sark_alloc.c File Reference

Memory management routines for SARK. More...

#include <sark.h>

Macros
#define	FREE_MASK   0xe0ff
	Mask used to pick out whether a block is allocated and allocated to a particular application instance.

Functions
void *	sark_xalloc (heap_t *heap, uint size, uint tag, uint flag)
	Allocate a memory block from the specified heap.
void *	sark_alloc (uint count, uint size)
	Allocate a block of memory of count × size bytes from the DTCM heap. Returns either a pointer to the block on success, or NULL on failure.
void	sark_xfree (heap_t *heap, void *ptr, uint flag)
	Free a memory block in the specified heap.
void	sark_free (void *ptr)
	Frees a block of memory which was previously allocated by sark_alloc() (i.e., from the DTCM heap).
uint	sark_xfree_id (heap_t *heap, uint app_id, uint lock)
	Free all allocated blocks in the specified heap which are tagged with the given "app_id".
uint	sark_heap_max (heap_t *heap, uint flag)
	Search the supplied heap and return the size of the largest free block (in bytes).
heap_t *	sark_heap_init (uint *base, uint *top)
	Initialise an area of memory as a heap.
uint	rtr_alloc_id (uint size, uint app_id)
	Allocate a block of entries in the router multicast table (and associate the supplied app_id with this block).
uint	rtr_alloc (uint size)
	Allocate a block of entries in the router multicast table (and associate the caller's app_id with this block).
void	rtr_free (uint entry, uint clear)
	Free a block of MC table entries which starts with the supplied entry. The relevant router registers can be optionally re-initialised.
uint	rtr_free_id (uint app_id, uint clear)
	Free all allocated blocks in the router which are tagged with the given "app_id".
uint	rtr_alloc_max (void)
	Return the size of the largest free block in the router multicast table (or zero if table is full).
void *	sark_tag_ptr (uint tag, uint app_id)
	Get a pointer to a tagged allocation.

Detailed Description

Memory management routines for SARK.

Copyright

© The University of Manchester - 2009-2013

Author

Steve Temple, APT Group, School of Computer Science

Function Documentation

sark_xalloc()

void * sark_xalloc	(	heap_t *	heap,
		uint	size,
		uint	tag,
		uint	flag
	)

Allocate a memory block from the specified heap.

The block will be tagged with the supplied "tag" which must be <= 255. Returns NULL on failure (not enough memory, bad tag or tag in use).

The flag parameter contains two flags in the bottom two bits. If bit 0 is set (ALLOC_LOCK), the heap manipulation is done behind a lock with interrupts disabled. If bit 1 is set (ALLOC_ID), the block is tagged with the AppID provided in bits 15:8 of the flag, otherwise the AppID of the current application is used.

The 8-bit tag is combined with the AppID and stored in the "free" field while the block is allocated. If the tag is non-zero, the block is only allocated if the tag is not in use. The tag (and AppID) is stored in the "alloc_tag" table while the block is allocated.

If this command is used to allocate for an app-id which isn't the caller's, the user should set sv->app_data[app_id].clean to 0 for the application concerned. This ensures that the memory will be cleaned up by a stop signal.

Parameters

[in]	heap	the heap from which the block should be allocated
[in]	size	the size of the block in bytes
[in]	tag	8-bit tag
[in]	flag	flags to control locking and AppID

Returns

pointer to allocated block or NULL on failure

sark_alloc()

void * sark_alloc	(	uint	count,
		uint	size
	)

Allocate a block of memory of count × size bytes from the DTCM heap. Returns either a pointer to the block on success, or NULL on failure.

The total amount of memory available for allocation is around 62KB less all of the static variables used by the application.

Parameters

[in]	count	number of sub-blocks to allocate
[in]	size	size of each sub-block

Returns

pointer to block or NULL

sark_xfree()

void sark_xfree	(	heap_t *	heap,
		void *	ptr,
		uint	flag
	)

Free a memory block in the specified heap.

