Fix libsnark dependency build.

This changes libsnark to build in-place, instead of copying first to
a build directory. Previously, modifications made to the original
sources wouldn't get rebuilt without a 'make clean' because users
would be pointing to the copies.

This closes #2689.

src/snark/libsnark/gadgetlib1/gadgets/hashes/hash_io.tcc

@@ -0,0 +1,105 @@
+/**
+ *****************************************************************************
+ * @author     This file is part of libsnark, developed by SCIPR Lab
+ *             and contributors (see AUTHORS).
+ * @copyright  MIT license (see LICENSE file)
+ *****************************************************************************/
+#ifndef HASH_IO_TCC_
+#define HASH_IO_TCC_
+
+namespace libsnark {
+
+template<typename FieldT>
+digest_variable<FieldT>::digest_variable(protoboard<FieldT> &pb,
+                                         const size_t digest_size,
+                                         const std::string &annotation_prefix) :
+    gadget<FieldT>(pb, annotation_prefix), digest_size(digest_size)
+{
+    bits.allocate(pb, digest_size, FMT(this->annotation_prefix, " bits"));
+}
+
+template<typename FieldT>
+digest_variable<FieldT>::digest_variable(protoboard<FieldT> &pb,
+                                         const size_t digest_size,
+                                         const pb_variable_array<FieldT> &partial_bits,
+                                         const pb_variable<FieldT> &padding,
+                                         const std::string &annotation_prefix) :
+    gadget<FieldT>(pb, annotation_prefix), digest_size(digest_size)
+{
+    assert(bits.size() <= digest_size);
+    bits = partial_bits;
+    while (bits.size() != digest_size)
+    {
+        bits.emplace_back(padding);
+    }
+}
+
+template<typename FieldT>
+void digest_variable<FieldT>::generate_r1cs_constraints()
+{
+    for (size_t i = 0; i < digest_size; ++i)
+    {
+        generate_boolean_r1cs_constraint<FieldT>(this->pb, bits[i], FMT(this->annotation_prefix, " bits_%zu", i));
+    }
+}
+
+template<typename FieldT>
+void digest_variable<FieldT>::generate_r1cs_witness(const bit_vector& contents)
+{
+    bits.fill_with_bits(this->pb, contents);
+}
+
+template<typename FieldT>
+bit_vector digest_variable<FieldT>::get_digest() const
+{
+    return bits.get_bits(this->pb);
+}
+
+template<typename FieldT>
+block_variable<FieldT>::block_variable(protoboard<FieldT> &pb,
+                                       const size_t block_size,
+                                       const std::string &annotation_prefix) :
+    gadget<FieldT>(pb, annotation_prefix), block_size(block_size)
+{
+    bits.allocate(pb, block_size, FMT(this->annotation_prefix, " bits"));
+}
+
+template<typename FieldT>
+block_variable<FieldT>::block_variable(protoboard<FieldT> &pb,
+                                       const std::vector<pb_variable_array<FieldT> > &parts,
+                                       const std::string &annotation_prefix) :
+    gadget<FieldT>(pb, annotation_prefix)
+{
+    for (auto &part : parts)
+    {
+        bits.insert(bits.end(), part.begin(), part.end());
+    }
+}
+
+template<typename FieldT>
+block_variable<FieldT>::block_variable(protoboard<FieldT> &pb,
+                                       const digest_variable<FieldT> &left,
+                                       const digest_variable<FieldT> &right,
+                                       const std::string &annotation_prefix) :
+    gadget<FieldT>(pb, annotation_prefix)
+{
+    assert(left.bits.size() == right.bits.size());
+    block_size = 2 * left.bits.size();
+    bits.insert(bits.end(), left.bits.begin(), left.bits.end());
+    bits.insert(bits.end(), right.bits.begin(), right.bits.end());
+}
+
+template<typename FieldT>
+void block_variable<FieldT>::generate_r1cs_witness(const bit_vector& contents)
+{
+    bits.fill_with_bits(this->pb, contents);
+}
+
+template<typename FieldT>
+bit_vector block_variable<FieldT>::get_block() const
+{
+    return bits.get_bits(this->pb);
+}
+
+} // libsnark
+#endif // HASH_IO_TCC_