/*

** File: vmem_ref.c

**

** Author: Sean McDermott

**

** Contributor:

**

** Description: This piece of code deals with counting share pages.

** The counting pages are done in a 4Mb pieace of memory

*/

#include "vmem_ref.h"

#include "vmemL2.h"

//initalize the starting address for reference counting array

static Uint32* ref = (Uint32*) REF_START;

void _vmem_ref_init( void )

{

//reserves the addresses in the virtual memory

_vmeml2_static_address( REF_START, REF_END, TRUE);

//marks all entries as empty

int i;

for( i =0; i < REF_SIZE; i++ )

{

ref[i] = REF_EMPTY;

}

c_puts( " vmem_ref");

#ifdef _VMEM_REF_DEBUG

c_printf("Should be 0 %x\n", _vmem_ref_get_count(0x400000, TRUE));

c_printf("Should be 0 %x\n", _vmem_ref_get_count(0x400000, FALSE));

_vmem_ref_inc_count(0x400000, TRUE);

c_printf("Should be 1 %x\n", _vmem_ref_get_count(0x400000, TRUE));

c_printf("Should be 0 %x\n", _vmem_ref_get_count(0x400000, FALSE));

_vmem_ref_inc_count(0x400000, TRUE);

_vmem_ref_inc_count(0x400000, FALSE);

c_printf("Should be 2 %x\n", _vmem_ref_get_count(0x400000, TRUE));

c_printf("Should be 1 %x\n", _vmem_ref_get_count(0x400000, FALSE));

_vmem_ref_dec_count(0x400000, TRUE);

c_printf("Should be 1 %x\n", _vmem_ref_get_count(0x400000, TRUE));

_vmem_ref_dec_count(0x400000, TRUE);

c_printf("Should be 0 %x\n", _vmem_ref_get_count(0x400000, TRUE));

for( ;; )

{

c_printf("Count %d\n", _vmem_ref_get_count(0x400000, TRUE));

_vmem_ref_inc_count(0x400000, TRUE);

}

#endif

}

Uint32 _vmem_ref_get_count( Uint32 address, Uint8 is4Mb )

{

Uint32 addr;

Uint32 temp;

Uint32 mb;

int i;

for( i =0; i < REF_SIZE; i++ )

{

//skip if the page is empty (it there is something present it cannot be 0)

if( ref[i] == 0 )

{

continue;

}

temp = ref[i];

addr = temp & REF_ADDRESS;

mb = temp & REF_4MB;

//address must match and wheather or not it is a 4MB page

if( addr == address && mb == is4Mb )

{

return (temp & REF_COUNT) >> 2;

}

}

return 0x00;

}

void _vmem_ref_inc_count( Uint32 address, Uint8 is4Mb )

{

//loop over all entries

Uint32 addr;

Uint32 temp;

Uint32 mb;

Uint32 value;

int i;

for( i =0; i < REF_SIZE; i++ )

{

//skip if empty

if( ref[i] == 0 )

{

continue;

}

#ifdef _VMEM_REF_DEBUG

c_printf("Found non-empty index %d %x \n", i, ref[i] );

#endif

temp = ref[i];

addr = temp & REF_ADDRESS;

mb = temp & REF_4MB;

//if the address and the correct size is found then

if( addr == address && mb == is4Mb )

{

//get the reference count

value = temp & REF_COUNT;

if( value == REF_COUNT )

{

__panic("Vmem Ref page shared to many times");

}

//increase the reference count by 1

value = value + REF_COUNT_ADD;

//reassemble and put it back in the index

ref[i] = addr | value | REF_VALID | mb;

return;

}

}

//if the address is not found make a new entry for it

for( i =0; i < REF_SIZE; i++ )

{

//skip if there is already an entry

if( ref[i] != 0 )

{

continue;

}

//calulate values and store

ref[i] = ( address & REF_ADDRESS) | (is4Mb & REF_4MB) | REF_COUNT_ADD | REF_VALID;

#ifdef _VMEM_REF_DEBUG

c_printf("Make new entry for addr %x %x\n", address, ref[i] );

#endif

return;

}

__panic( "Vmem Ref out of places for shared pages");

}

void _vmem_ref_dec_count( Uint32 address, Uint8 is4Mb )

{

//loop over all entries

Uint32 addr;

Uint32 temp;

Uint32 mb;

Uint32 value;

int i;

for( i =0; i < REF_SIZE; i++ )

{

//skip blank entries

if( ref[i] == 0 )

{

continue;

}

temp = ref[i];

addr = temp & REF_ADDRESS;

mb = temp & REF_4MB;

//once the address is found which correct page size

if( addr == address && mb == is4Mb )

{

//get reference count

value = temp & REF_COUNT;

//if there is only one refernce clear entry

if( value == REF_COUNT_ADD )

{

#ifdef _VMEM_REF_DEBUG

c_printf("Index %d was delted\n", i);

#endif

ref[i] = REF_EMPTY;

return;

}

#ifdef _VMEM_REF_DEBUG

c_printf("Vmem ref %d %d %d\n", value >> 2, ( value >>2) -1, (( value >>2) -1) <<2 );

#endif

//shift back to normal number

value = value >> 2;

//decrease

value--;

//reshift

value = value << 2;

//reasemble and store

ref[i] = addr | (value & REF_COUNT ) | REF_VALID | mb;

return;

}

}

__panic( "Vmem no page to decrement");

}