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Merge bitcoin-core/secp256k1#1053: ecmult: move `_ecmult_odd_multiples_table_globalz_windowa` 

05e049b73c ecmult: move `_ecmult_odd_multiples_table_globalz_windowa` (siv2r)

Pull request description:

  Fixes #1035

  **Changes:**
      - move `secp256k1_ecmult_odd_multiples_table_globalz_windowa` function from ecmult to ecmult_const
      - remove outdated comment

ACKs for top commit:
  robot-dreams:
    utACK 05e049b73c (`diff` between removed and added lines is exactly as expected)
  real-or-random:
    utACK 05e049b73c

Tree-SHA512: 3fad4e93c641b642e84f4bbafcb8083d3e63b0523009fe0edcb2c1ebe1571d822320451289c651403ed1dc033ec6a7a3e8c3c56ad93d81bb1590cf9ff15a3b34
This commit is contained in:
Tim Ruffing 2021-12-25 00:10:56 +01:00
parent 09971a3ffd 05e049b73c
commit 9281c9f4e1
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GPG Key ID: 8C461CCD293F6011
2 changed files with 16 additions and 19 deletions
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16
src/ecmult_const_impl.h
View File

@ -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; \

19
src/ecmult_impl.h
View File

@ -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 { \