precompute_ecmult: Always compute all tables up to default WINDOW_G

Also simplify #ifdefs in generated file.
BlockstreamResearch · Dec 20, 2021 · 10461d8 · 10461d8
1 parent be6944a
commit 10461d8
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Showing 2 changed files with 32 additions and 30 deletions.
diff --git a/src/precompute_ecmult.c b/src/precompute_ecmult.c
@@ -32,7 +32,7 @@ static void print_table(FILE *fp, const char *name, int window_g, const secp256k
 
     j = 1;
     for(i = 3; i <= window_g; ++i) {
-        fprintf(fp, "#if ECMULT_TABLE_SIZE(WINDOW_G) > %ld\n", ECMULT_TABLE_SIZE(i-1));
+        fprintf(fp, "#if WINDOW_G > %d\n", i-1);
         for(;j < ECMULT_TABLE_SIZE(i); ++j) {
             fprintf(fp, ",S(%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32
                           ",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32")\n",
@@ -57,6 +57,8 @@ static void print_two_tables(FILE *fp, int window_g) {
 }
 
 int main(void) {
+    /* Always compute all tables for window sizes up to 15. */
+    int window_g = (ECMULT_WINDOW_SIZE < 15) ? 15 : ECMULT_WINDOW_SIZE;
     FILE* fp;
 
     fp = fopen("src/precomputed_ecmult.c","w");
@@ -77,15 +79,15 @@ int main(void) {
     fprintf(fp, "#include \"ecmult.h\"\n");
     fprintf(fp, "#include \"precomputed_ecmult.h\"\n");
     fprintf(fp, "#define S(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p) SECP256K1_GE_STORAGE_CONST(0x##a##u,0x##b##u,0x##c##u,0x##d##u,0x##e##u,0x##f##u,0x##g##u,0x##h##u,0x##i##u,0x##j##u,0x##k##u,0x##l##u,0x##m##u,0x##n##u,0x##o##u,0x##p##u)\n");
-    fprintf(fp, "#if ECMULT_TABLE_SIZE(ECMULT_WINDOW_SIZE) > %ld\n", ECMULT_TABLE_SIZE(ECMULT_WINDOW_SIZE));
+    fprintf(fp, "#if ECMULT_WINDOW_SIZE > %d\n", window_g);
     fprintf(fp, "   #error configuration mismatch, invalid ECMULT_WINDOW_SIZE. Try deleting precomputed_ecmult.c before the build.\n");
     fprintf(fp, "#endif\n");
     fprintf(fp, "#ifdef EXHAUSTIVE_TEST_ORDER\n");
     fprintf(fp, "#    error Cannot compile precomputed_ecmult.c in exhaustive test mode\n");
     fprintf(fp, "#endif /* EXHAUSTIVE_TEST_ORDER */\n");
     fprintf(fp, "#define WINDOW_G ECMULT_WINDOW_SIZE\n");
 
-    print_two_tables(fp, ECMULT_WINDOW_SIZE);
+    print_two_tables(fp, window_g);
 
     fprintf(fp, "#undef S\n");
     fclose(fp);