// SPDX-License-Identifier: MPL-2.0
// This is the implementation for the slab allocator for generic sizes
#ifndef SH_LIB_SLAB_GENERIC_H
#define SH_LIB_SLAB_GENERIC_H
#include "memory/page.h"
#include "std/status.h"
#include "std/type.h"
#include "memory/pba.h"
#define SH_SLAB_GENERIC_SLAB_DATA_PAGES {1,2,4,8,16,32,64,128}
#define SH_SLAB_GENERIC_OBJECT_SIZE_BYTES {8,16,32,64,128,256,512,1024}
#define SH_SLAB_GENERIC_OBJECTS_PER_SLAB 512
#define SH_SLAB_GENERIC_ACTUAL_OBJECTS_PER_SLAB {496,504,508,510,511,511,511,511}
#define SH_SLAB_GENERIC_SLAB_BITMAP_INIT {0xFFFF,0xFF,0xF,0x3,1,1,1,1}
#define SH_SLAB_GENERIC_SLAB_BITMAP_SIZE_BYTES 64
#define SH_SLAB_GENERIC_NULL_REF (sh_uint64)0
#define SH_SLAB_GENERIC_SLAB_SIG {'S','h','S','l','G','e','n','e'}
#define SH_SLAB_GENERIC_MAGIC 0x656E65476C536853ULL // little endian
// Generic slab structure
#pragma pack(1)
typedef struct sh_slab_generic_SLAB {
  sh_uint8 sig[8];
  sh_uint16 used_count;
  sh_uint64 slab_index;
  struct sh_slab_generic_SLAB* next_slab;
  struct sh_slab_generic_SLAB* prev_slab;
  struct sh_slab_generic_SLAB* next_partial;
  struct sh_slab_generic_SLAB* prev_partial;
  sh_uint8 padding[14];
  sh_uint64 free_bitmap[SH_SLAB_GENERIC_SLAB_BITMAP_SIZE_BYTES/8]; // First objects will be mark as unavailable due to being replaced by the header and bitmap, their amount depend on the object size
} sh_slab_generic_SLAB;
#pragma pack()
// Radix node slab allocator structure
struct sh_slab_generic_SLAB_ALLOCATOR {
  sh_slab_generic_SLAB* first_slab;
  sh_slab_generic_SLAB* partial_head;
  sh_uint64 level;
  sh_uint64 slab_count;
  sh_uint64 object_size_bytes;
  sh_uint64 object_per_slab;
  sh_uint64 actual_object_per_slab;
  sh_uint64 bitmap_init;
  sh_uint64 slab_pages_count;
  sh_pba_PAGE_BLOCK_ALLOCATOR* pba;
};
typedef sh_uint16 sh_slab_generic_OBJECT_INDEX_IN_SLAB;
// Initialize slab allocator structure. Does not allocate any slab
SH_STATUS sh_slab_generic_alloc_init(sh_uint8 level,struct sh_slab_generic_SLAB_ALLOCATOR* slab_alloc,sh_pba_PAGE_BLOCK_ALLOCATOR *pba);
// Allocate a new slab, initialize it and put it into the allocator. If new slab isn't the first to be allocated, push it on the partial slab list
SH_STATUS sh_slab_generic_add_slab(struct sh_slab_generic_SLAB_ALLOCATOR* alloc,sh_page_PAGE_TABLE_POOL *ptp,sh_slab_generic_SLAB** out_slab);
// Obtain a pointer to the first partial slab. Does not scan the slabs. Allocate a new slab if necessary
SH_STATUS sh_slab_generic_get_partial_slab(struct sh_slab_generic_SLAB_ALLOCATOR* alloc,sh_page_PAGE_TABLE_POOL* ptp,sh_slab_generic_SLAB** found_slab);
// Rescan all the slabs to rebuild partial list in case of doubt. Does not modify alloc->slab_count, any slab->free_bitmap or any slab>->nodes
SH_STATUS sh_slab_generic_scan_slabs(struct sh_slab_generic_SLAB_ALLOCATOR* alloc);
// Return a valid pointer to an empty object slot as well as the object index in the corresponding index. Slabs allocation is automated by sh_slab_generic_get_partial_slab
SH_STATUS sh_slab_generic_find_free_object(struct sh_slab_generic_SLAB_ALLOCATOR* alloc,sh_page_PAGE_TABLE_POOL *ptp,void** out,sh_slab_generic_OBJECT_INDEX_IN_SLAB* index_in_slab);
// Allocate one new object. Return a pointer to the struct of the new object. Since it call sh_slab_generic_find_free_object, it can allocate new slab
SH_STATUS sh_slab_generic_alloc(struct sh_slab_generic_SLAB_ALLOCATOR* alloc,sh_page_PAGE_TABLE_POOL *ptp,void** out_obj);
// Dellocate one radix node object provided as pointer.
SH_STATUS sh_slab_generic_dealloc(struct sh_slab_generic_SLAB_ALLOCATOR* alloc,void *object_ptr);
#endif