buddy.c File Reference

Buddy-system memory allocator implementation.

#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include <string.h>
#include <ross.h>
#include "buddy.h"

Go to the source code of this file.

Macros
#define	BUDDY_BLOCK_ORDER   6
	Minimum block order.

Functions
unsigned int	next_power2 (unsigned int v)
int	dump_buddy_table (buddy_list_bucket_t *buddy_master)
int	buddy_try_merge (buddy_list_t *blt)
void	buddy_free (void *ptr)
static void	buddy_split (buddy_list_bucket_t *bucket)
void *	buddy_alloc (unsigned size)
buddy_list_bucket_t *	create_buddy_table (unsigned int power_of_two)

Variables
static void *	buddy_base_address = 0

Macro Definition Documentation

BUDDY_BLOCK_ORDER

#define BUDDY_BLOCK_ORDER   6

Definition at line 13 of file buddy.c.

Referenced by create_buddy_table(), and next_power2().

Function Documentation

buddy_alloc()

void * buddy_alloc

(

unsigned

size

)

Find the smallest block that will contain size and return it. Note this returns the memory allocated and usable, not the entire buffer. This may involve breaking up larger blocks.

Parameters

size	The size of the data this allocation must be able to hold.

Definition at line 234 of file buddy.c.

References buddy_split(), buddy_list_bucket::count, g_tw_buddy_master, INVALID, buddy_list_bucket::is_valid, next_power2(), buddy_list_bucket::order, tw_error(), TW_LOC, buddy_list::use, and USED.

Referenced by tw_snapshot_delta().

buddy_free()

void buddy_free

(

void *

ptr

)

Free the given pointer (and coalesce it with its buddy if possible).

Parameters

ptr	The pointer to free.

Definition at line 137 of file buddy.c.

References buddy_try_merge(), buddy_list_bucket::count, FREE, g_tw_buddy_master, buddy_list_bucket::order, buddy_list::size, TW_LOC, tw_printf(), buddy_list::use, and USED.

Referenced by tw_event_free(), tw_event_rollback(), and tw_eventq_push_list().

buddy_split()

void buddy_split ( buddy_list_bucket_t * bucket )

static

This function assumes that a block of the specified order exists.

Parameters

bucket

The bucket containing a block we intend to split.

Definition at line 197 of file buddy.c.

References buddy_list_bucket::count, FREE, buddy_list_bucket::order, buddy_list::size, and buddy_list::use.

Referenced by buddy_alloc().

buddy_try_merge()

int buddy_try_merge

(

buddy_list_t *

blt

)

See if we can merge. If we can, see if we can merge again.

Definition at line 80 of file buddy.c.

References buddy_base_address, buddy_list_bucket::count, FREE, g_tw_buddy_master, buddy_list_bucket::order, buddy_list::size, and buddy_list::use.

Referenced by buddy_free().

create_buddy_table()

buddy_list_bucket_t * create_buddy_table

(

unsigned int

power_of_two

)

Pass in the power of two e.g., passing 5 will yield 2^5 = 32.

Parameters

power_of_two

The largest "order" this table will support.

<Minimum block order

<Minimum block order

<Minimum block order

<Minimum block order

Definition at line 288 of file buddy.c.

References buddy_base_address, BUDDY_BLOCK_ORDER, buddy_list_bucket::count, FREE, INVALID, buddy_list_bucket::is_valid, buddy_list_bucket::order, buddy_list::size, tw_calloc(), TW_LOC, buddy_list::use, and VALID.

Referenced by setup_pes().

dump_buddy_table()

int dump_buddy_table

(

buddy_list_bucket_t *

buddy_master

)

Definition at line 41 of file buddy.c.

References FREE, INVALID, next_power2(), buddy_list::size, buddy_list::use, and VALID.

next_power2()

unsigned int next_power2

(

unsigned int

v

)

Finds the next power of 2 or, if v is a power of 2, return that. From http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2

Parameters

v	Find a power of 2 >= v.

<Minimum block order

<Minimum block order

Definition at line 23 of file buddy.c.

References BUDDY_BLOCK_ORDER.

Referenced by buddy_alloc(), and dump_buddy_table().

Variable Documentation

buddy_base_address

void* buddy_base_address = 0

static

Definition at line 15 of file buddy.c.

Referenced by buddy_try_merge(), and create_buddy_table().