//******************************************************************************
// Mailbox system. 
//******************************************************************************
//
// Author: Simon Pickartz,
//	   Chair for Operating Systems,
//	   RWTH Aachen University
// Date:   005/08/2011
//
//******************************************************************************
// 
// Copyright 2010 Intel Corporation
// 
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
// 
//        http://www.apache.org/licenses/LICENSE-2.0
// 
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
// 
//

/**
 * 
 * @file iRCCE_mailbox.c
 * @brief contains implementation of the mailbox system
 * @author Simon Pickartz
 *
 *
 */

#include <metalsvm/stdlib.h>
#include <metalsvm/string.h>

#ifdef CONFIG_ROCKCREEK
#include <asm/iRCCE_lib.h>
#include <asm/irqflags.h>

// forward declaration
static int iRCCE_mailbox_close_one(int rank, int check); 

//------------------------------------------------------------------------------
// FUNCTION: iRCCE_mailbox_print_header
//------------------------------------------------------------------------------
// routine for printing given header (debugging purpose)
//------------------------------------------------------------------------------
/**
 * @brief routine for printing a given header
 * @param header is a pointer to a given iRCCE_MAIL_HEADER structure
*/

void iRCCE_mailbox_print_header(iRCCE_MAIL_HEADER* header) {

                kprintf( "\n"
			"-------------------------\n"
			"| RCK%d\n"
			"-------------------------\n"
                        "| Sender\t: %d\t\n"
                        "| Size\t\t: %d\t\n"
                        "| Tag\t\t: %d\t\n"
			"| Prio\t\t: %d\t\n"
                        "| Payload\t: %s\n" 
			"-------------------------\n\n",
			RCCE_IAM, header->source, 
			header->size, header->tag,
			header->prio, header->payload);
}

//------------------------------------------------------------------------------
// FUNCTION: iRCCE_mail_fetch
//------------------------------------------------------------------------------
/**
 * @brief routine to check for new mail in a given mailbox
 * @param rank is the ID of the ranks mailbox to be emptied 
 *
 * The function checks if the mailbox has new mail for a given rank. In case of
 * new mail it needs memory for the received header. Either there is memory
 * in the internal garbage collection or it has to allocated. The next step is 
 * to check wheter a last-mail was received or a normal one. A last-mail is 
 * indicated by the iRCCE_LAST_MAIL tag. A last-mail entails the appropriate
 * flag in the iRCCE_last_mail array to be set. Otherwise the header has to be
 * enqueued in the mailbox_recv_queue accordingly to the priority field.
 */
//------------------------------------------------------------------------------
static int iRCCE_mail_fetch(
		int rank // rank from whom to empty mailbox
		) {
	/* interrupts should already be disabled! */
	
	iRCCE_MAIL_HEADER* header; 
	
	// check for memory in garbage collection or allocate new 
	if( iRCCE_mail_garbage.first ) {
		header = iRCCE_mail_garbage.first;
		iRCCE_mail_garbage.first = 
			iRCCE_mail_garbage.first->next;
		
		header->next = NULL;
		if( iRCCE_mail_garbage.first == NULL ) {
			iRCCE_mail_garbage.last = NULL;
		}
	} else {
		header = (iRCCE_MAIL_HEADER*)kmalloc(sizeof(iRCCE_MAIL_HEADER));
	}


	// copy header to allocated memory
	//RC_cache_invalidate();
	iRCCE_memcpy_get( (void*)header, (void*)iRCCE_mailbox_recv[rank],
		RCCE_LINE_SIZE );

	// check if received a last-mail
	if( header->tag == iRCCE_LAST_MAIL ) {
		iRCCE_last_mail[rank] = 1;
		iRCCE_mailbox_close_one( rank, 0 ); // we can close respective mailbox
		iRCCE_mail_release( &header );
	} else {
		// check mail priority
		int prio = header->prio;

		// enqueue accordingly 
		header->next = NULL;
		
		if( iRCCE_mailbox_recv_queue[prio].first == NULL ) {
			iRCCE_mailbox_recv_queue[prio].first = header;
			iRCCE_mailbox_recv_queue[prio].last = header;
		}
		else {
			iRCCE_mailbox_recv_queue[prio].last->next = header;
			iRCCE_mailbox_recv_queue[prio].last = header;
		}

