On Tue, May 09, 2000 at 11:22:33AM +0200, andreas.sikkema@xxxxxxxxxxx wrote:
> > (that is, bits 6-7 in byte 2, and bits 0-2 in byte 1, if you
> > consider the 16 bits in bytes 1 and 2 to be a single unit (like an
> > endian-independent uint16), and to count bits from the right)
>
> No, read the bits in the order that they appear.
>
> Example
> 03 80 00 00 00 00 02 FF FF
>
> Suppose the protocol defined for the example is defined as:
> Type: 6 bits
> Subtype: 3 bits
> Padding character: 7 bits
> Padding length: 8 bits
> Data length: 32 bits
> Data: Data length bytes
> Padding: Padding length bytes
>
> What I was thinking about was to retrieve those values like this:
> int type = tvbuff_get_bits( tvbf, 6 );
> int subtype = tvbuff_get_bits( tvbf, 3 );
> char pad_char = tvbuff_get_bits( tvbf, 7 );
> int plength = tv_buff_get_byte( tvbf );
> int dlen = tv_buff_get_bits( tvbf, 32 );
> char* pdata = tv_buff_get_bytes( tvbf, pdata, dlen );
Interesting. I never though to make the tvbuff accessors work sequentially
instead of in a random-access fashion. But I'd like to create a
tvbuff-cursor or iterator to keep track of the current position, rather
than store that in the tvbuff itself. The cursor can keep a pointer to
the tvbuff:
tvbuff_cursor_t tvbc = tvbuff_create_cursor(tvbf)
int type = tvbc_get_bits( tvbc, 6 );
int subtype = tvbc_get_bits( tvbc, 3 );
char pad_char = tvbc_get_bits( tvbc, 7 );
int plength = tvbc_get_bits( tvbc, 8 );
int dlen = tvbc_get_bits( tvbc, 32 );
char* pdata = tvbc_get_bits( tvbc, dlen * 8);
--gilbert
