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gc.c File Reference

Jaune - Ahead of time Java compiler for small systems. More...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "gc.h"

Compounds
struct	_HeapEntry
	Header that appears at the start of each alloced or unallocated block in the heap. More...
struct	_HeapEntryState
	Entry used during garbage collection that tracks the state of a heap entry and is used for searching when finding if a number is a heap pointer. More...
Defines
#define	DEBUGMODE   1
	If set will enable many internal consistency checks.
#define	PROFILEMODE   0
	If set will enable the profiling code and alternative heap reverse lookup algorithims.
#define	INLINE
#define	STATIC
#define	TRACE(_a)
#define	TRACE1(_a)
#define	CHECKINTEGRITY()   _checkIntegrity()
#define	CHECKSORTED(_a, _b)
#define	HEAPASSERT(_a, _msg)   if (!(_a)) { DumpHeapState(); _cassert(_msg " at " __FILE__ ":", __LINE__); }
#define	SETMAGIC(_a)   (_a)->uMagic = HEAPMAGIC
#define	VERIFYMAGIC(_a)   HEAPASSERT((_a)->uMagic == HEAPMAGIC, "Invalid heap object")
#define	IFPROFILE(_a)
#define	ISUSED(pEnt)   (pEnt->uSize & USEDFLAG)
	Returns TRUE if this block is used.
Typedefs
typedef _HeapEntry	HeapEntry
typedef _HeapEntryState	HeapEntryState
	Entry used during garbage collection that tracks the state of a heap entry and is used for searching when finding if a number is a heap pointer.
Enumerations
enum	{ HEAPMAGIC = 0xBEEF, USEDFLAG = 1, TRACEINITIALSIZE = 40, TRACEGROWTHSTEP = 20 }
enum	{ FLAGMARKED = 1, FLAGSCANNED = 2 }
	Flags for the garbage collector. More...
Functions
STATIC INLINE UINT16	_getSize (HeapEntry *pEnt)
	Returns the size in bytes of this block.
void	SetupGarbageCollector (UINT16 *pTopOfStack, void **pStatics, UINT nInStatics)
STATIC void	_checkIntegrity (void)
	Scans the heap and verifies that it is consistent. More...
void	InitHeap (void *pBase, UINT uSize)
	Initialise the heap to use the given memory block. More...
void *	__Alloc (UINT uSize)
	Attempt to allocate a block of memory out of the heap, returning NULL if there is insufficent space. More...
void	Free (void *p)
	Frees a previousally allocated block. More...
UINT	GetAvailableHeap (void)
	Returns a rough estimate of the available heap space. More...
void *	GrowAlloc (void *p, UINT uSize)
	Grows the previousally allocated buffer, copying if the block can't be grown in place. More...
void	DumpHeapState (void)
	Dumps the heap state to stdout.
void	DumpHeapStats (void)
	Dumps the heap statistics to stdout.
STATIC void	_checkSorted (HeapEntryState *pEntries, UINT nEntries)
STATIC void *	_getBase (HeapEntryState *pStates, int iOff)
STATIC HeapEntryState *	_getHeapEntryState (void *p, HeapEntryState *pStates, UINT nStateEntries)
void	_mark (void *p, HeapEntryState *pStates, UINT nStateEntries)
STATIC void	_scanArea (void **pScan, UINT nToScan, HeapEntryState *pStates, UINT nStateEntries)
void	_scanReferenceArray (Array *pArray, HeapEntryState *pStates, UINT nStateEntries)
void	_scanInstance (Instance *pIns, HeapEntryState *pStates, UINT nStateEntries)
void	_scanStringBuffer (StringBuffer *pSB, HeapEntryState *pStates, UINT nStateEntries)
void	_scanHeap (HeapEntryState *pStates, UINT nStateEntries)
UINT	RunGarbageCollector (void)
UINT	RunGarbageCollectorInt (void **pRoot, UINT nInRoot, void **pStatic, UINT nInStatic)
	Runs the garbage collector using the given data as the root set. More...
void	HeapSetSearchMode (UINT u)

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Detailed Description

Jaune - Ahead of time Java compiler for small systems.

Author:

Copyright Michael Hope 2002 <michaelh@juju.net.nz> This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

Id:

gc.c,v 1.1.1.1 2002/04/23 03:42:57 michaelh Exp

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Enumeration Type Documentation

anonymous enum

Enumeration values: HEAPMAGIC  Magic number used in HeapEntry.uMagic. USEDFLAG  Flag used to mark an entry as used. TRACEINITIALSIZE  Initial size of the alloc trace. TRACEGROWTHSTEP  Increment used in growing the alloc trace.

anonymous enum

Flags for the garbage collector. Enumeration values: FLAGMARKED  Marks a heap entry as marked as in it can be reached from the root set. FLAGSCANNED  Marks a heap entry as scanned as in it has been searched by the GC system for references to other objects.

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Function Documentation

void* __Alloc (  UINT    uSize )

Attempt to allocate a block of memory out of the heap, returning NULL if there is insufficent space. Does not zero the memory.

STATIC void _checkIntegrity (  void    )

Scans the heap and verifies that it is consistent. Checks: The next and prev pointers are consistent. If the block is free, the next ptr and size match up. The number of allocated blocks matches the recorded number.

void Free (  void *    p )

Frees a previousally allocated block. Will fail if the passed in pointer is invalid.

UINT GetAvailableHeap (  void    )

Returns a rough estimate of the available heap space. Returns the sum of all free space, which may not be contigious and allocatable.

void* GrowAlloc (  void *    p, UINT    uNewSize )

Grows the previousally allocated buffer, copying if the block can't be grown in place. Zeros the new area. Parameters: p  Base of the current block. If null, equvalient to Alloc()

void InitHeap (  void *    pBase, UINT    uSize )

Initialise the heap to use the given memory block. Completely resets the heap. Note that the total free space will be less than that fed in due to the headers.

UINT RunGarbageCollectorInt (  void **    pRoot, UINT    nInRoot, void **    pStatic, UINT    nInStatic )

Runs the garbage collector using the given data as the root set. Returns the number of blocks that were returned to the free pool.

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Variable Documentation

UINT16 uAlloced

Total number of allocated blocks. Used by the GC to save computing the size of the GC state block.

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