#ifndef AC_HEADER#define AC_HEADER#include <stdio.h>typedef struct {  FILE *fp;  long low;  long high;  long fbits;  int buffer;  int bits_to_go;  long total_bits;} ac_encoder;typedef struct {  FILE *fp;  long value;  long low;  long high;  int buffer;  int bits_to_go;  int garbage_bits;} ac_decoder;typedef struct {  int nsym;  int *freq;  int *cfreq;  int adapt;} ac_model;void ac_encoder_init (ac_encoder *, const char *);void ac_encoder_done (ac_encoder *);void ac_decoder_init (ac_decoder *, const char *);void ac_decoder_done (ac_decoder *);void ac_model_init (ac_model *, int, int *, int);void ac_model_done (ac_model *);long ac_encoder_bits (ac_encoder *);void ac_encode_symbol (ac_encoder *, ac_model *, int);int ac_decode_symbol (ac_decoder *, ac_model *);#endif