bin2base32hex.c

// https://tools.ietf.org/html/rfc4648
// https://en.wikipedia.org/wiki/Base32
const char base32_tab[32] = "0123456789ABCDEFGHIJKLMNOPQRSTUV";
int bin2base32hex(uint8_t *buf, int len, char *base32, bool pad)
{
    int i, j, k, cnt = 0;
    uint8_t val = 0;
    int padnum;

    padnum = 8-((len*8+4)/5)%8;

    for(i=0, k=0; i<len; i++){
        for(j=0; j<8; j++){
            if( ( buf[i] & (0x80>>j) ) != 0 ){
                val |= (0x10>>cnt);
            }
            cnt++;
            if( cnt == 5 ){
                base32[k] = base32_tab[val];
                val = 0;
                cnt = 0;
                k++;
            }
        }
    }

    if( cnt > 0 ){
        /* no padding */
        base32[k] = base32_tab[val];
        cnt = 0;
        k++;
    }
    if(pad){
        for(i=0; i<padnum; i++){
            base32[k] = '=';
            k++;
        }
    }

    return k;
}