This is a standard implementation of heap for MushLib. More...

#include "heap.h"
#include "memory.h"
#include "exceptions.h"

Include dependency graph for lib/base/heap.c:

Data Structures
struct	heap_header

struct	heap_block_header

Functions
boolean	is_in_heap (void *structure)

static heap_block_header *	get_header (void *structure)

u_dword	size (void *structure)

precise	occupation ()

static void *	allocate_space (void free_pointer, u_dword size, heap_block_header previous, heap_block_header *next)

static void	handle_allocation_exception ()

void	initialize_heap (void *start_address, u_dword initial_size)

void *	ralloc (u_dword size)

void *	zalloc (u_dword size)

void *	challoc (void *structure, u_dword new_size)

void	unalloc (void *structure)

Variables
heap_header *	header

Detailed Description

This is a standard implementation of heap for MushLib.

The heap doesn't use paging, so it has a limited size. This allows kernel to use it right after launch, but there's also a significant drawback: when kernel heap gets overflown, no standard exception can be shown (because it requires heap space allocation). The drawback is handled with kernel allocation exception handler . Any non-kernel apps may set up their own kernel exception handler (using allocation_exception_id) or just do nothing - default allocation exception handler will allow kernel to terminate safely any app with overflown heap.

Definition in file lib/base/heap.c.

Function Documentation

◆ is_in_heap()

boolean is_in_heap ( void * structure )

Function for determining whether the structure is inside the heap or outside.

Parameters

structure a pointer to the structure.

Returns: true is structure is in heap, false otherwise.

Definition at line 49 of file lib/base/heap.c.

References header.

Referenced by get_header().

◆ get_header()

static heap_block_header * get_header ( void * structure )

static

Internal function for getting heap header of any structure located in heap. It just substracts heap block header size from pointer and casts it to heap block header. Throws heap exception if the given pointer is outside of the current heap.

Parameters

structure a pointer to the structure.

Returns: heap_block_header pointer.

Definition at line 60 of file lib/base/heap.c.

References heap_exception_id, heap_exception_type, and is_in_heap().

Referenced by allocate_space(), challoc(), occupation(), ralloc(), size(), and unalloc().

◆ size()

u_dword size ( void * structure )

Function for structure located in heap size calculation (in bytes). Throws heap exception if the given pointer is outside of the current heap.

Parameters

structure a pointer to the structure.

Returns: structure size (in bytes).

Definition at line 65 of file lib/base/heap.c.

References get_header().

Referenced by allocate_space(), challoc(), ralloc(), and zalloc().

◆ occupation()

precise occupation ( )

Function for heap occupation calculation.

Returns: percent of allocated space in this heap.

Definition at line 69 of file lib/base/heap.c.

References get_header(), and header.

◆ allocate_space()

static void * allocate_space	(	void *	free_pointer,
		u_dword	size,
		heap_block_header *	previous,
		heap_block_header *	next
	)

static

Internal function for space allocation in heap. Sets up and fills heap block header, optionally alters headers of the next and previous heap blocks.

Parameters

free_pointer	pointer to free space (heap block header size + required size).
size	required size of heap block.
previous	previous heap block.
next	next heap block.

Returns: pointer to the start of the block.

Definition at line 95 of file lib/base/heap.c.

References get_header(), and size().

Referenced by ralloc().

◆ handle_allocation_exception()

static void handle_allocation_exception ( )

static

Allocation exception can't be handled regularily: handling requires heap. So, heap exception terminate app without any on-screen explanation.

Definition at line 111 of file lib/base/heap.c.

References heap_exception_id.

Referenced by initialize_heap().

◆ initialize_heap()

void initialize_heap	(	void *	start_address,
		u_dword	initial_size
	)

Function for heap initialization, sets up singleton heap header. This implementation of heap has fixed size, and so doesn't rely on paging. That's enough for kernel and basic app needs, TODO: provide another heap implementation for extended MushLib.

Parameters

start_address	pointer to the start of the heap.
initial_size	initial size of the heap.

Definition at line 116 of file lib/base/heap.c.

References allocation_exception_id, handle_allocation_exception(), and header.

Referenced by _start().

◆ ralloc()

void * ralloc ( u_dword size )

Function for allocation of a raw heap block. Searches for a place of suitable size to fit a structure of requested size in. Throws allocation exception if no free space is available.

Parameters

size	requested block size.

Returns: pointer to the neewly allocated block.

Definition at line 125 of file lib/base/heap.c.

References allocate_space(), allocation_exception_id, allocation_exception_type, get_header(), header, and size().

Referenced by challoc(), and zalloc().

◆ zalloc()

void * zalloc ( u_dword size )

Function for allocation of a heap block and clearing it. Does the same as ralloc, but sets every allocated byte to zero. Throws allocation exception if no free space is available.

Parameters

size	requested block size.

Returns: pointer to the neewly allocated block.

Definition at line 171 of file lib/base/heap.c.

References ralloc(), and size().

◆ challoc()

void * challoc	(	void *	structure,
		u_dword	new_size
	)

Function for heap block size alteration. Attempts to alter size in-place and copys the block only if in-place growth is not available. Throws heap exception if the structure is located outside of the heap.

Parameters

structure	pointer to the structure for allocation size changing.
new_size	new requested size of the structure.

Returns: pointer to the new structure.

Definition at line 177 of file lib/base/heap.c.

References get_header(), ralloc(), size(), and unalloc().

◆ unalloc()

void unalloc ( void * structure )

Function for heap block unallocation. Throws heap exception if the structure is located outside of the heap.

Parameters

structure pointer to the structure for unallocation.

Definition at line 193 of file lib/base/heap.c.

References get_header(), and header.

Referenced by challoc().

Variable Documentation

◆ header

heap_header* header

Header of the current app heap. Every app in MushOS has its own heap. This implementation of heap is a singleton.

Definition at line 46 of file lib/base/heap.c.

Referenced by initialize_heap(), is_in_heap(), occupation(), ralloc(), and unalloc().

Data Structures

Functions

Variables

Detailed Description

Function Documentation

◆ is_in_heap()

◆ get_header()

◆ size()

◆ occupation()

◆ allocate_space()

◆ handle_allocation_exception()

◆ initialize_heap()

◆ ralloc()

◆ zalloc()

◆ challoc()

◆ unalloc()

Variable Documentation

◆ header