1 files changed, 98 insertions, 0 deletions
diff --git a/decoder/sparse_vector.cc b/decoder/sparse_vector.cc
new file mode 100644
index 00000000..4035b9ef
--- /dev/null
+++ b/decoder/sparse_vector.cc
@@ -0,0 +1,98 @@
+#include "sparse_vector.h"
+
+#include <iostream>
+#include <cstring>
+
+#include "hg_io.h"
+
+using namespace std;
+
+namespace B64 {
+
+void Encode(double objective, const SparseVector<double>& v, ostream* out) {
+  const int num_feats = v.num_active();
+  size_t tot_size = 0;
+  const size_t off_objective = tot_size;
+  tot_size += sizeof(double);                   // objective
+  const size_t off_num_feats = tot_size;
+  tot_size += sizeof(int);                      // num_feats
+  const size_t off_data = tot_size;
+  tot_size += sizeof(unsigned char) * num_feats; // lengths of feature names;
+  typedef SparseVector<double>::const_iterator const_iterator;
+  for (const_iterator it = v.begin(); it != v.end(); ++it)
+    tot_size += FD::Convert(it->first).size();   // feature names;
+  tot_size += sizeof(double) * num_feats;        // gradient
+  const size_t off_magic = tot_size;
+  tot_size += 4;                                 // magic
+
+  // size_t b64_size = tot_size * 4 / 3;
+  // cerr << "Sparse vector binary size: " << tot_size << "  (b64 size=" << b64_size << ")\n";
+  char* data = new char[tot_size];
+  *reinterpret_cast<double*>(&data[off_objective]) = objective;
+  *reinterpret_cast<int*>(&data[off_num_feats]) = num_feats;
+  char* cur = &data[off_data];
+  assert(cur - data == off_data);
+  for (const_iterator it = v.begin(); it != v.end(); ++it) {
+    const string& fname = FD::Convert(it->first);
+    *cur++ = static_cast<char>(fname.size());   // name len
+    memcpy(cur, &fname[0], fname.size());
+    cur += fname.size();
+    *reinterpret_cast<double*>(cur) = it->second;
+    cur += sizeof(double);
+  }
+  assert(cur - data == off_magic);
+  *reinterpret_cast<unsigned int*>(cur) = 0xBAABABBAu;
+  cur += sizeof(unsigned int);
+  assert(cur - data == tot_size);
+  b64encode(data, tot_size, out);
+  delete[] data;
+}
+
+bool Decode(double* objective, SparseVector<double>* v, const char* in, size_t size) {
+  v->clear();
+  if (size % 4 != 0) {
+    cerr << "B64 error - line % 4 != 0\n";
+    return false;
+  }
+  const size_t decoded_size = size * 3 / 4 - sizeof(unsigned int);
+  const size_t buf_size = decoded_size + sizeof(unsigned int);
+  if (decoded_size < 6) { cerr << "SparseVector decoding error: too short!\n"; return false; }
+  char* data = new char[buf_size];
+  if (!b64decode(reinterpret_cast<const unsigned char*>(in), size, data, buf_size)) {
+    delete[] data;
+    return false;
+  }
+  size_t cur = 0;
+  *objective = *reinterpret_cast<double*>(data);
+  cur += sizeof(double);
+  const int num_feats = *reinterpret_cast<int*>(&data[cur]);
+  cur += sizeof(int);
+  int fc = 0;
+  while(fc < num_feats && cur < decoded_size) {
+    ++fc;
+    const int fname_len = data[cur++];
+    assert(fname_len > 0);
+    assert(fname_len < 256);
+    string fname(fname_len, '\0');
+    memcpy(&fname[0], &data[cur], fname_len);
+    cur += fname_len;
+    const double val = *reinterpret_cast<double*>(&data[cur]);
+    cur += sizeof(double);
+    int fid = FD::Convert(fname);
+    v->set_value(fid, val);
+  }
+  if(num_feats != fc) {
+    cerr << "Expected " << num_feats << " but only decoded " << fc << "!\n";
+    delete[] data;
+    return false;
+  }
+  if (*reinterpret_cast<unsigned int*>(&data[cur]) != 0xBAABABBAu) {
+    cerr << "SparseVector decodeding error : magic does not match!\n";
+    delete[] data;
+    return false;
+  }
+  delete[] data;
+  return true;
+}
+
+}