refactor: Decouple table generation and ecmult_gen context

bitcoin-core · Nov 19, 2021 · e43ba02 · e43ba02
1 parent 22dc2c0
commit e43ba02
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Showing 3 changed files with 9 additions and 14 deletions.
diff --git a/src/ecmult_gen_prec.h b/src/ecmult_gen_prec.h
@@ -9,8 +9,8 @@
 
 #include "ecmult_gen.h"
 
-static const size_t ECMULT_GEN_PREC_TABLE_SIZE = ROUND_TO_ALIGN(sizeof(*((secp256k1_ecmult_gen_context*) NULL)->prec));
+static const size_t ECMULT_GEN_PREC_TABLE_SIZE = ECMULT_GEN_PREC_N * ECMULT_GEN_PREC_G * sizeof(secp256k1_ge_storage);
 
-static void secp256k1_ecmult_gen_create_prec_table(secp256k1_ecmult_gen_context *ctx, void **prealloc);
+static void secp256k1_ecmult_gen_create_prec_table(secp256k1_ge_storage* table);
 
 #endif /* SECP256K1_ECMULT_GEN_PREC_H */
diff --git a/src/ecmult_gen_prec_impl.h b/src/ecmult_gen_prec_impl.h
@@ -12,14 +12,11 @@
 #include "field_impl.h"
 #include "ecmult_gen.h"
 
-static void secp256k1_ecmult_gen_create_prec_table(secp256k1_ecmult_gen_context *ctx, void **prealloc) {
+static void secp256k1_ecmult_gen_create_prec_table(secp256k1_ge_storage* table) {
     secp256k1_ge prec[ECMULT_GEN_PREC_N * ECMULT_GEN_PREC_G];
     secp256k1_gej gj;
     secp256k1_gej nums_gej;
     int i, j;
-    size_t const prealloc_size = ECMULT_GEN_PREC_TABLE_SIZE;
-    void* const base = *prealloc;
-    ctx->prec = (secp256k1_ge_storage (*)[ECMULT_GEN_PREC_N][ECMULT_GEN_PREC_G])manual_alloc(prealloc, prealloc_size, base, prealloc_size);
 
     /* get the generator */
     secp256k1_gej_set_ge(&gj, &secp256k1_ge_const_g);
@@ -70,7 +67,7 @@ static void secp256k1_ecmult_gen_create_prec_table(secp256k1_ecmult_gen_context
     }
     for (j = 0; j < ECMULT_GEN_PREC_N; j++) {
         for (i = 0; i < ECMULT_GEN_PREC_G; i++) {
-            secp256k1_ge_to_storage(&(*ctx->prec)[j][i], &prec[j*ECMULT_GEN_PREC_G + i]);
+            secp256k1_ge_to_storage(&table[j*ECMULT_GEN_PREC_G + i], &prec[j*ECMULT_GEN_PREC_G + i]);
         }
     }
 }

diff --git a/src/gen_context.c b/src/gen_context.c
@@ -35,8 +35,7 @@ static const secp256k1_callback default_error_callback = {
 };
 
 int main(int argc, char **argv) {
-    secp256k1_ecmult_gen_context ctx;
-    void *prealloc, *base;
+    secp256k1_ge_storage* table;
     int inner;
     int outer;
     FILE* fp;
@@ -59,13 +58,12 @@ int main(int argc, char **argv) {
     fprintf(fp, "#endif\n");
     fprintf(fp, "static const secp256k1_ge_storage secp256k1_ecmult_static_context[ECMULT_GEN_PREC_N][ECMULT_GEN_PREC_G] = {\n");
 
-    base = checked_malloc(&default_error_callback, ECMULT_GEN_PREC_TABLE_SIZE);
-    prealloc = base;
-    secp256k1_ecmult_gen_create_prec_table(&ctx, &prealloc);
+    table = checked_malloc(&default_error_callback, ECMULT_GEN_PREC_TABLE_SIZE);
+    secp256k1_ecmult_gen_create_prec_table(table);
     for(outer = 0; outer != ECMULT_GEN_PREC_N; outer++) {
         fprintf(fp,"{\n");
         for(inner = 0; inner != ECMULT_GEN_PREC_G; inner++) {
-            fprintf(fp,"    SC(%uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu)", SECP256K1_GE_STORAGE_CONST_GET((*ctx.prec)[outer][inner]));
+            fprintf(fp,"    SC(%uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu, %uu)", SECP256K1_GE_STORAGE_CONST_GET(table[outer * ECMULT_GEN_PREC_G + inner]));
             if (inner != ECMULT_GEN_PREC_G - 1) {
                 fprintf(fp,",\n");
             } else {
@@ -79,7 +77,7 @@ int main(int argc, char **argv) {
         }
     }
     fprintf(fp,"};\n");
-    free(base);
+    free(table);
 
     fprintf(fp, "#undef SC\n");
     fprintf(fp, "#endif\n");