bit_input.c

算术码编码代码源程序

/* BIT INPUT ROUTINES. */

#include <stdio.h>


/* THE BIT BUFFER. */

static int buffer;		/* Bits waiting to be input                 */
static int bits_to_go;		/* Number of bits still in buffer           */


/* INITIALIZE BIT INPUT. */

start_inputing_bits()
{   bits_to_go = 0;				/* Buffer starts out with   */
}						/* no bits in it.           */


/* INPUT A BIT. */

int input_bit()
{   int t;
    bits_to_go -= 1;
    if (bits_to_go<0) {				/* Read the next byte if no */
        buffer = getc(stdin);			/* bits are left in the     */
        bits_to_go = 7;				/* buffer. Return anything  */
    }			   			/* after end-of-file.       */
    t = buffer&1;
    buffer >>= 1;				/* Return the next bit from */
    return t;					/* the bottom of the byte.  */
}