IotStaticMemory_FindFree

Find a free buffer using the "in-use" flags.

    int32_t IotStaticMemory_FindFree( uint32_t * pInUse,
                                      size_t limit );

If a free buffer is found, this function marks the buffer in-use. This function is common to the static memory implementation.

Parameters

[in]	pInUse	The "in-use" flags to search.
[in]	limit	How many flags to check, i.e. the size of pInUse.

Returns

The index of a free buffer; -1 if no free buffers are available.

Example:

// To use this function, first declare two arrays. One provides the statically-allocated
// objects, the other provides flags to determine which objects are in-use.
#define NUMBER_OF_OBJECTS    ...
#define OBJECT_SIZE          ...
static uint32_t _pInUseObjects[ NUMBER_OF_OBJECTS ] = { 0 };
static uint8_t _pObjects[ NUMBER_OF_OBJECTS ][ OBJECT_SIZE ] = { { 0 } }; // Placeholder for objects.

// The function to statically allocate objects. Must have the same signature
// as malloc().
void * Iot_MallocObject( size_t size )
{
    int32_t freeIndex = -1;
    void * pNewObject = NULL;

    // Check that sizes match.
    if( size != OBJECT_SIZE )
    {
        // Get the index of a free object.
        freeIndex = IotStaticMemory_FindFree( _pInUseMessageBuffers,
                                              IOT_MESSAGE_BUFFERS );

        if( freeIndex != -1 )
        {
            pNewBuffer = &( _pMessageBuffers[ freeIndex ][ 0 ] );
        }
    }

    return pNewBuffer;
}