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/**
* @file
*
* @brief Initialize a Message Queue
* @ingroup ScoreMessageQueue
*/
/*
* COPYRIGHT (c) 1989-2009.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/score/coremsgimpl.h>
#include <rtems/score/wkspace.h>
/*
* size_t_mult32_with_overflow
*
* This method multiplies two size_t 32-bit numbers and checks
* for overflow. It returns false if an overflow occurred and
* the result is bad.
*/
static inline bool size_t_mult32_with_overflow(
size_t a,
size_t b,
size_t *c
)
{
long long x = (long long)a*b;
if ( x > SIZE_MAX )
return false;
*c = (size_t) x;
return true;
}
bool _CORE_message_queue_Initialize(
CORE_message_queue_Control *the_message_queue,
CORE_message_queue_Disciplines discipline,
uint32_t maximum_pending_messages,
size_t maximum_message_size
)
{
size_t message_buffering_required = 0;
size_t aligned_message_size;
size_t align_mask;
the_message_queue->maximum_pending_messages = maximum_pending_messages;
the_message_queue->number_of_pending_messages = 0;
the_message_queue->maximum_message_size = maximum_message_size;
_CORE_message_queue_Set_notify( the_message_queue, NULL );
/*
* Align up the maximum message size to be an integral multiple of the
* pointer size.
*/
align_mask = sizeof(uintptr_t) - 1;
aligned_message_size = ( maximum_message_size + align_mask ) & ~align_mask;
/*
* Check for an integer overflow. It can occur while aligning up the maximum
* message size.
*/
if (aligned_message_size < maximum_message_size)
return false;
/*
* Calculate how much total memory is required for message buffering and
* check for overflow on the multiplication.
*/
if ( !size_t_mult32_with_overflow(
(size_t) maximum_pending_messages,
aligned_message_size + sizeof(CORE_message_queue_Buffer_control),
&message_buffering_required ) )
return false;
/*
* Attempt to allocate the message memory
*/
the_message_queue->message_buffers = (CORE_message_queue_Buffer *)
_Workspace_Allocate( message_buffering_required );
if (the_message_queue->message_buffers == 0)
return false;
/*
* Initialize the pool of inactive messages, pending messages,
* and set of waiting threads.
*/
_Chain_Initialize (
&the_message_queue->Inactive_messages,
the_message_queue->message_buffers,
(size_t) maximum_pending_messages,
aligned_message_size + sizeof( CORE_message_queue_Buffer_control )
);
_Chain_Initialize_empty( &the_message_queue->Pending_messages );
_Thread_queue_Object_initialize( &the_message_queue->Wait_queue );
if ( discipline == CORE_MESSAGE_QUEUE_DISCIPLINES_PRIORITY ) {
the_message_queue->operations = &_Thread_queue_Operations_priority;
} else {
the_message_queue->operations = &_Thread_queue_Operations_FIFO;
}
return true;
}
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