Nils O. Selåsdal
130 lines
3.7 KiB
C
130 lines
3.7 KiB
C
#ifndef UC_SARENA_H_
|
|
#define UC_SARENA_H_
|
|
|
|
#include <stddef.h>
|
|
#include <stdint.h>
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
/** @file
|
|
* Static arena allocator.
|
|
*
|
|
* An UCSArena allocates memory from a provided buffer.
|
|
*
|
|
* The backing buffer should be suitable aligned to the types
|
|
* that will be allocated from it. Use .e.g
|
|
* @code
|
|
* _Alignas(16) char mem[1024];
|
|
* @endcode
|
|
* as the backing buffer.
|
|
*
|
|
* Once allocated, a piece of memory obtained from the
|
|
* allocator cannot be free'd individually, only the entire SArena can
|
|
* be free'd/reset
|
|
*/
|
|
typedef struct UCSArena UCSArena;
|
|
struct UCSArena {
|
|
unsigned char *start; // start of user buffer
|
|
unsigned char *curr; // next alloc point
|
|
unsigned char *end; // one past end of user buffer
|
|
int tmp_allocs; // no of uc_sar_tmp_begin calls
|
|
};
|
|
|
|
typedef struct UCSTmpAlloc UCSTmpAlloc;
|
|
struct UCSTmpAlloc {
|
|
unsigned char *alloc_point;
|
|
UCSArena *arena;
|
|
};
|
|
/** Initialize a UCSArena with predefined backing array.
|
|
*
|
|
* @data must be an array type
|
|
* Use as
|
|
* @code
|
|
* _Alignas(16) char v[128];
|
|
* UCSArena a = UC_BV_STATIC_INITIALIZER(v);
|
|
* @endcode
|
|
*/
|
|
#define UC_SAR_STATIC_INITIALIZER(data) UC_SAR_INITIALIZER((data), sizeof(data))
|
|
|
|
/** Initializer for UCSArena with predefined memory
|
|
* Use as
|
|
* @code
|
|
* char v[128];
|
|
* UCSArena a = UC_BV_STATIC_INITIALIZER(v, sizeof v);
|
|
* @endcode
|
|
* or
|
|
* @code
|
|
* char *m = malloc(128);
|
|
* UCSArena a = UC_BV_INIT(m, 128);
|
|
* @endcode
|
|
*/
|
|
#define UC_SAR_INITIALIZER(data, sz) {(data), (data), (data) + sz}
|
|
|
|
/** Initialize a UCSArena with an array as the backing memory to allocate from.
|
|
* The macro can be used at local scope to allocate memory automatic on the stack,
|
|
* or at global scope where the backing array will have static storage duration
|
|
*
|
|
* Use as:
|
|
* @code
|
|
* UC_SAR_ALLOC_DEF(my_allocator, 1024)
|
|
* struct foo *foo = uc_sar_alloc(&my_allocator);
|
|
* if (foo == NULL) {
|
|
* // out of memory
|
|
* }
|
|
* @endcode
|
|
*
|
|
* @note, the backing buffer has alignment of 16. Use manual init if a different alignment
|
|
* is needed.
|
|
* @param var_name Variable name for the allocator
|
|
* @param size_ byte size of the backing array
|
|
*/
|
|
#define UC_SAR_ALLOC_DEF(var_name, size_) \
|
|
struct { \
|
|
_Alignas(16) char memory[size_]; \
|
|
} var_name##_memory; \
|
|
UCSArena var_name = UC_SAR_STATIC_INITIALIZER(var_name##_memory.memory)
|
|
|
|
/** Allocate space for @type_ , returned memory is aligned to requirements
|
|
* of @type.
|
|
*
|
|
* Use as:
|
|
* @code
|
|
* UC_SAR_ALLOC_DEF(my_allocator, 1024)
|
|
* struct foo *foo = UC_SAR_ALLOC_ALIGNED(&my_allocator, struct foo);
|
|
* // Array types can be used too:
|
|
* struct Foo *str = UC_SAR_ALLOC_ALIGNED(&my_allocator, struct Foo[32]);
|
|
* @endcode
|
|
*/
|
|
#define UC_SAR_ALLOC_ALIGNED(allocator, type_) uc_sar_alloc_aligned((allocator), sizeof(type_), _Alignof(type_))
|
|
|
|
// Initialize an UCSArena to allocate from @mem which is @sz bytes
|
|
static inline void uc_sar_init(UCSArena *a, void *mem, size_t sz)
|
|
{
|
|
a->start = a->curr = mem;
|
|
a->end = a->start + sz;
|
|
}
|
|
|
|
// begin temporary allocation. All allocations afterwards will be released in uc_sar_tmp_end
|
|
UCSTmpAlloc uc_sar_tmp_begin(UCSArena *a);
|
|
|
|
// end temporary allocations, releaseing all allocations since the most recent uc_sar_tmp_begin
|
|
void uc_sar_tmp_end(const UCSTmpAlloc *state);
|
|
|
|
// Allocate @sz bytes from the UCSArena. Returns NULL if not enough space
|
|
void *uc_sar_alloc(UCSArena *a, size_t sz);
|
|
|
|
// Allocate @sz bytes from the UCSArena, returned pointer is aligned to @align
|
|
// Returns NULL if not enough space
|
|
void *uc_sar_alloc_aligned(UCSArena *a, size_t sz, unsigned int align) [[gnu::alloc_align(2)]];
|
|
|
|
static inline void uc_sar_reset(UCSArena *a)
|
|
{
|
|
a->curr = a->start;
|
|
}
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif
|