bitstream.c File Reference

#include "bitstream.h"

Include dependency graph for bitstream.c:

Go to the source code of this file.

Classes
struct	s_bitstream

Typedefs
typedef struct s_bitstream	bs

Functions
int	bs_attach (bitstream_t *b, u_char *buf, int blen)
int	bs_bytes_used (bitstream_t *b)
int	bs_create (bitstream_t **ppb)
int	bs_destroy (bitstream_t **ppb)
u_char	bs_get (bitstream_t *b, uint8_t nbits)
int	bs_put (bitstream_t *b, u_char bits, uint8_t nbits)

Typedef Documentation

bs

typedef struct s_bitstream bs

Function Documentation

bs_attach()

int bs_attach	(	bitstream_t *	b,
		u_char *	buf,
		int	blen )

Definition at line 41 of file bitstream.c.

{
        b->buf = b->pos = buf;
        b->remain = 8;
        b->len = blen;
        memset(b->buf, 0, b->len);
        return TRUE;
}

References s_bitstream::buf, s_bitstream::len, s_bitstream::pos, s_bitstream::remain, and TRUE.

Referenced by test_bitstream().

bs_bytes_used()

int bs_bytes_used

(

bitstream_t *

b

)

Definition at line 102 of file bitstream.c.

{
        unsigned int used = (unsigned int)(b->pos - b->buf);
        if (b->remain != 8) {
                used++;
        }
        return used;
}

References s_bitstream::buf, s_bitstream::pos, and s_bitstream::remain.

bs_create()

int bs_create

(

bitstream_t **

ppb

)

Definition at line 23 of file bitstream.c.

{
        bs *pb;
        pb = (bs *) malloc(sizeof(bs));
        if (pb) {
                memset(pb, 0, sizeof(bs));
                *ppb = pb;
                return TRUE;
        }
        return FALSE;
}

References FALSE, and TRUE.

Referenced by test_bitstream().

bs_destroy()

int bs_destroy

(

bitstream_t **

ppb

)

Definition at line 35 of file bitstream.c.

{
        free(*ppb);
        return TRUE;
}

References TRUE.

Referenced by test_bitstream().

bs_get()

u_char bs_get	(	bitstream_t *	b,
		uint8_t	nbits )

Definition at line 74 of file bitstream.c.

{
        u_char out;
 
        if (b->remain == 0) {
                b->pos++;
                b->remain = 8;
        }
 
        if (nbits > b->remain) {
                /* Get high bits */
                out = *b->pos;
                out <<= (8 - b->remain);
                out >>= (8 - nbits);
                b->pos++;
                b->remain += 8 - nbits;
                out |= (*b->pos) >> b->remain;
        } else {
                out = *b->pos;
                out <<= (8 - b->remain);
                out >>= (8 - nbits);
                b->remain -= nbits;
        }
 
        assert((unsigned int)(b->pos - b->buf) <= b->len);
        return out;
}

References s_bitstream::buf, s_bitstream::len, s_bitstream::pos, and s_bitstream::remain.

bs_put()

int bs_put	(	bitstream_t *	b,
		u_char	bits,
		uint8_t	nbits )

Definition at line 50 of file bitstream.c.

{
        assert(nbits != 0 && nbits <= 8);
 
        if (b->remain == 0) {
                b->pos++;
                b->remain = 8;
        }
 
        if (nbits > b->remain) {
                unsigned int over = nbits - b->remain;
                (*b->pos) |= (bits >> over);
                b->pos++;
                b->remain = 8 - over;
                (*b->pos) = (bits << b->remain);
        } else {
                (*b->pos) |= bits << (b->remain - nbits);
                b->remain -= nbits;
        }
 
        assert((unsigned int)(b->pos - b->buf) <= b->len);
        return TRUE;
}

References s_bitstream::buf, s_bitstream::len, s_bitstream::pos, s_bitstream::remain, and TRUE.

Referenced by test_bitstream().