Thread: Extracting series of hexadecimal values from buffer

Hello All,

I am programming a microcontroller, it get s data from a serial cable 1 byte at a time. It has been programmed to write each received byte to the buffer.

I have functions to write or read a byte from the buffer.

I have the buffer filled with data of about 102 bytes. how can I extract from the 70th byte up to the 82nd byte? the value I need is 12 bytes in total but it starts from the 70th byte?

I will appreciate any help with this task.

below is a sample of the code that removes a byte from the buffer

Code:

/****************************************************************************/
/***        Macro Definitions                                             ***/
/****************************************************************************/
#define CIRCBUFF_PTR_MASK   0x03FFU
#define MAX_CIRCBUFF_SIZE   1024
#define NBR_QUEUES          2
/***********************************************************/
typedef struct
{
    uint16 u16Head;
    uint16 u16Tail;
    uint8  u8Buff[MAX_CIRCBUFF_SIZE];
} tsCircBuff;
typedef enum {RX_QUEUE = 0, TX_QUEUE } eQueueRef;

PRIVATE tsCircBuff sRxQueue, sTxQueue;
PRIVATE const tsCircBuff *apsQueueList[NBR_QUEUES] = { &sRxQueue, &sTxQueue };

PUBLIC uint8 u8SerialQ_RemoveItem(eQueueRef eQueue)
{
    uint8 u8Item = 0;
    tsCircBuff *psQueue;

    psQueue = (tsCircBuff *)apsQueueList[eQueue]; /* Set pointer to the requested queue */

    if (psQueue->u16Tail != psQueue->u16Head)
    {
        /* Data available on queue so remove a single item */
        u8Item = psQueue->u8Buff[psQueue->u16Tail];
        psQueue->u16Tail = (psQueue->u16Tail + 1) & CIRCBUFF_PTR_MASK;
    }
    return(u8Item);
}

If you have access to <string.h> you can use memcpy