If the lock bit in the flag parameter is set, the manipulation of the heap is done behind a lock. This will turn interrupts off for some time while the heap is searched. If a NULL pointer (ptr) is passed in, a runtime error will occur. If there is an "alloc_tag" entry associated with the block it is set to NULL.

Parameters

[in]	heap	the heap to which the free block should be returned
[in]	ptr	a pointer to the memory block to be freed
[in]	flag	bit 0 set if the heap should be locked during free

sark_free()

void sark_free

(

void *

ptr

)

Frees a block of memory which was previously allocated by sark_alloc() (i.e., from the DTCM heap).

Parameters

[in]

ptr

pointer to memory block

sark_xfree_id()

uint sark_xfree_id	(	heap_t *	heap,
		uint	app_id,
		uint	flag
	)

Free all allocated blocks in the specified heap which are tagged with the given "app_id".

The flag parameter specifies if locking is needed in the sark_xfree() call. Returns the number of blocks freed.

Parameters

[in]	heap	the heap from which blocks should be freed
[in]	app_id	the AppID whose block should be freed
[in]	flag	controls locking of heap transactions

Returns

number of blocks freed

sark_heap_max()

uint sark_heap_max	(	heap_t *	heap,
		uint	flag
	)

Search the supplied heap and return the size of the largest free block (in bytes).

The flag parameter allows the heap to be locked while the search takes place.

Parameters

[in]	heap	the heap to be searched
[in]	flag	controls locking of heap transactions

Returns

size of largest block

sark_heap_init()

heap_t * sark_heap_init	(	uint *	base,
		uint *	top
	)

Initialise an area of memory as a heap.

Arguments are (uint) pointers to base and top of the area. Returns a pointer to the heap (same address as the base). Assumes the area is large enough to hold a minimal heap (a zero size heap needs 28 bytes).

Parameters

[in]	base	pointer to bottom of heap memory
[in]	top	pointer to top of heap memory

Returns

pointer to heap

rtr_alloc_id()

uint rtr_alloc_id	(	uint	size,
		uint	app_id
	)

Allocate a block of entries in the router multicast table (and associate the supplied app_id with this block).

If this command is used to allocate for an app-id which isn't the caller's, the user should set sv->app_data[app_id].clean to 0 for the application concerned. This ensures that the memory will be cleaned up by a stop signal.

Parameters

[in]	size	number of entries to allocate
[in]	app_id	AppID associated with block

Returns

index of first entry in block on success, zero on failure.

rtr_alloc()

uint rtr_alloc

(

uint

size

)

Allocate a block of entries in the router multicast table (and associate the caller's app_id with this block).

Parameters

[in]

size

number of entries to allocate

Returns

index of first entry in block on success, zero on failure.

rtr_free()

void rtr_free	(	uint	entry,
		uint	clear
	)

Free a block of MC table entries which starts with the supplied entry. The relevant router registers can be optionally re-initialised.

Parameters

[in]	entry	first entry in the block (as returned by rtr_alloc)
[in]	clear	non-zero to cause router registers to be re-initialised

rtr_free_id()

uint rtr_free_id	(	uint	app_id,
		uint	clear
	)

Free all allocated blocks in the router which are tagged with the given "app_id".

The relevant router registers can be optionally re-initialised. Returns number of blocks freed.

Parameters

[in]	app_id	AppID whose entries are to be freed
[in]	clear	non-zero to cause router registers to be re-initialised

Returns

number of blocks freed

rtr_alloc_max()

uint rtr_alloc_max

(

void

)

Return the size of the largest free block in the router multicast table (or zero if table is full).

Returns

number of entries in largest block

sark_tag_ptr()

void * sark_tag_ptr	(	uint	tag,
		uint	app_id
	)

Get a pointer to a tagged allocation.

Parameters

[in]	tag	The tag of the allocation to get a pointer to
[in]	app_id	AppID whose tagged allocation to read (or 0 to use the current core's app ID)

Returns

A pointer to the first allocation found with the given tag, or NULL if no such allocation exists.