diff options
Diffstat (limited to 'src/alloc.h')
| -rw-r--r-- | src/alloc.h | 383 |
1 files changed, 383 insertions, 0 deletions
diff --git a/src/alloc.h b/src/alloc.h new file mode 100644 index 0000000..095134a --- /dev/null +++ b/src/alloc.h @@ -0,0 +1,383 @@ +// Copyright © Tavian Barnes <tavianator@tavianator.com> +// SPDX-License-Identifier: 0BSD + +/** + * Memory allocation. + */ + +#ifndef BFS_ALLOC_H +#define BFS_ALLOC_H + +#include "prelude.h" +#include <errno.h> +#include <stddef.h> +#include <stdlib.h> + +/** Check if a size is properly aligned. */ +static inline bool is_aligned(size_t align, size_t size) { + return (size & (align - 1)) == 0; +} + +/** Round down to a multiple of an alignment. */ +static inline size_t align_floor(size_t align, size_t size) { + return size & ~(align - 1); +} + +/** Round up to a multiple of an alignment. */ +static inline size_t align_ceil(size_t align, size_t size) { + return align_floor(align, size + align - 1); +} + +/** + * Saturating array size. + * + * @param align + * Array element alignment. + * @param size + * Array element size. + * @param count + * Array element count. + * @return + * size * count, saturating to the maximum aligned value on overflow. + */ +static inline size_t array_size(size_t align, size_t size, size_t count) { + size_t ret = size * count; + return ret / size == count ? ret : ~(align - 1); +} + +/** Saturating array sizeof. */ +#define sizeof_array(type, count) \ + array_size(alignof(type), sizeof(type), count) + +/** Size of a struct/union field. */ +#define sizeof_member(type, member) \ + sizeof(((type *)NULL)->member) + +/** + * Saturating flexible struct size. + * + * @param align + * Struct alignment. + * @param min + * Minimum struct size. + * @param offset + * Flexible array member offset. + * @param size + * Flexible array element size. + * @param count + * Flexible array element count. + * @return + * The size of the struct with count flexible array elements. Saturates + * to the maximum aligned value on overflow. + */ +static inline size_t flex_size(size_t align, size_t min, size_t offset, size_t size, size_t count) { + size_t ret = size * count; + size_t overflow = ret / size != count; + + size_t extra = offset + align - 1; + ret += extra; + overflow |= ret < extra; + ret |= -overflow; + ret = align_floor(align, ret); + + // Make sure flex_sizeof(type, member, 0) >= sizeof(type), even if the + // type has more padding than necessary for alignment + if (min > align_ceil(align, offset)) { + ret = ret < min ? min : ret; + } + + return ret; +} + +/** + * Computes the size of a flexible struct. + * + * @param type + * The type of the struct containing the flexible array. + * @param member + * The name of the flexible array member. + * @param count + * The length of the flexible array. + * @return + * The size of the struct with count flexible array elements. Saturates + * to the maximum aligned value on overflow. + */ +#define sizeof_flex(type, member, count) \ + flex_size(alignof(type), sizeof(type), offsetof(type, member), sizeof_member(type, member[0]), count) + +/** + * General memory allocator. + * + * @param align + * The required alignment. + * @param size + * The size of the allocation. + * @return + * The allocated memory, or NULL on failure. + */ +attr(malloc(free, 1), aligned_alloc(1, 2)) +void *alloc(size_t align, size_t size); + +/** + * Zero-initialized memory allocator. + * + * @param align + * The required alignment. + * @param size + * The size of the allocation. + * @return + * The allocated memory, or NULL on failure. + */ +attr(malloc(free, 1), aligned_alloc(1, 2)) +void *zalloc(size_t align, size_t size); + +/** Allocate memory for the given type. */ +#define ALLOC(type) \ + (type *)alloc(alignof(type), sizeof(type)) + +/** Allocate zeroed memory for the given type. */ +#define ZALLOC(type) \ + (type *)zalloc(alignof(type), sizeof(type)) + +/** Allocate memory for an array. */ +#define ALLOC_ARRAY(type, count) \ + (type *)alloc(alignof(type), sizeof_array(type, count)) + +/** Allocate zeroed memory for an array. */ +#define ZALLOC_ARRAY(type, count) \ + (type *)zalloc(alignof(type), sizeof_array(type, count)) + +/** Allocate memory for a flexible struct. */ +#define ALLOC_FLEX(type, member, count) \ + (type *)alloc(alignof(type), sizeof_flex(type, member, count)) + +/** Allocate zeroed memory for a flexible struct. */ +#define ZALLOC_FLEX(type, member, count) \ + (type *)zalloc(alignof(type), sizeof_flex(type, member, count)) + +/** + * Alignment-aware realloc(). + * + * @param ptr + * The pointer to reallocate. + * @param align + * The required alignment. + * @param old_size + * The previous allocation size. + * @param new_size + * The new allocation size. + * @return + * The reallocated memory, or NULL on failure. + */ +attr(nodiscard, aligned_alloc(2, 4)) +void *xrealloc(void *ptr, size_t align, size_t old_size, size_t new_size); + +/** Reallocate memory for an array. */ +#define REALLOC_ARRAY(type, ptr, old_count, new_count) \ + (type *)xrealloc((ptr), alignof(type), sizeof_array(type, old_count), sizeof_array(type, new_count)) + +/** Reallocate memory for a flexible struct. */ +#define REALLOC_FLEX(type, member, ptr, old_count, new_count) \ + (type *)xrealloc((ptr), alignof(type), sizeof_flex(type, member, old_count), sizeof_flex(type, member, new_count)) + +/** + * Reserve space for one more element in a dynamic array. + * + * @param ptr + * The pointer to reallocate. + * @param align + * The required alignment. + * @param count + * The current size of the array. + * @return + * The reallocated memory, on both success *and* failure. On success, + * errno will be set to zero, and the returned pointer will have room + * for (count + 1) elements. On failure, errno will be non-zero, and + * ptr will returned unchanged. + */ +attr(nodiscard) +void *reserve(void *ptr, size_t align, size_t size, size_t count); + +/** + * Convenience macro to grow a dynamic array. + * + * @param type + * The array element type. + * @param type **ptr + * A pointer to the array. + * @param size_t *count + * A pointer to the array's size. + * @return + * On success, a pointer to the newly reserved array element, i.e. + * `*ptr + *count++`. On failure, NULL is returned, and both *ptr and + * *count remain unchanged. + */ +#define RESERVE(type, ptr, count) \ + ((*ptr) = reserve((*ptr), alignof(type), sizeof(type), (*count)), \ + errno ? NULL : (*ptr) + (*count)++) + +/** + * An arena allocator for fixed-size types. + * + * Arena allocators are intentionally not thread safe. + */ +struct arena { + /** The list of free chunks. */ + void *chunks; + /** The number of allocated slabs. */ + size_t nslabs; + /** The array of slabs. */ + void **slabs; + /** Chunk alignment. */ + size_t align; + /** Chunk size. */ + size_t size; +}; + +/** + * Initialize an arena for chunks of the given size and alignment. + */ +void arena_init(struct arena *arena, size_t align, size_t size); + +/** + * Initialize an arena for the given type. + */ +#define ARENA_INIT(arena, type) \ + arena_init((arena), alignof(type), sizeof(type)) + +/** + * Free an object from the arena. + */ +void arena_free(struct arena *arena, void *ptr); + +/** + * Allocate an object out of the arena. + */ +attr(malloc(arena_free, 2)) +void *arena_alloc(struct arena *arena); + +/** + * Free all allocations from an arena. + */ +void arena_clear(struct arena *arena); + +/** + * Destroy an arena, freeing all allocations. + */ +void arena_destroy(struct arena *arena); + +/** + * An arena allocator for flexibly-sized types. + */ +struct varena { + /** The alignment of the struct. */ + size_t align; + /** The offset of the flexible array. */ + size_t offset; + /** The size of the flexible array elements. */ + size_t size; + /** Shift amount for the smallest size class. */ + size_t shift; + /** The number of arenas of different sizes. */ + size_t narenas; + /** The array of differently-sized arenas. */ + struct arena *arenas; +}; + +/** + * Initialize a varena for a struct with the given layout. + * + * @param varena + * The varena to initialize. + * @param align + * alignof(type) + * @param min + * sizeof(type) + * @param offset + * offsetof(type, flexible_array) + * @param size + * sizeof(flexible_array[i]) + */ +void varena_init(struct varena *varena, size_t align, size_t min, size_t offset, size_t size); + +/** + * Initialize a varena for the given type and flexible array. + * + * @param varena + * The varena to initialize. + * @param type + * A struct type containing a flexible array. + * @param member + * The name of the flexible array member. + */ +#define VARENA_INIT(varena, type, member) \ + varena_init(varena, alignof(type), sizeof(type), offsetof(type, member), sizeof_member(type, member[0])) + +/** + * Free an arena-allocated flexible struct. + * + * @param varena + * The that allocated the object. + * @param ptr + * The object to free. + * @param count + * The length of the flexible array. + */ +void varena_free(struct varena *varena, void *ptr, size_t count); + +/** + * Arena-allocate a flexible struct. + * + * @param varena + * The varena to allocate from. + * @param count + * The length of the flexible array. + * @return + * The allocated struct, or NULL on failure. + */ +attr(malloc(varena_free, 2)) +void *varena_alloc(struct varena *varena, size_t count); + +/** + * Resize a flexible struct. + * + * @param varena + * The varena to allocate from. + * @param ptr + * The object to resize. + * @param old_count + * The old array lenth. + * @param new_count + * The new array length. + * @return + * The resized struct, or NULL on failure. + */ +attr(nodiscard) +void *varena_realloc(struct varena *varena, void *ptr, size_t old_count, size_t new_count); + +/** + * Grow a flexible struct by an arbitrary amount. + * + * @param varena + * The varena to allocate from. + * @param ptr + * The object to resize. + * @param count + * Pointer to the flexible array length. + * @return + * The resized struct, or NULL on failure. + */ +attr(nodiscard) +void *varena_grow(struct varena *varena, void *ptr, size_t *count); + +/** + * Free all allocations from a varena. + */ +void varena_clear(struct varena *varena); + +/** + * Destroy a varena, freeing all allocations. + */ +void varena_destroy(struct varena *varena); + +#endif // BFS_ALLOC_H |