use eth* functions for c api

include/mcl/impl/bn_c_impl.hpp

@@ -137,23 +137,17 @@ int mclBn_setMapToMode(int mode)
 
 int mclBn_ethMsgToFp2(mclBnFp2 *out, const void *msg, size_t msgSize, uint8_t ctr, const void *dst, size_t dstSize)
 {
-	if (mclBn_getCurveType() != MCL_BLS12_381) return -1;
-	mcl::bn::BN::local::hashToFp2(*cast(out), msg, msgSize, ctr, dst, dstSize);
-	return 0;
+	return mcl::bn::ethMsgToFp2(*cast(out), msg, msgSize, ctr, dst, dstSize) ? 0 : -1;
 }
 
 int mclBn_ethFp2ToG2(mclBnG2 *out, const mclBnFp2 *t1, const mclBnFp2 *t2)
 {
-	if (mclBn_getCurveType() != MCL_BLS12_381) return -1;
-	mcl::bn::BN::param.mapTo.mapToG2_WB19_.opt_swu2_map(*cast(out), *cast(t1), cast(t2));
-	return 0;
+	return mcl::bn::ethFp2ToG2(*cast(out), *cast(t1), cast(t2)) ? 0 : -1;
 }
 
 int mclBn_ethMsgToG2(mclBnG2 *out, const void *msg, size_t msgSize, const void *dst, size_t dstSize)
 {
-	if (mclBn_getCurveType() != MCL_BLS12_381) return -1;
-	mcl::bn::BN::param.mapTo.mapToG2_WB19_.map2curve_osswu2(*cast(out), msg, msgSize, dst, dstSize);
-	return 0;
+	return mcl::bn::ethMsgToG2(*cast(out), msg, msgSize, dst, dstSize) ? 0 : -1;
 }
 
 void mclBn_setOriginalG2cofactor(int enable)