1 files changed, 100 insertions, 0 deletions
diff --git a/libs/bsatk/src/filehash.cpp b/libs/bsatk/src/filehash.cpp
new file mode 100644
index 0000000..717a02c
--- /dev/null
+++ b/libs/bsatk/src/filehash.cpp
@@ -0,0 +1,100 @@
+/*
+Mod Organizer BSA handling
+
+Copyright (C) 2012 Sebastian Herbord. All rights reserved.
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Lesser General Public
+License as published by the Free Software Foundation; either
+version 3 of the License, or (at your option) any later version.
+
+This library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with this library; if not, write to the Free Software
+Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#include "filehash.h"
+
+#include <algorithm>
+#include <climits>
+#include <cstdlib>
+#include <cstring>
+
+#ifndef MAX_PATH
+#define MAX_PATH PATH_MAX
+#endif  // MAX_PATH
+
+static unsigned long genHashInt(const unsigned char* pos, const unsigned char* end)
+{
+  unsigned long hash = 0;
+  for (; pos < end; ++pos) {
+    hash *= 0x1003f;
+    hash += *pos;
+  }
+  return hash;
+}
+
+/**
+ * @brief calculateBSAHash
+ * @param fileName
+ * @return
+ * @note the hash calculated for folders seem to be wrong
+ */
+BSAHash calculateBSAHash(const std::string& fileName)
+{
+  char fileNameLower[FILENAME_MAX + 1];
+  int i = 0;
+  for (; i < FILENAME_MAX && fileName[i] != '\0'; ++i) {
+    fileNameLower[i] = tolower(fileName[i]);
+    if (fileNameLower[i] == '/') {
+      fileNameLower[i] = '\\';
+    }
+  }
+  fileNameLower[i] = '\0';
+
+  unsigned char* fileNameLowerU = reinterpret_cast<unsigned char*>(fileNameLower);
+
+  size_t length = strlen(fileNameLower);
+
+  char* ext = strrchr(fileNameLower, '.');
+  if (ext == nullptr) {
+    ext = fileNameLower + length;
+  }
+
+  size_t extLen = strlen(ext);
+  length -= extLen;
+
+  unsigned char* extU = reinterpret_cast<unsigned char*>(ext);
+
+  BSAHash hash1 = 0ULL;
+
+  if (length > 0) {
+    hash1 = static_cast<BSAHash>(fileNameLowerU[length - 1] |
+                                 ((length > 2 ? fileNameLowerU[length - 2] : 0) << 8) |
+                                 (length << 16) | (fileNameLowerU[0] << 24));
+  }
+
+  if (extLen > 0) {
+    if (strcmp(ext + 1, "kf") == 0) {
+      hash1 |= 0x80;
+    } else if (strcmp(ext + 1, "nif") == 0) {
+      hash1 |= 0x8000;
+    } else if (strcmp(ext + 1, "dds") == 0) {
+      hash1 |= 0x8080;
+    } else if (strcmp(ext + 1, "wav") == 0) {
+      hash1 |= 0x80000000;
+    }
+
+    BSAHash hash2 = static_cast<BSAHash>(genHashInt(fileNameLowerU + 1, extU - 2)) +
+                    static_cast<BSAHash>(genHashInt(extU, extU + strlen(ext)));
+
+    hash1 |= (hash2 & 0xFFFFFFFF) << 32;
+  }
+
+  return hash1;
+}