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#include "arena.h"
#include "shared.h"
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <errno.h>
#include <error.h>
typedef struct an {
void *membase;
void *memcur;
size_t allocated;
size_t used;
struct an *next;
} arenanode;
typedef struct arena {
arenanode *start;
arenanode *current;
// For keeping track of the largest possible thing that can be allocated to one node
// I don't know if I care to keep this or remove it. I'll see if it becomes a problem / is useful
size_t node_memspace;
} arena;
arenanode * arenanode_init(size_t bytes) {
arenanode *an = VALLOC(1, sizeof(*an));
if(!an)
return NULL;
an->allocated = bytes;
an->used = 0;
an->next = NULL;
void *mem = VALLOC(bytes, 1);
if(!mem) {
free(an);
return NULL;
}
an->membase = mem;
an->memcur = mem;
return an;
}
arena * arena_init(size_t bytes) {
if(!ISPOWOF2(MEM_ALIGN_BYTES))
XALLOC_EXIT("<arena_init> \"MEM_ALIGN_BYTES\" is not a power of 2. Refusing to create a new arena", );
if(bytes < 1)
RETURNWERR(EINVAL, NULL);
arena *a = VALLOC(1, sizeof(arena));
if(!a)
return NULL;
a->start = NULL;
a->current = NULL;
a->node_memspace = bytes;
arenanode *base = arenanode_init(bytes);
if(!base) {
free(a);
return NULL;
}
a->start = base;
a->current = base;
return a;
}
void * arena_alloc(arena * const arena, size_t bytes) {
if(!ISPOWOF2(MEM_ALIGN_BYTES))
XALLOC_EXIT("<arena_alloc> \"MEM_ALIGN_BYTES\" is not a power of 2. Refusing to allocate any memory", );
if(!arena)
RETURNWERR(EINVAL, NULL);
if(bytes > arena->node_memspace)
RETURNWERR(ENOMEM, NULL);
if(bytes > ((arena->current)->allocated - (arena->current)->used)) {
arenanode *new = arenanode_init(arena->node_memspace);
if(!new)
return NULL;
arena->current->next = new;
arena->current = new;
}
size_t alignment = MEM_ALIGN(bytes);
size_t offset = bytes + alignment;
void *mem = arena->current->memcur;
arena->current->memcur = (void*)(((uint8_t*)arena->current->memcur) + offset);
arena->current->used += offset;
return mem;
// Note: This implementation assumes that malloc provides already-aligned memory. If it
// doesn't, that sucks and blows everything up
}
int arena_free(arena **arena) {
if(!arena)
RETURNWERR(EINVAL, -1);
if(!(*arena))
RETURNWERR(EINVAL, -1);
(*arena)->current = (*arena)->start;
for(arenanode *n; (*arena)->current != NULL;) {
n = (*arena)->current->next;
free((*arena)->current->membase);
free((*arena)->current);
(*arena)->current = n;
}
free((*arena));
(*arena) = NULL;
return 0;
}
int arena_clear(arena **arena) {
if(!arena)
RETURNWERR(EINVAL, -1);
if(!(*arena))
RETURNWERR(EINVAL, -1);
size_t bytes = (*arena)->node_memspace;
int ret = 0;
if((ret = arena_free(arena)) < 0)
return ret;
(*arena) = arena_init(bytes);
return (!(*arena)) ? -1 : 0;
}
simplearena * simplearena_init(size_t bytes) {
return arena_init(bytes);
}
void * simplearena_alloc(simplearena * const a, size_t bytes) {
// The criteria to allocate new memory in arena_alloc is 'bytes > ((a->current)->allocated - (a->current)->used)', so if this
// is true, just return NULL & set errno
if(!a)
RETURNWERR(EINVAL, NULL);
if(bytes > ((a->current)->allocated - (a->current)->used))
RETURNWERR(ENOMEM, NULL);
return arena_alloc(a, bytes);
}
int simplearena_free(simplearena **a) {
return arena_free(a);
}
int simplearena_clear(simplearena **a) {
return arena_clear(a);
}
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