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ecmult_gen: Precompute tables for all values of ECMULT_GEN_PREC_BITS

This commit is contained in:
Tim Ruffing 2021-11-08 19:28:47 +01:00
parent fdb33dd122
commit 5eba83f17c
1 changed files with 25 additions and 33 deletions
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30
src/gen_ecmult_gen_static_prec_table.c
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@ -4,12 +4,6 @@
* file COPYING or https://www.opensource.org/licenses/mit-license.php.*
***********************************************************************/
/* Autotools creates libsecp256k1-config.h, of which ECMULT_GEN_PREC_BITS is needed.
ifndef guard so downstream users can define their own if they do not use autotools. */
#if !defined(ECMULT_GEN_PREC_BITS)
#include "libsecp256k1-config.h"
#endif
/* In principle we could use ASM, but this yields only a minor speedup in
build time and it's very complicated. In particular when cross-compiling, we'd
need to build the ASM for the build and the host machine. */
@ -24,16 +18,9 @@
#include "ecmult_gen_prec_impl.h"
int main(int argc, char **argv) {
secp256k1_ge_storage* table;
int inner;
int outer;
const char outfile[] = "src/ecmult_gen_static_prec_table.h";
FILE* fp;
int bits = ECMULT_GEN_PREC_BITS;
int g = ECMULT_GEN_PREC_G(bits);
int n = ECMULT_GEN_PREC_N(bits);
table = checked_malloc(&default_error_callback, n * g * sizeof(secp256k1_ge_storage));
int bits;
(void)argc;
(void)argv;
@ -51,17 +38,20 @@ int main(int argc, char **argv) {
fprintf(fp, "#define SC SECP256K1_GE_STORAGE_CONST\n");
fprintf(fp, "#if ECMULT_GEN_PREC_BITS != %d\n", bits);
fprintf(fp, " #error configuration mismatch, invalid ECMULT_GEN_PREC_BITS. Try deleting ecmult_static_context.h before the build.\n");
fprintf(fp, "#endif\n");
fprintf(fp, "#ifdef EXHAUSTIVE_TEST_ORDER\n");
fprintf(fp, "static secp256k1_ge_storage secp256k1_ecmult_gen_prec_table[ECMULT_GEN_PREC_N(ECMULT_GEN_PREC_BITS)][ECMULT_GEN_PREC_G(ECMULT_GEN_PREC_BITS)];\n");
fprintf(fp, "#else\n");
fprintf(fp, "static const secp256k1_ge_storage secp256k1_ecmult_gen_prec_table[ECMULT_GEN_PREC_N(ECMULT_GEN_PREC_BITS)][ECMULT_GEN_PREC_G(ECMULT_GEN_PREC_BITS)] = {\n");
for (bits = 2; bits <= 8; bits *= 2) {
int g = ECMULT_GEN_PREC_G(bits);
int n = ECMULT_GEN_PREC_N(bits);
int inner, outer;
secp256k1_ge_storage* table = checked_malloc(&default_error_callback, n * g * sizeof(secp256k1_ge_storage));
secp256k1_ecmult_gen_create_prec_table(table, &secp256k1_ge_const_g, bits);
fprintf(fp, "#if ECMULT_GEN_PREC_BITS == %d\n", bits);
for(outer = 0; outer != n; outer++) {
fprintf(fp,"{\n");
for(inner = 0; inner != g; inner++) {
@ -78,9 +68,11 @@ int main(int argc, char **argv) {
fprintf(fp,"}\n");
}
}
fprintf(fp,"};\n");
fprintf(fp, "#endif\n");
free(table);
}
fprintf(fp, "};\n");
fprintf(fp, "#endif /* EXHAUSTIVE_TEST_ORDER */\n");
fprintf(fp, "#undef SC\n");
fprintf(fp, "#endif /* SECP256K1_ECMULT_GEN_STATIC_PREC_TABLE_H */\n");