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#include <assert.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include "log.h"
#include "mem.h"
#ifndef DEFAULT_ALIGNMENT
#define DEFAULT_ALIGNMENT (2 * sizeof(void*))
#endif
// --- Arena
void* arena_alloc_align(arena* a, size_t size, size_t align) {
ptrdiff_t padding = -(uintptr_t)a->curr & (align - 1);
ptrdiff_t available = a->end - a->curr - padding;
// TRACE("Padding %td available %td", padding, available);
if (available < 0 || (ptrdiff_t)size > available) {
ERROR_EXIT("Arena ran out of memory\n");
}
void* p = a->curr + padding;
a->curr += padding + size;
return memset(p, 0, size);
}
void* arena_alloc(arena* a, size_t size) { return arena_alloc_align(a, size, DEFAULT_ALIGNMENT); }
arena arena_create(void* backing_buffer, size_t capacity) {
return (arena){ .begin = backing_buffer,
.curr = backing_buffer,
.end = backing_buffer + (ptrdiff_t)capacity };
}
void arena_free_all(arena* a) {
a->curr = a->begin; // pop everything at once and reset to the start.
}
void arena_free_storage(arena* a) { free(a->begin); }
arena_save arena_savepoint(arena* a) {
arena_save savept = { .arena = a, .savepoint = a->curr };
return savept;
}
void arena_rewind(arena_save savepoint) { savepoint.arena->curr = savepoint.savepoint; }
// --- Pool
void_pool void_pool_create(arena* a, const char* debug_label, u64 capacity, u64 entry_size) {
size_t memory_requirements = capacity * entry_size;
void* backing_buf = arena_alloc(a, memory_requirements);
assert(entry_size >= sizeof(void_pool_header)); // TODO: create my own assert with error message
void_pool pool = { .capacity = capacity,
.entry_size = entry_size,
.count = 0,
.backing_buffer = backing_buf,
.free_list_head = NULL,
.debug_label = debug_label };
void_pool_free_all(&pool);
return pool;
}
void void_pool_free_all(void_pool* pool) {
// set all entries to be free
for (u64 i = 0; i < pool->capacity; i++) {
void* ptr = &pool->backing_buffer[i * pool->entry_size];
void_pool_header* free_node =
(void_pool_header*)ptr; // we reuse the actual entry itself to hold the header
if (i == (pool->capacity - 1)) {
// if the last one we make its next pointer NULL indicating its full
free_node->next = NULL;
}
free_node->next = pool->free_list_head;
// now the head points to this entry
pool->free_list_head = free_node;
}
}
void* void_pool_get(void_pool* pool, u32 raw_handle) {
// An handle is an index into the array essentially
void* ptr = pool->backing_buffer + (raw_handle * pool->entry_size);
return ptr;
}
void* void_pool_alloc(void_pool* pool, u32* out_raw_handle) {
// get the next free node
if (pool->count == pool->capacity) {
WARN("Pool is full!");
return NULL;
}
if (pool->free_list_head == NULL) {
ERROR("%s Pool is full (head = null)", pool->debug_label);
return NULL;
}
void_pool_header* free_node = pool->free_list_head;
// What index does this become?
uintptr_t start = (uintptr_t)pool->backing_buffer;
uintptr_t cur = (uintptr_t)free_node;
TRACE("%ld %ld ", start, cur);
assert(cur > start);
u32 index = (u32)((cur - start) / pool->entry_size);
/* printf("Index %d\n", index); */
if (out_raw_handle != NULL) {
*out_raw_handle = index;
}
pool->free_list_head = free_node->next;
memset(free_node, 0, pool->entry_size);
pool->count++;
return (void*)free_node;
}
void void_pool_dealloc(void_pool* pool, u32 raw_handle) {
// push free node back onto the free list
void* ptr = void_pool_get(pool, raw_handle);
void_pool_header* freed_node = (void_pool_header*)ptr;
freed_node->next = pool->free_list_head;
pool->free_list_head = freed_node;
pool->count--;
}
u32 void_pool_insert(void_pool* pool, void* item) {
u32 raw_handle;
void* item_dest = void_pool_alloc(pool, &raw_handle);
memcpy(item_dest, item, pool->entry_size);
return raw_handle;
}
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