use new/delete on Windows

Author: adamant-pwn

cp-algo/util/new_big.hpp

@@ -1,20 +1,40 @@
 #ifndef CP_ALGO_UTIL_NEW_BIG_HPP
 #define CP_ALGO_UTIL_NEW_BIG_HPP
-#include <sys/mman.h>
+#include <cstddef>
+
+// Single macro to detect POSIX platforms (Linux, Unix, macOS)
+#if defined(__linux__) || defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
+#  define CP_ALGO_USE_MMAP 1
+#  include <sys/mman.h>
+#else
+#  define CP_ALGO_USE_MMAP 0
+#endif
+
 namespace cp_algo {
     template<typename T>
-    auto new_big(size_t len) {
-        auto raw = mmap(nullptr, len * sizeof(T),
-            PROT_READ | PROT_WRITE,
-            MAP_PRIVATE | MAP_ANONYMOUS,
-            -1, 0);
+    T* new_big(std::size_t len) {
+#if CP_ALGO_USE_MMAP
+        void* raw = mmap(nullptr, len * sizeof(T),
+                         PROT_READ | PROT_WRITE,
+                         MAP_PRIVATE | MAP_ANONYMOUS,
+                         -1, 0);
+        // Advise the kernel for huge pages and pre-populate writes
         madvise(raw, len * sizeof(T), MADV_HUGEPAGE);
         madvise(raw, len * sizeof(T), MADV_POPULATE_WRITE);
         return static_cast<T*>(raw);
+#else
+        // Fallback allocation for non-POSIX platforms
+        return new T[len];
+#endif
     }
     template<typename T>
-    void delete_big(T* ptr, size_t len) {
+    void delete_big(T* ptr, [[maybe_unused]] std::size_t len) {
+#if CP_ALGO_USE_MMAP
         munmap(ptr, len * sizeof(T));
+#else
+        // Match allocation with delete[] on non-POSIX platforms
+        delete[] ptr;
+#endif
     }
 }
 #endif // CP_ALGO_UTIL_NEW_BIG_HPP