From c2decd39a63edb2bab2a21f66471108033236bcf Mon Sep 17 00:00:00 2001
From: Jean-Marc Valin <jean-marc.valin@usherbrooke.ca>
Date: Sat, 22 Mar 2008 22:58:45 +1100
Subject: [PATCH] Made a second version of ec_{en|de}code optimised for
encoding bits (no div required) and using it in ec_{en|de}c_bits()
---
libcelt/entdec.c | 4 ++--
libcelt/entdec.h | 1 +
libcelt/entenc.c | 4 ++--
libcelt/entenc.h | 1 +
libcelt/rangedec.c | 9 +++++++++
libcelt/rangeenc.c | 12 ++++++++++++
6 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/libcelt/entdec.c b/libcelt/entdec.c
index 76b8c904..3b25dd59 100644
--- a/libcelt/entdec.c
+++ b/libcelt/entdec.c
@@ -88,13 +88,13 @@ ec_uint32 ec_dec_bits(ec_dec *_this,int _ftb){
unsigned ft;
t=0;
while(_ftb>EC_UNIT_BITS){
- s=ec_decode(_this,EC_UNIT_MASK+1);
+ s=ec_decode_bin(_this,EC_UNIT_BITS);
ec_dec_update(_this,s,s+1,EC_UNIT_MASK+1);
t=t<<EC_UNIT_BITS|s;
_ftb-=EC_UNIT_BITS;
}
ft=1U<<_ftb;
- s=ec_decode(_this,ft);
+ s=ec_decode_bin(_this,_ftb);
ec_dec_update(_this,s,s+1,ft);
t=t<<_ftb|s;
return t;
diff --git a/libcelt/entdec.h b/libcelt/entdec.h
index 423c574e..f5feb1af 100644
--- a/libcelt/entdec.h
+++ b/libcelt/entdec.h
@@ -42,6 +42,7 @@ void ec_dec_init(ec_dec *_this,ec_byte_buffer *_buf);
up to and including the one encoded is fh, then the returned value
will fall in the range [fl,fh).*/
unsigned ec_decode(ec_dec *_this,unsigned _ft);
+unsigned ec_decode_bin(ec_dec *_this,unsigned bits);
/*Advance the decoder past the next symbol using the frequency information the
symbol was encoded with.
Exactly one call to ec_decode() must have been made so that all necessary
diff --git a/libcelt/entenc.c b/libcelt/entenc.c
index 1ff07604..7859f638 100644
--- a/libcelt/entenc.c
+++ b/libcelt/entenc.c
@@ -70,11 +70,11 @@ void ec_enc_bits(ec_enc *_this,ec_uint32 _fl,int _ftb){
while(_ftb>EC_UNIT_BITS){
_ftb-=EC_UNIT_BITS;
fl=(unsigned)(_fl>>_ftb)&EC_UNIT_MASK;
- ec_encode(_this,fl,fl+1,EC_UNIT_MASK+1);
+ ec_encode_bin(_this,fl,fl+1,EC_UNIT_BITS);
}
ft=1<<_ftb;
fl=(unsigned)_fl&ft-1;
- ec_encode(_this,fl,fl+1,ft);
+ ec_encode_bin(_this,fl,fl+1,_ftb);
}
void ec_enc_bits64(ec_enc *_this,ec_uint64 _fl,int _ftb){
diff --git a/libcelt/entenc.h b/libcelt/entenc.h
index ebaed887..9b3ab6db 100644
--- a/libcelt/entenc.h
+++ b/libcelt/entenc.h
@@ -42,6 +42,7 @@ void ec_enc_init(ec_enc *_this,ec_byte_buffer *_buf);
decoded value will fall.
_ft: The sum of the frequencies of all the symbols*/
void ec_encode(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _ft);
+void ec_encode_bin(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned bits);
/*Encodes a sequence of raw bits in the stream.
_fl: The bits to encode.
_ftb: The number of bits to encode.
diff --git a/libcelt/rangedec.c b/libcelt/rangedec.c
index 072e9c6a..685ee251 100644
--- a/libcelt/rangedec.c
+++ b/libcelt/rangedec.c
@@ -168,6 +168,15 @@ unsigned ec_decode(ec_dec *_this,unsigned _ft){
return _ft-EC_MINI(s+1,_ft);
}
+unsigned ec_decode_bin(ec_dec *_this,unsigned bits){
+ unsigned s;
+ ec_uint32 ft;
+ ft = (ec_uint32)1<<bits;
+ _this->nrm=_this->rng>>bits;
+ s=(unsigned)((_this->dif-1)/_this->nrm);
+ return ft-EC_MINI(s+1,ft);
+}
+
void ec_dec_update(ec_dec *_this,unsigned _fl,unsigned _fh,unsigned _ft){
ec_uint32 s;
s=_this->nrm*(_ft-_fh);
diff --git a/libcelt/rangeenc.c b/libcelt/rangeenc.c
index 7fcd3d1a..177fcb25 100644
--- a/libcelt/rangeenc.c
+++ b/libcelt/rangeenc.c
@@ -92,6 +92,18 @@ void ec_encode(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _ft){
ec_enc_normalize(_this);
}
+void ec_encode_bin(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned bits){
+ ec_uint32 r, ft;
+ r=_this->rng>>bits;
+ ft = (ec_uint32)1<<bits;
+ if(_fl>0){
+ _this->low+=_this->rng-r*(ft-_fl);
+ _this->rng=r*(_fh-_fl);
+ }
+ else _this->rng-=r*(ft-_fh);
+ ec_enc_normalize(_this);
+}
+
long ec_enc_tell(ec_enc *_this,int _b){
ec_uint32 r;
int l;
--
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