/* * include/linux/idr.h * * 2002-10-18 written by Jim Houston jim.houston@ccur.com * Copyright (C) 2002 by Concurrent Computer Corporation * Distributed under the GNU GPL license version 2. * * Small id to pointer translation service avoiding fixed sized * tables. */ #include <linux/types.h> #include <linux/bitops.h> #if BITS_PER_LONG == 32 # define IDR_BITS 5 # define IDR_FULL 0xfffffffful /* We can only use two of the bits in the top level because there is only one possible bit in the top level (5 bits * 7 levels = 35 bits, but you only use 31 bits in the id). */ # define TOP_LEVEL_FULL (IDR_FULL >> 30) #elif BITS_PER_LONG == 64 # define IDR_BITS 6 # define IDR_FULL 0xfffffffffffffffful /* We can only use two of the bits in the top level because there is only one possible bit in the top level (6 bits * 6 levels = 36 bits, but you only use 31 bits in the id). */ # define TOP_LEVEL_FULL (IDR_FULL >> 62) #else # error "BITS_PER_LONG is not 32 or 64" #endif #define IDR_SIZE (1 << IDR_BITS) #define IDR_MASK ((1 << IDR_BITS)-1) #define MAX_ID_SHIFT (sizeof(int)*8 - 1) #define MAX_ID_BIT (1U << MAX_ID_SHIFT) #define MAX_ID_MASK (MAX_ID_BIT - 1) /* Leave the possibility of an incomplete final layer */ #define MAX_LEVEL (MAX_ID_SHIFT + IDR_BITS - 1) / IDR_BITS /* Number of id_layer structs to leave in free list */ #define IDR_FREE_MAX MAX_LEVEL + MAX_LEVEL struct idr_layer { unsigned long bitmap; /* A zero bit means "space here" */ struct idr_layer *ary[1<<IDR_BITS]; int count; /* When zero, we can release it */ }; struct idr { struct idr_layer *top; struct idr_layer *id_free; int layers; int id_free_cnt; spinlock_t lock; }; #define IDR_INIT(name) \ { \ .top = NULL, \ .id_free = NULL, \ .layers = 0, \ .id_free_cnt = 0, \ .lock = SPIN_LOCK_UNLOCKED, \ } #define DEFINE_IDR(name) struct idr name = IDR_INIT(name) /* * This is what we export. */ void *idr_find(struct idr *idp, int id); int idr_pre_get(struct idr *idp, unsigned gfp_mask); int idr_get_new(struct idr *idp, void *ptr, int *id); int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id); void idr_remove(struct idr *idp, int id); void idr_init(struct idr *idp);