4coder/4coder_mem.h

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#ifndef FCODER_MEM_H
#define FCODER_MEM_H
struct Partition{
char *base;
int pos, max;
};
struct Temp_Memory{
void *handle;
int pos;
};
inline Partition
make_part(void *memory, int size){
Partition partition;
partition.base = (char*)memory;
partition.pos = 0;
partition.max = size;
return partition;
}
inline void*
partition_allocate(Partition *data, int size){
void *ret = 0;
if (size > 0 && data->pos + size <= data->max){
ret = data->base + data->pos;
data->pos += size;
}
return ret;
}
inline void
partition_align(Partition *data, unsigned int boundary){
--boundary;
data->pos = (data->pos + boundary) & (~boundary);
}
inline void*
partition_current(Partition *data){
return data->base + data->pos;
}
inline int
partition_remaining(Partition *data){
return data->max - data->pos;
}
inline Partition
partition_sub_part(Partition *data, int size){
Partition result = {};
void *d = partition_allocate(data, size);
if (d) result = make_part(d, size);
return result;
}
#define push_struct(part, T) (T*)partition_allocate(part, sizeof(T))
#define push_array(part, T, size) (T*)partition_allocate(part, sizeof(T)*(size))
#define push_block(part, size) partition_allocate(part, size)
inline Temp_Memory
begin_temp_memory(Partition *data){
Temp_Memory result;
result.handle = data;
result.pos = data->pos;
return result;
}
inline void
end_temp_memory(Temp_Memory temp){
((Partition*)temp.handle)->pos = temp.pos;
}
/*
NOTE(allen):
This is a very week general purpose allocator system.
It should only be used for infrequent large allocations (4K+).
*/
#include <stdint.h>
#include <assert.h>
#include <string.h>
enum{
MEM_BUBBLE_FLAG_INIT = 0x0,
MEM_BUBBLE_USED = 0x1,
};
struct Bubble{
Bubble *prev;
Bubble *next;
Bubble *prev2;
Bubble *next2;
int32_t size;
uint32_t flags;
uint32_t _unused_[4];
};
struct General_Memory{
Bubble sentinel;
Bubble free_sentinel;
Bubble used_sentinel;
};
struct Mem_Options{
Partition part;
General_Memory general;
};
inline void
insert_bubble(Bubble *prev, Bubble *bubble){
bubble->prev = prev;
bubble->next = prev->next;
bubble->prev->next = bubble;
bubble->next->prev = bubble;
}
inline void
remove_bubble(Bubble *bubble){
bubble->prev->next = bubble->next;
bubble->next->prev = bubble->prev;
}
inline void
insert_bubble2(Bubble *prev, Bubble *bubble){
bubble->prev2 = prev;
bubble->next2 = prev->next2;
bubble->prev2->next2 = bubble;
bubble->next2->prev2 = bubble;
}
inline void
remove_bubble2(Bubble *bubble){
bubble->prev2->next2 = bubble->next2;
bubble->next2->prev2 = bubble->prev2;
}
static void
general_sentinel_init(Bubble *bubble){
bubble->prev = bubble;
bubble->next = bubble;
bubble->prev2 = bubble;
bubble->next2 = bubble;
bubble->flags = MEM_BUBBLE_USED;
bubble->size = 0;
}
static void
general_memory_open(General_Memory *general, void *memory, int32_t size){
general_sentinel_init(&general->sentinel);
general_sentinel_init(&general->free_sentinel);
general_sentinel_init(&general->used_sentinel);
Bubble *first = (Bubble*)memory;
first->flags = (uint32_t)MEM_BUBBLE_FLAG_INIT;
first->size = size - sizeof(Bubble);
insert_bubble(&general->sentinel, first);
insert_bubble2(&general->free_sentinel, first);
}
static int32_t
general_memory_check(General_Memory *general){
Bubble *sentinel = &general->sentinel;
for (Bubble *bubble = sentinel->next;
