intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 40 insertions, 0 deletions

diff --git a/util/draft/memory.h b/util/draft/memory.h
new file mode 100644
index 0000000000..0a9722bb36
--- /dev/null
+++ b/util/draft/memory.h
@@ -0,0 +1,40 @@
+#pragma once
+
+#include <util/system/defaults.h>
+
+#include <algorithm>
+#include <functional>
+#include <utility>
+
+template <class T>
+inline bool IsZero(const T* begin, const T* end) {
+    return std::find_if(begin, end, [](const T& other) { return other != T(0); }) == end;
+}
+
+template <size_t Size>
+inline bool IsZero(const char* p) {
+    size_t sizeInUI64 = Size / 8;
+    const char* pEndUi64 = p + sizeInUI64 * 8;
+    if (sizeInUI64 && !IsZero<ui64>((const ui64*)p, (const ui64*)pEndUi64))
+        return false;
+    return IsZero(pEndUi64, p + Size);
+}
+
+#define IS_ZERO_INTSZ(INT)                           \
+    template <>                                      \
+    inline bool IsZero<sizeof(INT)>(const char* p) { \
+        return (*(INT*)p) == INT(0);                 \
+    }
+
+IS_ZERO_INTSZ(ui8)
+IS_ZERO_INTSZ(ui16)
+IS_ZERO_INTSZ(ui32)
+IS_ZERO_INTSZ(ui64)
+
+#undef IS_ZERO_INTSZ
+
+// If you want to use this to check all fields in a struct make sure it's w/o holes or #pragma pack(1)
+template <class T>
+bool IsZero(const T& t) {
+    return IsZero<sizeof(T)>((const char*)&t);
+}