User:Mrvn/LinkedListBucketHeapImplementation

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Linked List Bucket Implementation

I prefixed all the external functions with mrvn the IRC name of the guy who wrote this implementation. You can find his email and name before at the top of the source.

You should be able to implement any of the standard C library calls with ones of your kernel or your own user space. It has very minimal dependencies.

Usage

    mrvn_memory = malloc(p);
    mrvn_memory_init(mrvn_memory, p);
    p = (uintptr)mrvn_malloc(p);
    mrvn_free((void*)p);

Source

/* 
	Linked List Bucket Heap 2013 Goswin von Brederlow <goswin-v-b@web.de>  
 
*/
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "mrvn.h"
 
typedef struct DList DList;
struct DList {
    DList *next;
    DList *prev;
};
 
// initialize a one element DList
static inline void dlist_init(DList *dlist) {
	//printf("%s(%p)\n", __FUNCTION__, dlist);
    dlist->next = dlist;
    dlist->prev = dlist;
}
 
// insert d2 after d1
static inline void dlist_insert_after(DList *d1, DList *d2) {
	//printf("%s(%p, %p)\n", __FUNCTION__, d1, d2);
    DList *n1 = d1->next;
    DList *e2 = d2->prev;
 
    d1->next = d2;
    d2->prev = d1;
    e2->next = n1;
    n1->prev = e2;
}
 
// insert d2 before d1
static inline void dlist_insert_before(DList *d1, DList *d2) {
	//printf("%s(%p, %p)\n", __FUNCTION__, d1, d2);
    DList *e1 = d1->prev;
    DList *e2 = d2->prev;
 
    e1->next = d2;
    d2->prev = e1;
    e2->next = d1;
    d1->prev = e2;
}
 
// remove d from the list
static inline void dlist_remove(DList *d) {
	//printf("%s(%p)\n", __FUNCTION__, d);
    d->prev->next = d->next;
    d->next->prev = d->prev;
    d->next = d;
    d->prev = d;    
}
 
// push d2 to the front of the d1p list
static inline void dlist_push(DList **d1p, DList *d2) {
	//printf("%s(%p, %p)\n", __FUNCTION__, d1p, d2);
    if (*d1p != NULL) {
	dlist_insert_before(*d1p, d2);
    }
    *d1p = d2;
}
 
// pop the front of the dp list
static inline DList * dlist_pop(DList **dp) {
	//printf("%s(%p)\n", __FUNCTION__, dp);
    DList *d1 = *dp;
    DList *d2 = d1->next;
    dlist_remove(d1);
    if (d1 == d2) {
	*dp = NULL;
    } else {
	*dp = d2;
    }
    return d1;
}
 
// remove d2 from the list, advancing d1p if needed
static inline void dlist_remove_from(DList **d1p, DList *d2) {
	//printf("%s(%p, %p)\n", __FUNCTION__, d1p, d2);
    if (*d1p == d2) {
	dlist_pop(d1p);
    } else {
	dlist_remove(d2);
    }
}
 
#define CONTAINER(C, l, v) ((C*)(((char*)v) - (intptr_t)&(((C*)0)->l)))
#define OFFSETOF(TYPE, MEMBER)  __builtin_offsetof (TYPE, MEMBER)
 
#define DLIST_INIT(v, l) dlist_init(&v->l)
 
#define DLIST_REMOVE_FROM(h, d, l)					\
    {									\
	typeof(**h) **h_ = h, *d_ = d;					\
	DList *head = &(*h_)->l;					\
	dlist_remove_from(&head, &d_->l);					\
	if (head == NULL) {						\
	    *h_ = NULL;							\
	} else {							\
	    *h_ = CONTAINER(typeof(**h), l, head);			\
	}								\
    }
 
#define DLIST_PUSH(h, v, l)						\
    {									\
	typeof(*v) **h_ = h, *v_ = v;					\
	DList *head = &(*h_)->l;					\
	if (*h_ == NULL) head = NULL;					\
	dlist_push(&head, &v_->l);					\
	*h_ = CONTAINER(typeof(*v), l, head);				\
    }
 
