Fix c++ build

Author: sipa

src/precompute_ecmult.c

@@ -75,6 +75,7 @@ int main(void) {
     fprintf(fp, "#include \"../include/secp256k1.h\"\n");
     fprintf(fp, "#include \"group.h\"\n");
     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, "   #error configuration mismatch, invalid ECMULT_WINDOW_SIZE. Try deleting precomputed_ecmult.c before the build.\n");

src/precompute_ecmult_gen.c

@@ -36,6 +36,7 @@ int main(int argc, char **argv) {
     fprintf(fp, "#include \"../include/secp256k1.h\"\n");
     fprintf(fp, "#include \"group.h\"\n");
     fprintf(fp, "#include \"ecmult_gen.h\"\n");
+    fprintf(fp, "#include \"precomputed_ecmult_gen.h\"\n");
     fprintf(fp, "#ifdef EXHAUSTIVE_TEST_ORDER\n");
     fprintf(fp, "#    error Cannot compile precomputed_ecmult_gen.c in exhaustive test mode\n");
     fprintf(fp, "#endif /* EXHAUSTIVE_TEST_ORDER */\n");

src/precomputed_ecmult.c

@@ -7,6 +7,10 @@
 #ifndef SECP256K1_PRECOMPUTED_ECMULT_H
 #define SECP256K1_PRECOMPUTED_ECMULT_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #include "group.h"
 #if defined(EXHAUSTIVE_TEST_ORDER)
 #if EXHAUSTIVE_TEST_ORDER == 13
@@ -24,4 +28,8 @@ extern const secp256k1_ge_storage secp256k1_pre_g[ECMULT_TABLE_SIZE(WINDOW_G)];
 extern const secp256k1_ge_storage secp256k1_pre_g_128[ECMULT_TABLE_SIZE(WINDOW_G)];
 #endif /* defined(EXHAUSTIVE_TEST_ORDER) */
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* SECP256K1_PRECOMPUTED_ECMULT_H */

src/precomputed_ecmult.h

@@ -7,6 +7,10 @@
 #ifndef SECP256K1_PRECOMPUTED_ECMULT_GEN_H
 #define SECP256K1_PRECOMPUTED_ECMULT_GEN_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #include "group.h"
 #include "ecmult_gen.h"
 #ifdef EXHAUSTIVE_TEST_ORDER
@@ -15,4 +19,8 @@ static secp256k1_ge_storage secp256k1_ecmult_gen_prec_table[ECMULT_GEN_PREC_N(EC
 extern 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)];
 #endif /* defined(EXHAUSTIVE_TEST_ORDER) */
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* SECP256K1_PRECOMPUTED_ECMULT_GEN_H */