Load iw4x zones for iw4

src/ZoneLoading/Loading/Processor/ProcessorIW4xDecryption.cpp

@@ -0,0 +1,45 @@
+#include "ProcessorIW4xDecryption.h"
+
+#include <cassert>
+
+ProcessorIW4xDecryption::ProcessorIW4xDecryption()
+    : m_last_byte(0u)
+{
+}
+
+uint8_t ProcessorIW4xDecryption::RotateLeft(const uint8_t value, const unsigned count)
+{
+    assert(count < sizeof(value) * 8);
+    return static_cast<uint8_t>(value << count | (value >> ((sizeof(value) * 8) - count)));
+}
+
+uint8_t ProcessorIW4xDecryption::RotateRight(uint8_t value, const unsigned count)
+{
+    assert(count < sizeof(value) * 8);
+    return static_cast<uint8_t>(value >> count | (value << ((sizeof(value) * 8) - count)));
+}
+
+size_t ProcessorIW4xDecryption::Load(void* buffer, const size_t length)
+{
+    const auto readLen = m_base_stream->Load(buffer, length);
+
+    auto* charBuffer = static_cast<uint8_t*>(buffer);
+    for(auto i = 0u; i < readLen; i++)
+    {
+        auto value = charBuffer[i];
+        value ^= m_last_byte;
+        value = RotateLeft(value, 4);
+        value ^= -1;
+        value = RotateRight(value, 6);
+
+        charBuffer[i] = value;
+        m_last_byte = value;
+    }
+
+    return readLen;
+}
+
+int64_t ProcessorIW4xDecryption::Pos()
+{
+    return m_base_stream->Pos();
+}