readbits.h File Reference

Go to the source code of this file.

Macros
#define	CHAR_BIT   (8)
#define	BITBUF_WIDTH   (sizeof(bit_buffer) * CHAR_BIT)
#define	INIT_BITS
#define	STORE_BITS
#define	RESTORE_BITS
#define	ENSURE_BITS(nbits)
#define	READ_BITS(val, nbits)
#define	READ_MANY_BITS(val, bits)
#define	PEEK_BITS(nbits)   (bit_buffer & ((1 << (nbits))-1))
#define	REMOVE_BITS(nbits)   ((bit_buffer >>= (nbits)), (bits_left -= (nbits)))
#define	INJECT_BITS(bitdata, nbits)
#define	READ_IF_NEEDED

Functions
static int	read_input (BITS_TYPE *p)

Macro Definition Documentation

BITBUF_WIDTH

#define BITBUF_WIDTH   (sizeof(bit_buffer) * CHAR_BIT)

Definition at line 101 of file readbits.h.

CHAR_BIT

#define CHAR_BIT   (8)

Definition at line 99 of file readbits.h.

ENSURE_BITS

#define ENSURE_BITS

(

nbits

)

Value:

    do {                 \
    while (bits_left < (nbits)) READ_BYTES;     \
} while (0)

Definition at line 125 of file readbits.h.

INIT_BITS

#define INIT_BITS

Value:

    do {                          \
    BITS_VAR->i_ptr      = &BITS_VAR->inbuf[0]; \
    BITS_VAR->i_end      = &BITS_VAR->inbuf[0]; \
    BITS_VAR->bit_buffer = 0;                   \
    BITS_VAR->bits_left  = 0;                   \
    BITS_VAR->input_end  = 0;                   \
} while (0)

Definition at line 103 of file readbits.h.

INJECT_BITS

#define INJECT_BITS	(		bitdata,
			nbits
	)

Value:

    ((bit_buffer |= \
    (bitdata) << bits_left), (bits_left += (nbits)))

Definition at line 155 of file readbits.h.

PEEK_BITS

#define PEEK_BITS

(

nbits

)

(bit_buffer & ((1 << (nbits))-1))

Definition at line 153 of file readbits.h.

READ_BITS

#define READ_BITS	(		val,
			nbits
	)

Value:

    do {              \
    ENSURE_BITS(nbits);                         \
    (val) = PEEK_BITS(nbits);                   \
    REMOVE_BITS(nbits);                         \
} while (0)

Definition at line 129 of file readbits.h.

READ_IF_NEEDED

#define READ_IF_NEEDED

Value:

    do {            \
    if (i_ptr >= i_end) {               \
        if (read_input(BITS_VAR))       \
            return BITS_VAR->error;     \
        i_ptr = BITS_VAR->i_ptr;        \
        i_end = BITS_VAR->i_end;        \
    }                                   \
} while (0)

Definition at line 174 of file readbits.h.

READ_MANY_BITS

#define READ_MANY_BITS	(		val,
			bits
	)

Value:

    do {                          \
    unsigned char needed = (bits), bitrun;                      \
    (val) = 0;                                                  \
    while (needed > 0) {                                        \
        if (bits_left <= (BITBUF_WIDTH - 16)) READ_BYTES;       \
        bitrun = (bits_left < needed) ? bits_left : needed;     \
        (val) = ((val) << bitrun) | PEEK_BITS(bitrun);          \
        REMOVE_BITS(bitrun);                                    \
        needed -= bitrun;                                       \
    }                                                           \
} while (0)

Definition at line 135 of file readbits.h.

REMOVE_BITS

#define REMOVE_BITS

(

nbits

)

((bit_buffer >>= (nbits)), (bits_left -= (nbits)))

Definition at line 154 of file readbits.h.

RESTORE_BITS

#define RESTORE_BITS

Value:

    do {               \
    i_ptr      = BITS_VAR->i_ptr;       \
    i_end      = BITS_VAR->i_end;       \
    bit_buffer = BITS_VAR->bit_buffer;  \
    bits_left  = BITS_VAR->bits_left;   \
} while (0)

Definition at line 118 of file readbits.h.

STORE_BITS

#define STORE_BITS

Value:

    do {                 \
    BITS_VAR->i_ptr      = i_ptr;       \
    BITS_VAR->i_end      = i_end;       \
    BITS_VAR->bit_buffer = bit_buffer;  \
    BITS_VAR->bits_left  = bits_left;   \
} while (0)

Definition at line 111 of file readbits.h.

Function Documentation

read_input()

static int read_input ( BITS_TYPE *  p )

static

Definition at line 183 of file readbits.h.

                                    {
    int read = p->sys->read(p->input, &p->inbuf[0], (int)p->inbuf_size);
    if (read < 0) return p->error = MSPACK_ERR_READ;
 
    /* we might overrun the input stream by asking for bits we don't use,
     * so fake 2 more bytes at the end of input */
    if (read == 0) {
        if (p->input_end) {
            D(("out of input bytes"))
            return p->error = MSPACK_ERR_READ;
        }
        else {
            read = 2;
            p->inbuf[0] = p->inbuf[1] = 0;
            p->input_end = 1;
        }
    }
 
    /* update i_ptr and i_end */
    p->i_ptr = &p->inbuf[0];
    p->i_end = &p->inbuf[read];
    return MSPACK_ERR_OK;
}

References D, MSPACK_ERR_OK, MSPACK_ERR_READ, p, and read().