Fix some build problems with lambdas in MSVC

One of the problems is caused by a ternary operator having
different lambdas in the "if" and "else" clauses. This gives some
problem regarding type conversion. The ternary operator has been
replaced by an if/else construct.

The other problem regards a constexpr variable that is not captured. The
constexpr variable has been set to static constexpr.

This closes csete#197

lib/decode_rs_impl.cc

@@ -46,9 +46,11 @@ decode_rs_impl::decode_rs_impl(bool dual_basis, int interleave)
           "decode_rs", gr::io_signature::make(0, 0, 0), gr::io_signature::make(0, 0, 0)),
       d_interleave(interleave)
 {
-    d_decode_rs = dual_basis
-                      ? [](uint8_t* data) { return decode_rs_ccsds(data, NULL, 0, 0); }
-                      : [](uint8_t* data) { return decode_rs_8(data, NULL, 0, 0); };
+    if (dual_basis) {
+        d_decode_rs = [](uint8_t* data) { return decode_rs_ccsds(data, NULL, 0, 0); };
+    } else {
+        d_decode_rs = [](uint8_t* data) { return decode_rs_8(data, NULL, 0, 0); };
+    }
     d_rs_codeword.resize(d_ccsds_nn);
     d_nroots = d_ccsds_nroots;
 

lib/encode_rs_impl.cc

@@ -48,10 +48,14 @@ encode_rs_impl::encode_rs_impl(bool dual_basis, int interleave)
           "encode_rs", gr::io_signature::make(0, 0, 0), gr::io_signature::make(0, 0, 0)),
       d_interleave(interleave)
 {
-    constexpr int parity_offset = d_ccsds_nn - d_ccsds_nroots;
-    d_encode_rs =
-        dual_basis ? [](uint8_t* data) { encode_rs_ccsds(data, &data[parity_offset], 0); }
-                   : [](uint8_t* data) { encode_rs_8(data, &data[parity_offset], 0); };
+    static constexpr int parity_offset = d_ccsds_nn - d_ccsds_nroots;
+    if (dual_basis) {
+        d_encode_rs = [](uint8_t* data) {
+            encode_rs_ccsds(data, &data[parity_offset], 0);
+        };
+    } else {
+        d_encode_rs = [](uint8_t* data) { encode_rs_8(data, &data[parity_offset], 0); };
+    }
     d_rs_codeword.resize(d_ccsds_nn);
     d_nroots = d_ccsds_nroots;