bubble != sentinel;
bubble = bubble->next){
assert(bubble);
Bubble *next = bubble->next;
assert(bubble == next->prev);
if (next != sentinel && bubble->prev != sentinel){
assert(bubble->next > bubble);
assert(bubble > bubble->prev);
char *end_ptr = (char*)(bubble + 1) + bubble->size;
char *next_ptr = (char*)next;
(void)(end_ptr);
(void)(next_ptr);
assert(end_ptr == next_ptr);
}
}
return(1);
}
#define BUBBLE_MIN_SIZE 1024
static void
general_memory_attempt_split(General_Memory *general, Bubble *bubble, int32_t wanted_size){
int32_t remaining_size = bubble->size - wanted_size;
if (remaining_size >= BUBBLE_MIN_SIZE){
bubble->size = wanted_size;
Bubble *new_bubble = (Bubble*)((char*)(bubble + 1) + wanted_size);
new_bubble->flags = (uint32_t)MEM_BUBBLE_FLAG_INIT;
new_bubble->size = remaining_size - sizeof(Bubble);
insert_bubble(bubble, new_bubble);
insert_bubble2(&general->free_sentinel, new_bubble);
}
}
static void*
general_memory_allocate(General_Memory *general, int32_t size){
void *result = 0;
if (size < BUBBLE_MIN_SIZE) size = BUBBLE_MIN_SIZE;
for (Bubble *bubble = general->free_sentinel.next2;
bubble != &general->free_sentinel;
bubble = bubble->next2){
if (!(bubble->flags & MEM_BUBBLE_USED)){
if (bubble->size >= size){
result = bubble + 1;
bubble->flags |= MEM_BUBBLE_USED;
remove_bubble2(bubble);
insert_bubble2(&general->used_sentinel, bubble);
general_memory_attempt_split(general, bubble, size);
break;
}
}
}
return(result);
}
inline void
general_memory_do_merge(Bubble *left, Bubble *right){
assert(left->next == right);
assert(right->prev == left);
left->size += sizeof(Bubble) + right->size;
remove_bubble(right);
remove_bubble2(right);
}
inline void
general_memory_attempt_merge(Bubble *left, Bubble *right){
if (!(left->flags & MEM_BUBBLE_USED) && !(right->flags & MEM_BUBBLE_USED)){
general_memory_do_merge(left, right);
}
}
static void
general_memory_free(General_Memory *general, void *memory){
Bubble *bubble = ((Bubble*)memory) - 1;
assert(bubble->flags == MEM_BUBBLE_USED);
bubble->flags = 0;
remove_bubble2(bubble);
insert_bubble2(&general->free_sentinel, bubble);
Bubble *prev, *next;
prev = bubble->prev;
next = bubble->next;
general_memory_attempt_merge(bubble, next);
general_memory_attempt_merge(prev, bubble);
}
static void*
general_memory_reallocate(General_Memory *general, void *old, int32_t old_size, int32_t size){
void *result = old;
Bubble *bubble = ((Bubble*)old) - 1;
int32_t additional_space = size - bubble->size;
if (additional_space > 0){
Bubble *next = bubble->next;
if (!(next->flags & MEM_BUBBLE_USED) &&
next->size + sizeof(Bubble) >= additional_space){
general_memory_do_merge(bubble, next);
general_memory_attempt_split(general, bubble, size);
}
else{
result = general_memory_allocate(general, size);
if (old_size) memcpy(result, old, old_size);
general_memory_free(general, old);
}
}
return(result);
}
inline void*
general_memory_reallocate_nocopy(General_Memory *general, void *old, int32_t size){
void *result = general_memory_reallocate(general, old, 0, size);
return(result);
}
#define reset_temp_memory end_temp_memory
#define gen_struct(g, T) (T*)general_memory_allocate(g, sizeof(T), 0)
#define gen_array(g, T, size) (T*)general_memory_allocate(g, sizeof(T)*(size))
#define gen_block(g, size) general_memory_open(g, size, 0)
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#endif