	}	


	return iRCCE_SUCCESS;
}


//------------------------------------------------------------------------------
// FUNCTION: iRCCE_mail_check
//------------------------------------------------------------------------------
/** 
 * @brief routine to check one specific mailbox or all
 * @param sender is the core ID from which the mailbox is checked use
 * 	iRCCE_MAILBOX_ALL as wildcard to check all mailboxes
 * 
 * This function may be called by the user application to check one specific
 * mailbox. It is recommended to use it in combination with an inter-core
 * interrupt. It empties one or all mailboxes of the participating cores if the 
 * corresponding sent-flag is set and the mailbox is not closed. After calling 
 * iRCCE_mail_fetch the sent-flag has to be reset. Here we have to use a little 
 * trick because we can only write to the MPB in cacheline granularity. We set
 * the appropriate flag to zero and afterwords touch the MPB on another 
 * cacheline. That causes the write combine buffer to write out the data.
 *
 */
//------------------------------------------------------------------------------
const static iRCCE_MAIL_HEADER dummy_header =
	{0, 0, 0, NULL, 0, 0, 0, {[0 ... iRCCE_MAIL_HEADER_PAYLOAD-1] = 0} }; 

int iRCCE_mail_check(int sender) {
	uint32_t flags;
	int j, i;
	int found = 0;

	// check all mailboxes in case of wildcard
	if( sender == iRCCE_MAILBOX_ALL ) {
		/* disable interrupts */
		flags = irq_nested_disable();

		for( j=1; j<RCCE_NP; ++j ) {
			i = (j+RCCE_IAM)%RCCE_NP;
			
			// only check open mailboxes
			if( iRCCE_mailbox_status[i] == iRCCE_MAILBOX_OPEN ) {
				RC_cache_invalidate();
				if( iRCCE_mailbox_recv[i]->sent ) {
					if( !found ) found = 1;

					iRCCE_mail_fetch(i);
					// reset senders flag
					RC_cache_invalidate();
					*(iRCCE_mailbox_recv[i]) = dummy_header;
				}
			}
		}

		/* enable interrupts */
		irq_nested_enable(flags);

		return (found == 1)? iRCCE_SUCCESS : iRCCE_MAILBOX_EMPTY;
	}

	// verify sender's ID
	if(BUILTIN_EXPECT((sender < 0) || (sender > RCCE_NP) || (sender == RCCE_IAM), 0)) {
		return iRCCE_ERROR_SOURCE;		
	}

	// check if mailbox is open
	if( iRCCE_mailbox_status[sender] == iRCCE_MAILBOX_CLOSED ) {
		return iRCCE_MAILBOX_CLOSED;	
	}

	for(i=0; i<5; i++) {
		RC_cache_invalidate();
		if( iRCCE_mailbox_recv[sender]->sent ) {
			/* disable interrupts */
			flags = irq_nested_disable();

			iRCCE_mail_fetch(sender);

			// reset senders flag
			RC_cache_invalidate();
			*(iRCCE_mailbox_recv[sender]) = dummy_header;
		
			/* enable interrupts */
			irq_nested_enable(flags);

			return iRCCE_SUCCESS;
		}

		NOP8;
	}

	return iRCCE_MAILBOX_EMPTY;
}

//------------------------------------------------------------------------------
// FUNCTION: iRCCE_mail_recv
//------------------------------------------------------------------------------
/** 
 * @brief routine for fetching received headers out of iRCCE_mailbox_recv_queue
 * @param header is the address of a pointer to an iRCCE_MAIL_HEADER structure
 * @return iRCCE_SUCCESS if there was new mail; iRCCE_MAILBOX_EMPTY else
 * @todo implement fairer dequeue mechanism
 *
 * The function checks if the receive queue with highest priority (priority 0) 
 * contains any mail headers. In this case we pop the first element of that list
 * in a FIFO maner. Afterwards the first element of a non-empty receive queue
 * with highest priority is returned.
 */
//------------------------------------------------------------------------------
int iRCCE_mail_recv(
		iRCCE_MAIL_HEADER** header 	// pointer to incoming header 
		) {				// (memory allocated by iRCCE)

	int i, found = 0;
	uint32_t flags;
	iRCCE_MAIL_HEADER* help_header;
	