#define DLIST_POP(h, l)							\
    ({									\
	typeof(**h) **h_ = h;						\
	DList *head = &(*h_)->l;					\
	DList *res = dlist_pop(&head);					\
	if (head == NULL) {						\
	    *h_ = NULL;							\
	} else {							\
	    *h_ = CONTAINER(typeof(**h), l, head);			\
	}								\
	CONTAINER(typeof(**h), l, res);					\
    })
 
#define DLIST_ITERATOR_BEGIN(h, l, it)					\
    {									\
        typeof(*h) *h_ = h;						\
	DList *last_##it = h_->l.prev, *iter_##it = &h_->l, *next_##it;	\
	do {								\
	    if (iter_##it == last_##it) {				\
		next_##it = NULL;					\
	    } else {							\
		next_##it = iter_##it->next;				\
	    }								\
	    typeof(*h)* it = CONTAINER(typeof(*h), l, iter_##it);
 
#define DLIST_ITERATOR_END(it)						\
	} while((iter_##it = next_##it));				\
    }
 
#define DLIST_ITERATOR_REMOVE_FROM(h, it, l) DLIST_REMOVE_FROM(h, iter_##it, l)
 
typedef struct Chunk Chunk;
struct Chunk {
    DList all;
    int used;
    union {
	char data[0];
	DList free;
    };
};
 
enum {
    NUM_SIZES = 32,
    ALIGN = 4,
    MIN_SIZE = sizeof(DList),
    HEADER_SIZE = OFFSETOF(Chunk, data),
};
 
Chunk *free_chunk[NUM_SIZES] = { NULL };
size_t mem_free = 0;
size_t mem_used = 0;
size_t mem_meta = 0;
Chunk *first = NULL;
Chunk *last = NULL;
 
static void memory_chunk_init(Chunk *chunk) {
	//printf("%s(%p)\n", __FUNCTION__, chunk);
    DLIST_INIT(chunk, all);
    chunk->used = 0;
    DLIST_INIT(chunk, free);
}
 
static size_t memory_chunk_size(const Chunk *chunk) {
	//printf("%s(%p)\n", __FUNCTION__, chunk);
    char *end = (char*)(chunk->all.next);
    char *start = (char*)(&chunk->all);
    return (end - start) - HEADER_SIZE;
}
 
static int memory_chunk_slot(size_t size) {
    int n = -1;
    while(size > 0) {
	++n;
	size /= 2;
    }
    return n;
}
 
void mrvn_memory_init(void *mem, size_t size) {
    char *mem_start = (char *)(((intptr_t)mem + ALIGN - 1) & (~(ALIGN - 1)));
    char *mem_end = (char *)(((intptr_t)mem + size) & (~(ALIGN - 1)));
    first = (Chunk*)mem_start;
    Chunk *second = first + 1;
    last = ((Chunk*)mem_end) - 1;
    memory_chunk_init(first);
    memory_chunk_init(second);
    memory_chunk_init(last);
    dlist_insert_after(&first->all, &second->all);
    dlist_insert_after(&second->all, &last->all);
    // make first/last as used so they never get merged
    first->used = 1;
    last->used = 1;
 
    size_t len = memory_chunk_size(second);
    int n = memory_chunk_slot(len);
    //printf("%s(%p, %#lx) : adding chunk %#lx [%d]\n", __FUNCTION__, mem, size, len, n);
    DLIST_PUSH(&free_chunk[n], second, free);
    mem_free = len - HEADER_SIZE;
    mem_meta = sizeof(Chunk) * 2 + HEADER_SIZE;
}
 
void *mrvn_malloc(size_t size) {
    //printf("%s(%#lx)\n", __FUNCTION__, size);
    size = (size + ALIGN - 1) & (~(ALIGN - 1));
 
	if (size < MIN_SIZE) size = MIN_SIZE;
 
	int n = memory_chunk_slot(size - 1) + 1;
 
	if (n >= NUM_SIZES) return NULL;
 
