// Object manager. This file owns reference-counted kernel objects and handle-table lifetime rules.

#include <string.h>
#include <intrin.h>
#include <kernel/ob_object.h>
#include <kernel/mm_virt.h>

// Returns a diagnostic pool tag for the object type.
static uint32_t KiObjectPoolTag(OBJECT_TYPE type) {
    switch (type) {
    case ObjectTypeProcess:     return MM_POOL_TAG('p', 'r', 'o', 'c');
    case ObjectTypeThread:      return MM_POOL_TAG('t', 'h', 'r', 'd');
    case ObjectTypeMutex:       return MM_POOL_TAG('m', 't', 'x', ' ');
    case ObjectTypeSemaphore:   return MM_POOL_TAG('s', 'e', 'm', ' ');
    case ObjectTypeEvent:       return MM_POOL_TAG('e', 'v', 'n', 't');
    case ObjectTypeQueue:       return MM_POOL_TAG('q', 'u', 'e', 'u');
    case ObjectTypeFile:        return MM_POOL_TAG('f', 'i', 'l', 'e');
    case ObjectTypeDir:         return MM_POOL_TAG('d', 'i', 'r', ' ');
    case ObjectTypeAsyncIo:     return MM_POOL_TAG('a', 'i', 'o', ' ');
    case ObjectTypeSocket:      return MM_POOL_TAG('s', 'o', 'c', 'k');
    case ObjectTypeDevice:      return MM_POOL_TAG('d', 'e', 'v', ' ');
    case ObjectTypeDriver:      return MM_POOL_TAG('d', 'r', 'v', 'r');
    case ObjectTypeUsbDevice:   return MM_POOL_TAG('u', 's', 'b', 'd');
    case ObjectTypeUsbPipe:     return MM_POOL_TAG('u', 's', 'b', 'p');
    case ObjectTypeFileMapping: return MM_POOL_TAG('m', 'a', 'p', 'f');
    case ObjectTypeSurface:     return MM_POOL_TAG('s', 'u', 'r', 'f');
    case ObjectTypeInputQueue:  return MM_POOL_TAG('i', 'n', 'p', 'q');
    case ObjectTypeImageSection: return MM_POOL_TAG('i', 'm', 's', 'e');
    default:                    return MM_POOL_TAG('o', 'b', 'j', ' ');
    }
}

// Creates a zeroed, tagged object with one initial reference.
__declspec(dllexport) OBJECT* ObAllocateObject(OBJECT_TYPE type, size_t size) {
    if (size < sizeof(OBJECT)) size = sizeof(OBJECT);

    OBJECT* obj = (OBJECT *)MmAllocatePoolTag(size, KiObjectPoolTag(type));
    if (!obj) return (OBJECT *)0;

    memset(obj, 0, size);
    obj->Type     = type;
    obj->RefCount = 1;
    obj->Destroy  = (void *)0; // caller fills this in
    return obj;
}

// Implements the reference Object operation.
__declspec(dllexport) void ObReferenceObject(OBJECT* object) {
    if (!object) return;
    _InterlockedIncrement(&object->RefCount);
}

// Implements the dereference Object operation.
__declspec(dllexport) void ObDereferenceObject(OBJECT* object) {
    if (!object) return;
    long prev = _InterlockedDecrement(&object->RefCount);
    if (prev == 0) {
        // Reference count hit zero - run the destructor then free.
        if (object->Destroy) {
            object->Destroy(object);
        }
        MmFreePool(object);
    }
}