diosmios/alloc.c

#include "alloc.h"
#include "vsprintf.h"

u8 *RAM;
HeapInfoEntry *HeapInfoEntries=NULL;

extern u32 DRAMRead( u32 a );
extern void DRAMWrite( u32 a, u32 b );

void HeapInit( void )
{
	RAM = (u8*)0xFFFE4000;
	HeapInfoEntries = (HeapInfoEntry*)(RAM+_AHEAP_SIZE);
	memset32( HeapInfoEntries, 0, _AHEAP_INFO_SIZE );

	while( HeapInfoEntries[0].Offset != 0 )
	{
		dbgprintf("Failed to clear memory!");
		Shutdown();
	}

	//dbgprintf("Cleared 0x%04X bytes Space for %d allocs\n", _AHEAP_INFO_SIZE, _AHEAP_INFO_SIZE / 8 );	
}
void *malloc( u32 size )
{
	if( size == 0 )
		return NULL;

	if( size > _AHEAP_SIZE )
		return NULL;

	//align size to 32, easy cheat to allow all allocs to be aligned easily
	size = (size+0x1F) & (~0x1F);

	//find a free entry to be used
	u32 entry = 0xdeadbeef;
	u32 i;

	for( i=0; i < _AHEAP_INFO_SIZE / sizeof(HeapInfoEntry); ++i )
	{
		if( HeapInfoEntries[i].Offset == 0 )
		{
			entry = i;
			break;
		}
	}
	if( entry == 0xdeadbeef )
	{
		dbgprintf("run out of entries!\n");
		return NULL;
	}

	//dbgprintf("Using entry:%d to alloc %d bytes...\n", entry, size );

	//Now we search a used entry
	u32 used_entry = 0xdeadbeef;

	for( i=0; i < _AHEAP_INFO_SIZE / sizeof(HeapInfoEntry); ++i )
	{
		if( HeapInfoEntries[i].Offset == 0 )
			continue;

		used_entry = i;
		break;
	}

	if( used_entry == 0xdeadbeef )
	{
		//dbgprintf("There are no other entries used atm\n");
		HeapInfoEntries[entry].Offset = RAM;
		HeapInfoEntries[entry].Size   = size;
		//dbgprintf("alloc1: ptr:%p size:%08X Entry:%d\n", HeapInfoEntries[entry].Offset, HeapInfoEntries[entry].Size, entry );
		return HeapInfoEntries[entry].Offset;
	}

find_space:
;
	//dbgprintf("[%02d]Offset:%08X Size:%08X\n", used_entry, HeapInfoEntries[used_entry].Offset, HeapInfoEntries[used_entry].Size );

	//now we search for the next closest and the previous closest entry
	u32 next	= 0xdeadbeef;
	u32 prev	= 0xdeadbeef;

	for( i=0; i < _AHEAP_INFO_SIZE / sizeof(HeapInfoEntry); ++i )
	{
		if( HeapInfoEntries[i].Offset == 0 )
			continue;
		if( used_entry == i )
			continue;

		if( next == 0xdeadbeef )
		{
			if( HeapInfoEntries[i].Offset > HeapInfoEntries[used_entry].Offset )
				next = i;
		} else {
			if( HeapInfoEntries[i].Offset < HeapInfoEntries[next].Offset && HeapInfoEntries[i].Offset > HeapInfoEntries[used_entry].Offset )
				next = i;
		}

		if( prev == 0xdeadbeef )
		{
			if( HeapInfoEntries[i].Offset < HeapInfoEntries[used_entry].Offset )
				prev = i;
		} else {
			if( HeapInfoEntries[i].Offset > HeapInfoEntries[prev].Offset && HeapInfoEntries[i].Offset < HeapInfoEntries[used_entry].Offset )
				prev = i;
		}
	}

	if( next == 0xdeadbeef )
	{
		//dbgprintf("This is the last entry\n");
	
