#include?
#include?

#include?“ac.h“

#define?Code_value_bits?16

#define?Top_value?（（（long）1<#define?First_qtr?（Top_value/4+1）
#define?Half	??（2*First_qtr）
#define?Third_qtr?（3*First_qtr）
#define?Max_frequency?16383

static?void?output_bit?（ac_encoder?*?int）;
static?void?bit_plus_follow?（ac_encoder?*?int）;
static?int?input_bit?（ac_decoder?*）;
static?void?update_model?（ac_model?*?int）;

#define?error（m）???????????????????????????????????????????\
do??{??????????????????????????????????????????????????????\
??fflush?（stdout）;?????????????????????????????????????????\
??fprintf?（stderr?“%s:%d:?error:?“?__FILE__?__LINE__）;??\
??fprintf?（stderr?m）;?????????????????????????????????????\
??fprintf?（stderr?“\n“）;??????????????????????????????????\
??exit?（1）;????????????????????????????????????????????????\
}??while?（0）

#define?check（bm）?????????????????????????????????????????\
do??{??????????????????????????????????????????????????????\
??if?（b）???????????????????????????????????????????????????\
????error?（m）;?????????????????????????????????????????????\
}??while?（0）

static?void
output_bit?（ac_encoder?*ace?int?bit）
{
??ace->buffer?>>=?1;
??if?（bit）
????ace->buffer?|=?0x80;
??ace->bits_to_go?-=?1;
??ace->total_bits?+=?1;
??if?（ace->bits_to_go==0）??{
????if?（ace->fp）
??????putc?（ace->buffer?ace->fp）;
????ace->bits_to_go?=?8;
??}

??return;
}

static?void
bit_plus_follow?（ac_encoder?*ace?int?bit）
{
??output_bit?（ace?bit）;
??while?（ace->fbits?>?0）??{
????output_bit?（ace?!bit）;
????ace->fbits?-=?1;
??}

??return;
}

static?int
input_bit?（ac_decoder?*acd）
{
??int?t;

??if?（acd->bits_to_go==0）??{
????acd->buffer?=?getc（acd->fp）;
????if?（acd->buffer==EOF）??{
??????acd->garbage_bits?+=?1;
??????if?（acd->garbage_bits>Code_value_bits-2）
????????error?（“arithmetic?decoder?bad?input?file“）;
????}
????acd->bits_to_go?=?8;
??}

??t?=?acd->buffer&1;
??acd->buffer?>>=?1;
??acd->bits_to_go?-=?1;

??return?t;
}

static?void
update_model?（ac_model?*acm?int?sym）
{
??int?i;

??if?（acm->cfreq[0]==Max_frequency）??{
????int?cum?=?0;
????acm->cfreq[acm->nsym]?=?0;
????for?（i?=?acm->nsym-1;?i>=0;?i--）??{
??????acm->freq[i]?=?（acm->freq[i]?+?1）?/?2;
??????cum?+=?acm->freq[i];
??????acm->cfreq[i]?=?cum;
????}
??}

??acm->freq[sym]?+=?1;
??for?（i=sym;?i>=0;?i--）
????acm->cfreq[i]?+=?1;

??return;
}

void
ac_encoder_init?（ac_encoder?*ace?const?char?*fn）
{

??if?（fn）??{
????ace->fp?=?fopen?（fn?“wb“）;?/*?open?in?binary?mode?*/
????check?（!ace->fp?“arithmetic?encoder?could?not?open?file“）;
??}??else??{
????ace->fp?=?NULL;
??}

??ace->bits_to_go?=?8;

??ace->low?=?0;
??ace->high?=?Top_value;
??ace->fbits?=?0;
??ace->buffer?=?0;

??ace->total_bits?=?0;

??return;
}

void
ac_encoder_done?（ac_encoder?*ace）
{
??ace->fbits?+=?1;
??if?（ace->low?????bit_plus_follow?（ace?0）;
??else
????bit_plus_follow?（ace?1）;
??if?（ace->fp）
????putc?（ace->buffer?>>?ace->bits_to_go?ace->fp）;

??if?（ace->fp）
????fclose?（ace->fp）;

??r

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件???????2528??2007-03-18?21:34??Adaptive?arithmetic?code\acdemo.c

?????文件???????2615??2007-03-18?21:34??Adaptive?arithmetic?code\ac.txt

?????文件????????816??2007-03-18?21:34??Adaptive?arithmetic?code\ac.h

?????文件???????6306??2007-03-18?21:34??Adaptive?arithmetic?code\ac.c

?????目錄??????????0??2007-03-18?21:35??Adaptive?arithmetic?code

-----------?---------??----------?-----??----

????????????????12265????????????????????5