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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/linux/idr.h | |
download | op-kernel-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip op-kernel-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'include/linux/idr.h')
-rw-r--r-- | include/linux/idr.h | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/include/linux/idr.h b/include/linux/idr.h new file mode 100644 index 0000000..ca3b7e4 --- /dev/null +++ b/include/linux/idr.h @@ -0,0 +1,78 @@ +/* + * 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); |