1 files changed, 74 insertions, 0 deletions
diff --git a/src/base/io/MemoryStream.cpp b/src/base/io/MemoryStream.cpp
new file mode 100644
index 00000000..4c650f3e
--- /dev/null
+++ b/src/base/io/MemoryStream.cpp
@@ -0,0 +1,74 @@
+#include "cru/base/io/MemoryStream.h"
+
+#include <cstring>
+#include "cru/base/Exception.h"
+#include "cru/base/io/Stream.h"
+
+namespace cru::io {
+MemoryStream::MemoryStream(
+    std::byte* buffer, Index size, bool read_only,
+    std::function<void(std::byte* buffer, Index size)> release_func)
+    : Stream(true, true, !read_only),
+      buffer_(buffer),
+      size_(size),
+      position_(0),
+      release_func_(std::move(release_func)) {
+  if (!buffer) {
+    throw Exception(u"Buffer is nullptr");
+  }
+  if (size <= 0) {
+    throw Exception(u"Size is 0 or negative.");
+  }
+}
+
+MemoryStream::~MemoryStream() {}
+
+void MemoryStream::Close() { DoClose(); }
+
+Index MemoryStream::DoSeek(Index offset, SeekOrigin origin) {
+  switch (origin) {
+    case SeekOrigin::Current:
+      position_ += offset;
+      break;
+    case SeekOrigin::Begin:
+      position_ = offset;
+      break;
+    case SeekOrigin::End:
+      position_ = size_ + offset;
+      break;
+  }
+  return position_;
+}
+
+Index MemoryStream::DoRead(std::byte* buffer, Index offset, Index size) {
+  if (position_ + size > size_) {
+    size = size_ - position_;
+  }
+  if (size <= 0) {
+    return 0;
+  }
+  std::memmove(buffer + offset, buffer_ + position_, size);
+  position_ += size;
+  return size;
+}
+
+Index MemoryStream::DoWrite(const std::byte* buffer, Index offset, Index size) {
+  if (position_ + size > size_) {
+    size = size_ - position_;
+  }
+  if (size <= 0) {
+    return 0;
+  }
+  std::memmove(buffer_ + position_, buffer + offset, size);
+  position_ += size;
+  return size;
+}
+
+void MemoryStream::DoClose() {
+  CRU_STREAM_BEGIN_CLOSE
+  release_func_(buffer_, size_);
+  buffer_ = nullptr;
+  release_func_ = {};
+}
+
+}  // namespace cru::io