecmult_odd_multiples_table(ECMULT_TABLE_SIZE(WINDOW_A), prej, zr, a);
/* Bring them to the same Z denominator. */
secp256k1_ge_globalz_set_table_gej(ECMULT_TABLE_SIZE(WINDOW_A), pre, globalz, prej, zr);
}

/** The following two macro retrieves a particular odd multiple from a table
* of precomputed multiples. */
#define ECMULT_TABLE_GET_GE(r,pre,n,w) do { \
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