	// if no mail queued pointer must be ZERO
	*header = NULL;

	/* disable interrupts */	
	flags = irq_nested_disable();

	// check priority queues 
	for( i=0; i<iRCCE_PRIOS; ++i ) {

		if ( iRCCE_mailbox_recv_queue[i].first ) {
			help_header = iRCCE_mailbox_recv_queue[i].first;
			
			iRCCE_mailbox_recv_queue[i].first = 
				iRCCE_mailbox_recv_queue[i].first->next;
				
			if( iRCCE_mailbox_recv_queue[i].first == NULL ) {
				iRCCE_mailbox_recv_queue[i].last = NULL;
			}
		
			/* prepare return value */
			help_header->next = NULL;
			*header = help_header;
			found = 1;
			break;
		}
	
	
	}

	/* enable interrupts */
	irq_nested_enable(flags);
	
	return (found == 1)? iRCCE_SUCCESS : iRCCE_MAILBOX_EMPTY;

}

//------------------------------------------------------------------------------
// FUNCTION: iRCCE_mail_release
//------------------------------------------------------------------------------
/**
 * @brief routine to store released header by user in garbage collection
 * @param header is the address of a pointer to an iRCCE_MAIL_HEADER structure
 * @return iRCCE_SUCCESS in any case
 *
 * This function enqueus a pointer to memory for an iRCCE_MAIL_HEADER structure
 * that is not used by the user program anymore. 'header' points to NULL by 
 * return of the function.
 */
//------------------------------------------------------------------------------
int iRCCE_mail_release(
		iRCCE_MAIL_HEADER** header 
		) {
	uint32_t flags;
	
	/* disable interrupts */
	flags = irq_nested_disable();
	
	// put header in garbage collection
	if( (iRCCE_mail_garbage.first == NULL) 
		&& (iRCCE_mail_garbage.last == NULL ) ) {
		
		iRCCE_mail_garbage.first = *header;
		iRCCE_mail_garbage.last = *header;
	}
	else {
		iRCCE_mail_garbage.last->next = *header;
		iRCCE_mail_garbage.last = *header;
	}
	iRCCE_mail_garbage.last->next = NULL;

	// reset header
	*header = NULL;

	/* enable interrupts */
	irq_nested_enable(flags);

	return iRCCE_SUCCESS;
}

//------------------------------------------------------------------------------
// FUNCTION: iRCCE_mail_send
//------------------------------------------------------------------------------
/**
 * @brief routine to send a mail to a given destination (blocking)
 * @param size is the size of the following message. This message may be
 * contained in the payload or send by an isend()-call
 * @param tag is an integer value to distinguish between different mail types
 * @param prio indicates the priority of the mail. 0 is the highest priority
 * whereas 4 is the lowest.
 * @param payload is a pointer to byte array with a size of 
 * iRCCE_MAIL_HEADER_PAYLOAD. If NULL is passed nothing is done, otherwise array
 * pointed by payload is copied into the header.
 * @param dest indicates the destination of the mail in terms of the ID of 
 * one of the participating ranks
 * @return iRCCE_SUCCESS if send was successful. If target mailbox is closed
 * iRCCE_MAILBOX_CLOESD is returned.
 *
 * First it has to be checked if the target mailbox still contains an unread mail.
 * If this is the case there is time to empty the own mailboxes. It blocks until
 * the receiver has emptied its mailbox. The next step is to acquire the lock 
 * for the target mailbox to be sure that the mailbox is not closed by the 
 * receiver while the mail is delivered. After locking the mailbox an 
 * iRCCE_MAIL_HEADER is generated according with the parameters (but with a 
 * sent-flag set to zero)and is copied into the target mailbox. After all data 
 * beeing written the appropropriate sent-flag has to be set with the same trick
 * already used in iRCCE_mail_check(). Now the lock can be released.
 */
//------------------------------------------------------------------------------
int iRCCE_mail_send(
			size_t size, 	// size of following message expected to be send/received
			int tag,	// tag to indicate message type
			char prio,	// mail priority 
			char* payload,	// pointer to buffer for header payload
			int dest	// UE that will receive the header
			) {
	uint32_t flags;

