sdnv.c

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 /**
 * \addtogroup sdnv SDNV Functions
 *
 * @{
 */

/**
 * \file 
 * \brief implementation of SDNV functions
 * \author Georg von Zengen (vonzeng@ibr.cs.tu-bs.de) 
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

#include "logging.h"

#include "agent.h"

/** maximum sdnv length */
#define MAX_LENGTH 8 

int sdnv_encode(uint32_t val, uint8_t* bp, size_t len)
{
        size_t val_len = 0;
        uint32_t tmp = val;

        do {
                tmp = tmp >> 7;
                val_len++;
        } while (tmp != 0);


        if (len < val_len) {
                return -1;
        }

        bp += val_len;
        uint8_t high_bit = 0; // for the last octet
        do {
                --bp;
                *bp = (uint8_t)(high_bit | (val & 0x7f));
                high_bit = (1 << 7); // for all but the last octet
                val = val >> 7;
        } while (val != 0);

        return val_len;
}

size_t sdnv_encoding_len(uint32_t val)
{
        size_t val_len = 0;
//      printf("val %lu ptr %p\n ",val,&val);
        do {
                val = val >> 7;
                val_len++;
        } while (val != 0);
        
        return val_len;
}

int sdnv_decode(const uint8_t* bp, size_t len, uint32_t* val)
{
        LOG(LOGD_DTN, LOG_SDNV, LOGL_DBG, "sdnv_decode");
        const uint8_t* start = bp;
        if (!val) {
                LOG(LOGD_DTN, LOG_SDNV, LOGL_ERR, "SDNV: NULL pointer");
                return -1;
        }
        size_t val_len = 0;
        *val = 0;
        do {
                LOG(LOGD_DTN, LOG_SDNV, LOGL_DBG, "SDNV: len: %u", len);
                if (len == 0){
                        LOG(LOGD_DTN, LOG_SDNV, LOGL_ERR, "SDNV: buffer too short");
                        return -1; // buffer too short
                }
                *val = (*val << 7) | (*bp & 0x7f);
                ++val_len;

                if ((*bp & (1 << 7)) == 0){
                        break; // all done;
                }

                ++bp;
                --len;
        } while (1);

        if ((val_len > MAX_LENGTH) || ((val_len == MAX_LENGTH) && (*start != 0x81))){
                LOG(LOGD_DTN, LOG_SDNV, LOGL_ERR, "SDNV: val_len >= %u", MAX_LENGTH);
                return -1;
        }
        
        LOG(LOGD_DTN, LOG_SDNV, LOGL_DBG, "SDNV: val: %lu", *val);
        return val_len;
}

size_t sdnv_len(const uint8_t* bp)
{
        size_t val_len = 1;
        for ( ; *bp++ & 0x80; ++val_len )
                ;
        return val_len;
}
/** @} */