Merge pull request #4 from Richard-Qin-001/dev/shell

Rebuilt the system's underlying structure; it is now stable enough to merge. 

The system now supports a read-only file system and has a simple shell implemented.

1 files changed, 68 insertions, 0 deletions

diff --git a/src/kernel/cxx.cc b/src/kernel/cxx.cc
new file mode 100644
index 0000000..f9541b5
--- /dev/null
+++ b/src/kernel/cxx.cc
@@ -0,0 +1,68 @@
+#include "common/types.h"
+#include "kernel/pmm.h"
+#include "drivers/uart.h"
+
+/*
+ * C++ Kernel Runtime Support
+ *
+ * * Strategy: Map directly to PMM::alloc_page().
+ * Pros: Simple, works immediately for VFS.
+ * Cons: Allocates 4KB for every object (wasteful for small objects),
+ * but acceptable for current stage.
+ */
+
+void *operator new(unsigned long size)
+{
+    // Safety check: PMM allocates 4096 bytes max per call
+    if (size > 4096)
+    {
+        Drivers::uart_puts("panic: new allocation too big (max 4096)\n");
+        while (1)
+            ;
+    }
+
+    void *p = PMM::alloc_page();
+    if (!p)
+    {
+        Drivers::uart_puts("panic: new out of memory\n");
+        while (1)
+            ;
+    }
+    // PMM::alloc_page returns zeroed memory usually,
+    // but standard 'new' doesn't guarantee it.
+    // The constructor will handle initialization.
+    return p;
+}
+
+void *operator new[](unsigned long size)
+{
+    return operator new(size);
+}
+
+void operator delete(void *p)
+{
+    if (p)
+        PMM::free_page(p);
+}
+
+void operator delete[](void *p)
+{
+    if (p)
+        PMM::free_page(p);
+}
+
+// C++14 Sized Deallocation (Required by modern compilers)
+// The compiler optimizes 'delete' calls to pass the size of the object
+void operator delete(void *p, unsigned long size)
+{
+    (void)size; // We ignore size because PMM always frees a full page
+    if (p)
+        PMM::free_page(p);
+}
+
+void operator delete[](void *p, unsigned long size)
+{
+    (void)size;
+    if (p)
+        PMM::free_page(p);
+}
\ No newline at end of file