/**
* bitmap.h
* Copyright (c) 2022 Jon Santmyer <jon@jonsantmyer.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
* A freestanding implementation of a variable length bitmap.
* Depends on compiler provided header files
* stdint, stddef, stdbool
*
* Allocation for bitmap_vl is dependent on allocator implementation
* Static length bitmaps can be defined using this example
*
* struct bitmap_sl
* {
* struct bitmap_head head;
* bmcell_t cells[BITMAP_CELLS(n)];
* };
* where n is the number of bits you want in the bitmap
* To use said struct, you need to feed bmvl_setup with a cast pointer to
* bitmap_sl and the number of bits you have.
*
* For other bit systems, replace the type defined as
* bm_signed_t and bm_unsigned_t
* with an (u)int_t type of the proper bit length
*
* For using the bitmap, use the functions declared under #define blocks.
* The hidden functions are for genericising other bitmap types following
* the above format.
*
* bitmap_head contains a last_free variable which is used to accelerate the
* average allocation times. Instead of iterating through the entire map, the
* allocator can iterate from last_free until length.
* Most bm_take operations will be O(1) because last_free is assumed to mark an
* empty bit in the map
*/
#ifndef BITMAP_H
#define BITMAP_H 1
#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>
/*Can be changed to int32_t/uint32_t for 32-bit systems*/
typedef int64_t bm_signed_t;
typedef uint64_t bm_unsigned_t;
typedef bm_unsigned_t bmcell_t;
struct bitmap_head
{
size_t length;
size_t bits_free;
size_t last_free;
};
struct bitmap_vl
{
struct bitmap_head head;
bmcell_t cells[];
};
#define BITMAP_BITS_PER_CELL (8 * sizeof(bmcell_t))
#define BITMAP_CELLS(bits) \
((bits + (BITMAP_BITS_PER_CELL - 1)) / (BITMAP_BITS_PER_CELL))
#define BITMAP_LEN(bits) ((bits / 8) + (sizeof(struct bitmap_head)))
/*Fills a bitmap struct with proper length, and status vars. Zeros the cells*/
void bmvl_setup(struct bitmap_vl *bm, size_t bits);
/*Check if bit in bitmap is taken*/
bool __bm_test(bmcell_t *cells, size_t i);
#define bm_test(bitmap, i) __bm_test(bitmap->cells, i)
/*Functions for taking free bits in the bitmap. Returns -1 if none are
* available. Returns the index of the (first) bit if a suitable range is found
*/
bm_signed_t __bm_take(struct bitmap_head *head, bmcell_t *cells);
bm_signed_t __bm_take_contig(struct bitmap_head *head, bmcell_t *cells, size_t l);
#define bm_take(bitmap) __bm_take(&bitmap->head, bitmap->cells)
#define bm_take_contig(bitmap, l) \
__bm_take_contig(&bitmap->head, bitmap->cells, l)
/* Fills the bit/bits at i. Runs until l if applicable */
void __bm_reserve(struct bitmap_head *head, bmcell_t *cells, size_t i);
void __bm_reserve_contig(struct bitmap_head *head, bmcell_t *cells, size_t i, size_t l);
#define bm_reserve(bitmap, i) __bm_reserve(&bitmap->head, bitmap->cells, i)
#define bm_reserve_contig(bitmap, i, l) __bm_reserve_contig(&bitmap->head, bitmap->cells, i, l)
/* Clears the bit/bits at i. Runs until l if applicable */
void __bm_release(struct bitmap_head *head, bmcell_t *cells, size_t i);
void __bm_release_contig(struct bitmap_head *head, bmcell_t *cells, size_t i, size_t l);
#define bm_release(bitmap, i) __bm_release(&bitmap->head, bitmap->cells, i)
#define bm_release_contig(bitmap, i, l) __bm_release_contig(&bitmap->head, bitmap->cells, i, l)
#endif