	// verify sender's ID
	if(BUILTIN_EXPECT((dest < 0) || (dest > RCCE_NP) || (dest == RCCE_IAM),0)) {
		return iRCCE_ERROR_TARGET;		
	}

	// if dest mailbox is full, check for incoming mail
	RC_cache_invalidate();
	while( iRCCE_mailbox_send[dest]->sent ) {
	//	iRCCE_mail_check(iRCCE_MAILBOX_ALL);
		RC_cache_invalidate();
		NOP8;
		NOP8;
		NOP8;
	}

	/* disable interrupts */
	flags = irq_nested_disable();

	// check if mailbox is closed
	RCCE_acquire_lock( dest );
	RC_cache_invalidate();
	if( iRCCE_mailbox_send[dest]->closed ) {
		RCCE_release_lock( dest );
	
		/* enable interrupts */
		irq_nested_enable(flags);
		
		return iRCCE_MAILBOX_CLOSED;
	}	

	// prepare header
	iRCCE_MAIL_HEADER header = { RCCE_IAM, size, tag, NULL, prio,
			RCCE_FLAG_UNSET, RCCE_FLAG_UNSET,
			{[0 ... iRCCE_MAIL_HEADER_PAYLOAD-1] = 0} };

	// payload within the header?
	if( payload ) {
		memcpy( header.payload, payload, iRCCE_MAIL_HEADER_PAYLOAD );
	}	

	// do the actual copy to MPB
	RC_cache_invalidate();
	iRCCE_memcpy_put( (void*)iRCCE_mailbox_send[dest],
			(void*)&header, RCCE_LINE_SIZE );

	// set senders flag
	RC_cache_invalidate();
	iRCCE_mailbox_send[dest]->sent = RCCE_FLAG_SET;
	*(int *)RCCE_fool_write_combine_buffer = 1;			
	RC_cache_invalidate(); 

	RCCE_release_lock( dest );

	/* enable interrupts */
	irq_nested_enable(flags);

	return iRCCE_SUCCESS;
}

//------------------------------------------------------------------------------
// FUNCTION: iRCCE_last_mail_recv
//------------------------------------------------------------------------------
/**
 * @brief check if all final headers are received from all UEs
 * @return iRCCE_SUCCES if all last-mails arrive iRCCE_LAST_MAILS_NOT_RECV
 * otherwise
 *
 * This functions is used to determine if all last-mails arrived at the calling
 * UE. Therefore it checks the iRCCE_last_mail array if all flags are set.
 */
//------------------------------------------------------------------------------
int iRCCE_last_mail_recv(void) {
	int i;
	int res = iRCCE_SUCCESS;

	for( i=0; i<RCCE_NP; ++i ) {
		if( iRCCE_last_mail[i]  == 0 ) {
			res = iRCCE_LAST_MAILS_NOT_RECV;  
			break;
		}
	}

	return res;
}

//------------------------------------------------------------------------------
// FUNCTION: iRCCE_mailbox_wait
//------------------------------------------------------------------------------
/** 
 * @brief wait for all last-mails to be received
 * @return iRCCE_SUCCESS
 *
 * This functions blocks in a loop calling continously iRCCE_last_mail_recv() 
 * until its return value is iRCCE_SUCCESS what implicates that all last-mails
 * of the participating UEs arrived at the calling UE.
 * This function is used to shut down the mailbox environment.
 */
//------------------------------------------------------------------------------
int iRCCE_mailbox_wait(void) {
	while( iRCCE_last_mail_recv() == iRCCE_LAST_MAILS_NOT_RECV ) {
		iRCCE_mail_check(iRCCE_MAILBOX_ALL);
	}

	return iRCCE_SUCCESS;
}


//------------------------------------------------------------------------------
// FUNCTION: iRCCE_mailbox_flush
//------------------------------------------------------------------------------
/**
 * @brief dequeue all iRCCE_mailbox_recv_queue elements and free memory
 * @return iRCCE_SUCCESS
 *
 * This function empties all iRCCE_mailbox_recv_queues whith no regard to their
 * content. This function is used to shut down the mailbox environment.
 */
//------------------------------------------------------------------------------
int iRCCE_mailbox_flush(void) {
	int i;
	uint32_t flags;
	
