/*
 * khm.c - kernel heap manager implementation.
 *
 * Authors  Ghassan Almaless (2008,2009,2010,2011,2012)
 *          Alain Greiner (2016)
 *
 * Copyright (c)  UPMC Sorbonne Universites
 *
 * This file is part of ALMOS-MKH.
 *
 * ALMOS-MKH is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2.0 of the License.
 *
 * ALMOS-MKH is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <kernel_config.h>
#include <hal_kernel_types.h>
#include <hal_special.h>
#include <spinlock.h>
#include <bits.h>
#include <printk.h>
#include <thread.h>
#include <cluster.h>
#include <page.h>
#include <ppm.h>
#include <khm.h>


////////////////////////////
void khm_init( khm_t * khm )
{
	// check config parameters
	assert( ((CONFIG_PPM_PAGE_SHIFT + CONFIG_PPM_HEAP_ORDER) < 32 ) , __FUNCTION__ ,
	         "CONFIG_PPM_HEAP_ORDER too large" );

	// initialize lock
	spinlock_init( &khm->lock );

	// compute kernel heap size
	intptr_t heap_size = (1 << CONFIG_PPM_HEAP_ORDER) << CONFIG_PPM_PAGE_SHIFT;

	// get kernel heap base from PPM
	page_t * page      = ppm_alloc_pages( CONFIG_PPM_HEAP_ORDER );
	xptr_t   base_xp   = ppm_page2base( XPTR( local_cxy, page ) );
	void   * heap_base = GET_PTR( base_xp );

	// initialize first block (complete heap)
	khm_block_t * block = (khm_block_t *)heap_base;
	block->size = heap_size;
	block->busy = 0;

	// initialize KHM fields
	khm->base    = (intptr_t)heap_base;
	khm->size    = heap_size;
	khm->next    = (intptr_t)heap_base;
}

/////////////////////////////////
void * khm_alloc( khm_t    * khm,
                  uint32_t   size )
{
	khm_block_t  * current;
	khm_block_t  * next;
	uint32_t       effective_size;

	// compute actual block size
	effective_size = size + sizeof(khm_block_t);
	effective_size = ARROUND_UP( effective_size, CONFIG_CACHE_LINE_SIZE );

	// get lock protecting heap
	spinlock_lock( &khm->lock );

	// define a starting block to scan existing blocks
	if( ((khm_block_t*)khm->next)->size < effective_size ) current = (khm_block_t*)khm->base;
	else                                                   current = (khm_block_t*)khm->next;

	// scan all existing blocks to find a free block large enough
	while( current->busy || (current->size < effective_size))
	{
		// get next block pointer
		current = (khm_block_t*)((char*)current + current->size);

		if( (intptr_t)current >= (khm->base + khm->size) )  // heap full
		{
			spinlock_unlock(&khm->lock);

			printk("\n[ERROR] in %s : failed to allocate block of size %d\n",
			       __FUNCTION__ , effective_size );
			return NULL;
		}
	}

	// split the current block if it is too large
	if( (current->size - effective_size) >= CONFIG_CACHE_LINE_SIZE )
	{
		// update new free block features
		next           = (khm_block_t *)((char*)current + effective_size);
		next->size     = current->size - effective_size;
		next->busy     = 0;

		// register new free block
		khm->next = (intptr_t)next;

		// update allocated block features
		current->size  = effective_size;
		current->busy  = 1;
	}
	else
	{
		// change block state
		current->busy  = 1;
	}

	// release lock protecting heap
	spinlock_unlock( &khm->lock );

	return (char*)current + sizeof(khm_block_t);
}

///////////////////////////
void khm_free( void * ptr )
{
	khm_t * khm = &LOCAL_CLUSTER->khm;

	khm_block_t * current;
	khm_block_t * next;

	if(ptr == NULL) return;

	current = (khm_block_t *)((char*)ptr - sizeof(khm_block_t));

	// get lock protecting heap
	spinlock_lock(&khm->lock);

	assert( (current->busy == 1) , __FUNCTION__ , "page already freed" );

	// release block
	current->busy = 0;

	// try to merge released block with the next
	while ( 1 )
	{
		next = (khm_block_t*)((char*)current + current->size);
		if ( ((intptr_t)next >= (khm->base + khm->size)) || (next->busy == 1) ) break;
		current->size += next->size;
	}

	if( (intptr_t)current < khm->next ) khm->next = (intptr_t)current;

	// release lock protecting heap
	spinlock_unlock( &khm->lock );
}

