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How can I install a list in a ARM controller?
typedef struct { volatile unsigned int *p_NextHdr; volatile unsigned int *p_PrevHdr; volatile unsigned int *p_data; }*Hdr;
*p_NextHdr: ptr to the next list element *p_PrevHdr: ptr to the previous list element *p_data: ptr to the buffer (for this list element)
Hdr HdrPtr;
// ptr to the struct
At the beginning:
*p_NextHdr = *p_PrevHdr = *p_data = NULL;
But how can I install a few list elements? Could you tell me the next steps I have to do? How can I allocate storage for the struct?
best regards Ingo
ok that means I use the list as a array and allocate the storage for e.g. 100 structs
struct my_entry my_array[100];
and then I'm able to say
my_array[5].field = 5;
But it is often not needed to be able to traverse a list foward and backward.
My list includes some header information for the incoming data over the ethernet. So the list includes the number of refernces to the buffer, the pointer to the buffer as well as some flags... So the list is only the header of the buffer.
I don't know if it is the best way to install a list - or if there's another better way to do that.
number of list elements with the struct data:
struct data *Header[NB_ETH_RX_PACKETS];
ptr to the tail and the start of the list
struct data *HdrEnd; struct RxData *HdrBegin;
struct data
typedef struct data { volatile unsigned int Data; struct RxData *p_NextHdr; struct RxData *p_PrevHdr; } *Hdr;
Hdr p_HdrLisPtr;
init pointers at the beginning:
HdrBegin->p_PrevHdr = HdrEnd->p_PrevHdr = HdrBegin; /* */ HdrBegin->p_NextHdr = HdrEnd->p_NextHdr = HdrBufEnd; /* */ p_HdrLisPtr = HdrBegin;
so now I should be able to install some list elements in a for-loop (for i=0; i<8; i++)
Header[i]->Data = i; // element in liste eintragen Header[i]->p_PrevHdr = p_HdrLisPtr; /* */ Header[i]->p_NextHdr = p_HdrLisPtr->p_NextHdr; /* */ p_HdrLisPtr->p_NextHdr->p_PrevHdr = Header[i]; /* */ p_HdrLisPtr->p_NextHdr = Header[i];
Are there any mistakes?
Ingo