	while(!free_chunk[n]) {
		++n;
		if (n >= NUM_SIZES) return NULL;
    }
 
	Chunk *chunk = DLIST_POP(&free_chunk[n], free);
    size_t size2 = memory_chunk_size(chunk);
	//printf("@ %p [%#lx]\n", chunk, size2);
    size_t len = 0;
 
	if (size + sizeof(Chunk) <= size2) {
		Chunk *chunk2 = (Chunk*)(((char*)chunk) + HEADER_SIZE + size);
		memory_chunk_init(chunk2);
		dlist_insert_after(&chunk->all, &chunk2->all);
		len = memory_chunk_size(chunk2);
		int n = memory_chunk_slot(len);
		//printf("  adding chunk @ %p %#lx [%d]\n", chunk2, len, n);
		DLIST_PUSH(&free_chunk[n], chunk2, free);
		mem_meta += HEADER_SIZE;
		mem_free += len - HEADER_SIZE;
    }
 
	chunk->used = 1;
    //memset(chunk->data, 0xAA, size);
	//printf("AAAA\n");
    mem_free -= size2;
    mem_used += size2 - len - HEADER_SIZE;
    //printf("  = %p [%p]\n", chunk->data, chunk);
    return chunk->data;
}
 
static void remove_free(Chunk *chunk) {
    size_t len = memory_chunk_size(chunk);
    int n = memory_chunk_slot(len);
    //printf("%s(%p) : removing chunk %#lx [%d]\n", __FUNCTION__, chunk, len, n);
    DLIST_REMOVE_FROM(&free_chunk[n], chunk, free);
    mem_free -= len - HEADER_SIZE;
}
 
static void push_free(Chunk *chunk) {
    size_t len = memory_chunk_size(chunk);
    int n = memory_chunk_slot(len);
    //printf("%s(%p) : adding chunk %#lx [%d]\n", __FUNCTION__, chunk, len, n);
    DLIST_PUSH(&free_chunk[n], chunk, free);
    mem_free += len - HEADER_SIZE;
}
 
void mrvn_free(void *mem) {
    Chunk *chunk = (Chunk*)((char*)mem - HEADER_SIZE);
    Chunk *next = CONTAINER(Chunk, all, chunk->all.next);
    Chunk *prev = CONTAINER(Chunk, all, chunk->all.prev);
 
	//printf("%s(%p): @%p %#lx [%d]\n", __FUNCTION__, mem, chunk, memory_chunk_size(chunk), memory_chunk_slot(memory_chunk_size(chunk)));
    mem_used -= memory_chunk_size(chunk);
 
    if (next->used == 0) {
		// merge in next
		remove_free(next);
		dlist_remove(&next->all);
		//memset(next, 0xDD, sizeof(Chunk));
		mem_meta -= HEADER_SIZE;
		mem_free += HEADER_SIZE;
    }
    if (prev->used == 0) {
		// merge to prev
		remove_free(prev);
		dlist_remove(&chunk->all);
		//memset(chunk, 0xDD, sizeof(Chunk));
		push_free(prev);
		mem_meta -= HEADER_SIZE;
		mem_free += HEADER_SIZE;
    } else {
		// make chunk as free
		chunk->used = 0;
		DLIST_INIT(chunk, free);
		push_free(chunk);
    }
}
 
#define MEM_SIZE (1024*1024*256)
char MEM[MEM_SIZE] = { 0 };
 
#define MAX_BLOCK (1024*1024)
#define NUM_SLOTS 1024
void *slot[NUM_SLOTS] = { NULL };
 
void check(void) {
	int	i;
    Chunk *t = last;
 
	DLIST_ITERATOR_BEGIN(first, all, it) {
		assert(CONTAINER(Chunk, all, it->all.prev) == t);
		t = it;
    } DLIST_ITERATOR_END(it);
 
    for(i = 0; i < NUM_SIZES; ++i) {
		if (free_chunk[i]) {
			t = CONTAINER(Chunk, free, free_chunk[i]->free.prev);
			DLIST_ITERATOR_BEGIN(free_chunk[i], free, it) {
			assert(CONTAINER(Chunk, free, it->free.prev) == t);
			t = it;
			} DLIST_ITERATOR_END(it);
		}
    }
}
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