godot/core/allocators.h
2014-02-09 22:10:30 -03:00

199 lines
4.5 KiB
C++

/*************************************************************************/
/* allocators.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* http://www.godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/*************************************************************************/
#ifndef ALLOCATORS_H
#define ALLOCATORS_H
#include "os/memory.h"
template<int PREALLOC_COUNT=64, int MAX_HANDS=8>
class BalloonAllocator {
enum {
USED_FLAG=(1<<30),
USED_MASK=USED_FLAG-1
};
struct Balloon {
Balloon *next;
Balloon *prev;
uint32_t hand;
};
struct Hand {
int used;
int allocated;
Balloon *first;
Balloon *last;
};
Hand hands[MAX_HANDS];
public:
void* alloc(size_t p_size) {
size_t max=(1<<MAX_HANDS);
ERR_FAIL_COND_V( p_size>max, NULL );
unsigned int hand=0;
while(p_size>(size_t)(1<<hand)) ++hand;
Hand &h=hands[hand];
if (h.used==h.allocated) {
for(int i=0;i<PREALLOC_COUNT;i++) {
Balloon *b = (Balloon*)memalloc(sizeof(Balloon)+(1<<hand));
b->hand=hand;
if (h.last) {
b->prev=h.last;
h.last->next=b;
h.last=b;
} else {
b->prev=NULL;
h.last=b;
h.first=b;
}
}
h.last->next=NULL;
h.allocated+=PREALLOC_COUNT;
}
Balloon *pick=h.last;
ERR_FAIL_COND_V( (pick->hand&USED_FLAG), NULL );
// remove last
h.last=h.last->prev;
h.last->next=NULL;
pick->next=h.first;
h.first->prev=pick;
pick->prev=NULL;
h.first=pick;
h.used++;
pick->hand|=USED_FLAG;
return (void*)(pick+1);
}
void free(void* p_ptr) {
Balloon *b=(Balloon*)p_ptr;
b-=1;
ERR_FAIL_COND(!(b->hand&USED_FLAG) );
b->hand=b->hand&USED_MASK; // not used
int hand=b->hand;
Hand &h=hands[hand];
if (b==h.first)
h.first=b->next;
if (b->prev)
b->prev->next=b->next;
if (b->next)
b->next->prev=b->prev;
if (h.last!=b) {
h.last->next=b;
b->prev=h.last;
b->next=NULL;
h.last=b;
}
h.used--;
if (h.used<=(h.allocated-(PREALLOC_COUNT*2))) { // this is done to ensure no alloc/free is done constantly
for(int i=0;i<PREALLOC_COUNT;i++) {
ERR_CONTINUE( h.last->hand& USED_FLAG );
Balloon *new_last=h.last->prev;
if (new_last)
new_last->next=NULL;
memfree( h.last );
h.last=new_last;
}
h.allocated-=PREALLOC_COUNT;
}
}
BalloonAllocator() {
for(int i=0;i<MAX_HANDS;i++) {
hands[i].allocated=0;
hands[i].used=0;
hands[i].first=NULL;
hands[i].last=NULL;
}
}
void clear() {
for(int i=0;i<MAX_HANDS;i++) {
while(hands[i].first) {
Balloon *b=hands[i].first;
hands[i].first=b->next;
memfree(b);
}
hands[i].allocated=0;
hands[i].used=0;
hands[i].first=NULL;
hands[i].last=NULL;
}
}
~BalloonAllocator() {
clear();
}
};
#endif // ALLOCATORS_H