	/* disable interrupts */
	flags = irq_nested_disable();
	
	// empty priority queues
	for( i=0; i<iRCCE_PRIOS; ++i ) {
		iRCCE_MAIL_HEADER* erase_header = 
			iRCCE_mailbox_recv_queue[i].first;

		while( erase_header != NULL ) {
			iRCCE_mailbox_recv_queue[i].first = 
				iRCCE_mailbox_recv_queue[i].first->next;
			kfree( erase_header, sizeof(iRCCE_MAIL_HEADER) );
			erase_header = iRCCE_mailbox_recv_queue[i].first;
		}

	}

	/* enable interrupts */
	irq_nested_enable(flags);

	return iRCCE_SUCCESS;
}

//------------------------------------------------------------------------------
// FUNCTION: iRCCE_mailbox_close_one
//------------------------------------------------------------------------------
/**
 * @brief routine to close one mailbox
 * @return iRCCE_SUCCESS
 * @param rank is the ID of the ranks mailbox to be closed
 * @param check is a flag indicating wether the mailbox has to be emptied before
 * closing or not. This is required for a close-call as a result of a received
 * last-mail.
 * 
 * This function closes a mailbox of the given rank. If the check flag is set
 * an iRCCE_mail_check()-call is performed. The close procedure has to be 
 * locked to be sure that no UE sends any mail while closing the mailbox.
 */
//------------------------------------------------------------------------------
static int iRCCE_mailbox_close_one(int rank, int check) {
	uint32_t flags;
	RCCE_acquire_lock( RCCE_IAM );
	
	/* disable interrupts */
	flags = irq_nested_disable();

	// check if it contains new mail	
	RC_cache_invalidate();
	if( check && iRCCE_mailbox_recv[rank]->sent ) { 
		
		iRCCE_mail_fetch(rank);

	}

	// close mailbox
	iRCCE_MAIL_HEADER help_header = { 0, 0, 0, NULL, 0, RCCE_FLAG_UNSET,
		RCCE_FLAG_SET, {[0 ... iRCCE_MAIL_HEADER_PAYLOAD-1] = 0} };

	RC_cache_invalidate();
	iRCCE_memcpy_put( (void*)iRCCE_mailbox_recv[rank], 
			&help_header, RCCE_LINE_SIZE );
	
	/* enable interrupts */
	irq_nested_enable(flags);

	RCCE_release_lock( RCCE_IAM );	

	iRCCE_mailbox_status[rank] = iRCCE_MAILBOX_CLOSED;

	return iRCCE_SUCCESS;
}


//------------------------------------------------------------------------------
// FUNCTION: iRCCE_mailbox_close()
//------------------------------------------------------------------------------
/** 
 * @brief routine to close one or all mailboxes
 * @param rank is the ID of the UEs mailbox to be closed if iRCCE_MAILBOX_ALL
 * is passed all mailboxes are closed by the calling UE
 * @return iRCCE_SUCCESS
 *
 * This functions closed one or all mailboxes of the calling UE. This is done by
 * calling iRCCE_mailbox_close_one for one or all mailboxes.
 */
//------------------------------------------------------------------------------
int iRCCE_mailbox_close(int rank) {
	if( rank == iRCCE_MAILBOX_ALL ) {
		int i;
		for( i=0; i<RCCE_NP; ++i ) {
			iRCCE_mailbox_close_one( i, 1 );
		}
	}
	else {
		iRCCE_mailbox_close_one( rank, 1 );
	}

	return iRCCE_SUCCESS;
}

#endif