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Add ec_dec_tell() to report the same information as ec_enc_tell() decode side. Remove ec_enc_tell() and replace it with ec_enc_tellf(): just request 0 fractional bits if you want an integer value.

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git-svn-id: http://svn.xiph.org/trunk/ghost@14394 0101bb08-14d6-0310-b084-bc0e0c8e3800
This commit is contained in:
tterribe 2008-01-11 05:51:49 +00:00 • committed by Jean-Marc Valin
parent fad779ca56
commit 3eff11d8d4
7 changed files with 111 additions and 75 deletions
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55
libentcode/rangedec.c
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@ -120,26 +120,24 @@ static int ec_dec_in(ec_dec *_this){
int ret;
ret=ec_byte_read1(_this->buf);
if(ret<0){
unsigned char *buf;
long bytes;
long bytes;
bytes=ec_byte_bytes(_this->buf);
buf=ec_byte_get_buffer(_this->buf);
/*Breaking abstraction: don't do this at home, kids.*/
if(_this->buf->storage==bytes){
ec_byte_adv1(_this->buf);
if(bytes>0){
unsigned char *p;
p=buf+bytes;
/*If we end in a string of 0 or more EC_FOF_RSV1 bytes preceded by a
zero, return an extra EC_FOF_RSV1 byte.*/
do p--;
while(p>buf&&p[0]==EC_FOF_RSV1);
if(!p[0])return EC_FOF_RSV1;
}
if(_this->buf->storage==bytes&&bytes>0){
unsigned char *buf;
buf=ec_byte_get_buffer(_this->buf);
/*If we end in a string of 0 or more EC_FOF_RSV1 bytes preceded by a
zero, return an extra EC_FOF_RSV1 byte.*/
do bytes--;
while(bytes>0&&buf[bytes]==EC_FOF_RSV1);
if(!buf[bytes])ret=EC_FOF_RSV1;
}
return 0;
else ret=0;
/*Needed to make sure the above conditional only triggers once, and to keep
oc_dec_tell() operating correctly.*/
ec_byte_adv1(_this->buf);
}
else return ret;
return ret;
}
/*Normalizes the contents of dif and rng so that rng lies entirely in the
@ -188,6 +186,31 @@ void ec_dec_update(ec_dec *_this,unsigned _fl,unsigned _fh,unsigned _ft){
ec_dec_normalize(_this);
}
long ec_dec_tell(ec_dec *_this,int _b){
ec_uint32 r;
int l;
long nbits;
nbits=ec_byte_bytes(_this->buf)-(EC_CODE_BITS+EC_SYM_BITS-1)/EC_SYM_BITS<<3;
/*To handle the non-integral number of bits still left in the encoder state,
we compute the number of bits of low that must be encoded to ensure that
the value is inside the range for any possible subsequent bits.
Note that this is subtly different than the actual value we would end the
stream with, which tries to make as many of the trailing bits zeros as
possible.*/
nbits+=EC_CODE_BITS;
nbits<<=_b;
l=EC_ILOG(_this->rng);
r=_this->rng>>l-16;
while(_b-->0){
int b;
r=r*r>>15;
b=(int)(r>>16);
l=l<<1|b;
r>>=b;
}
return nbits-l;
}
#if 0
int ec_dec_done(ec_dec *_this){
unsigned low;