		//check if there is engough space left for our alloc

		if( (u32)(HeapInfoEntries[used_entry].Offset-RAM) + HeapInfoEntries[used_entry].Size + size <= _AHEAP_SIZE )
		{
			HeapInfoEntries[entry].Offset = HeapInfoEntries[used_entry].Offset + HeapInfoEntries[used_entry].Size;
			HeapInfoEntries[entry].Size   = size;
			//dbgprintf("alloc2: ptr:%p size:%08X Entry:%d\n", HeapInfoEntries[entry].Offset, HeapInfoEntries[entry].Size, entry );
			return HeapInfoEntries[entry].Offset;
		}
		;//dbgprintf("2Not enough space left only had:%d\n", HEAP_SIZE - ((u32)(HeapInfoEntries[used_entry].Offset-RAM) + HeapInfoEntries[used_entry].Size) );
	} else if( (u32)(HeapInfoEntries[used_entry].Offset) + HeapInfoEntries[used_entry].Size + size < (u32)(HeapInfoEntries[next].Offset) )
	{
		HeapInfoEntries[entry].Offset = HeapInfoEntries[used_entry].Offset + HeapInfoEntries[used_entry].Size;
		HeapInfoEntries[entry].Size   = size;
		//dbgprintf("alloc4: ptr:%p size:%08X Entry:%d\n", HeapInfoEntries[entry].Offset, HeapInfoEntries[entry].Size, entry );
		return HeapInfoEntries[entry].Offset;
	} else {
		;//dbgprintf("4Not enough space left only had:%d %d:%d\n", (u32)( HeapInfoEntries[next].Offset - HeapInfoEntries[used_entry].Offset ) - HeapInfoEntries[used_entry].Size, next, used_entry );
	}

	if( prev == 0xdeadbeef )
	{
		//dbgprintf("This is the first entry\n");
		if( (u32)(HeapInfoEntries[used_entry].Offset-RAM) >= size )
		{
			HeapInfoEntries[entry].Offset = HeapInfoEntries[used_entry].Offset - size;
			HeapInfoEntries[entry].Size   = size;
			//dbgprintf("alloc3: ptr:%p size:%08X Entry:%d\n", HeapInfoEntries[entry].Offset, HeapInfoEntries[entry].Size, entry );
			return HeapInfoEntries[entry].Offset;
		}
		;//dbgprintf("3Not enough space left only had:%d\n", (u32)(HeapInfoEntries[used_entry].Offset-RAM) );
	} else if( (u32)(HeapInfoEntries[prev].Offset) + HeapInfoEntries[prev].Size + size < (u32)(HeapInfoEntries[used_entry].Offset) )
	{
		HeapInfoEntries[entry].Offset = HeapInfoEntries[prev].Offset + HeapInfoEntries[prev].Size;
		HeapInfoEntries[entry].Size   = size;
		//dbgprintf("alloc5: ptr:%p size:%08X Entry:%d\n", HeapInfoEntries[entry].Offset, HeapInfoEntries[entry].Size, entry );
		return HeapInfoEntries[entry].Offset;
	} else {
		;//dbgprintf("5Not enough space left only had:%d\n", (u32)(HeapInfoEntries[used_entry].Offset-HeapInfoEntries[prev].Offset) - HeapInfoEntries[prev].Size );
	}

	//if we land here we have to go to the next entry
	u32 temp = used_entry + 1;
	used_entry = 0xdeadbeef;

	for( i=temp; i < _AHEAP_INFO_SIZE / sizeof(HeapInfoEntry); ++i )
	{
		if( HeapInfoEntries[i].Offset == 0 )
			continue;

		used_entry = i;
		break;
	}

	if( used_entry != 0xdeadbeef )
		goto find_space;

	dbgprintf("failed to alloc %d bytes\n", size  );

	return NULL;
}
void *malloca( u32 size, u32 align )
{
	return malloc( size );
}
void free( void *ptr )
{
	if( ptr == NULL )
		return;

	u32 i;
	for( i=0; i < _AHEAP_INFO_SIZE / sizeof(HeapInfoEntry); ++i )
	{
		if( HeapInfoEntries[i].Offset == ptr )
		{
			//dbgprintf("free:   ptr:%p size:%08X Entry:%d\n", HeapInfoEntries[i].Offset, HeapInfoEntries[i].Size, i );
			HeapInfoEntries[i].Offset = NULL;
			HeapInfoEntries[i].Size = 0;
			ptr = NULL;
			return;
		}
	}
}