Eliminate the ec_int32 and ec_uint32 typedefs.
[opus.git] / libcelt / entenc.c
index 1ff1036..df649a6 100644 (file)
@@ -1,5 +1,5 @@
-/* (C) 2001-2008 Timothy B. Terriberry
-   (C) 2008 Jean-Marc Valin */
+/* Copyright (c) 2001-2011 Timothy B. Terriberry
+   Copyright (c) 2008-2009 Xiph.Org Foundation */
 /*
    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.
 
-   - Neither the name of the Xiph.org Foundation nor the names of its
-   contributors may be used to endorse or promote products derived from
-   this software without specific prior written permission.
-
    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
-#ifdef HAVE_CONFIG_H
-#include "config.h"
+#if defined(HAVE_CONFIG_H)
+# include "config.h"
 #endif
-
 #include "os_support.h"
-#include "entenc.h"
 #include "arch.h"
+#include "entenc.h"
+#include "mfrngcod.h"
 
 
-#define EC_BUFFER_INCREMENT (256)
 
-void ec_byte_writeinit_buffer(ec_byte_buffer *_b, unsigned char *_buf, long _size){
-  _b->ptr=_b->buf=_buf;
-  _b->end_ptr=_b->buf+_size-1;
-  _b->storage=_size;
-  _b->resizable=0;
-}
+/*A range encoder.
+  See entdec.c and the references for implementation details \cite{Mar79,MNW98}.
+
+  @INPROCEEDINGS{Mar79,
+   author="Martin, G.N.N.",
+   title="Range encoding: an algorithm for removing redundancy from a digitised
+    message",
+   booktitle="Video \& Data Recording Conference",
+   year=1979,
+   address="Southampton",
+   month=Jul
+  }
+  @ARTICLE{MNW98,
+   author="Alistair Moffat and Radford Neal and Ian H. Witten",
+   title="Arithmetic Coding Revisited",
+   journal="{ACM} Transactions on Information Systems",
+   year=1998,
+   volume=16,
+   number=3,
+   pages="256--294",
+   month=Jul,
+   URL="http://www.stanford.edu/class/ee398/handouts/papers/Moffat98ArithmCoding.pdf"
+  }*/
+
+
 
-void ec_byte_writeinit(ec_byte_buffer *_b){
-  _b->ptr=_b->buf=celt_alloc(EC_BUFFER_INCREMENT*sizeof(char));
-  _b->storage=EC_BUFFER_INCREMENT;
-  _b->end_ptr=_b->buf;
-  _b->resizable=1;
+static int ec_write_byte(ec_enc *_this,unsigned _value){
+  if(_this->offs+_this->end_offs>=_this->storage)return -1;
+  _this->buf[_this->offs++]=(unsigned char)_value;
+  return 0;
 }
 
-void ec_byte_writetrunc(ec_byte_buffer *_b,long _bytes){
-  _b->ptr=_b->buf+_bytes;
+static int ec_write_byte_at_end(ec_enc *_this,unsigned _value){
+  if(_this->offs+_this->end_offs>=_this->storage)return -1;
+  _this->buf[_this->storage-++(_this->end_offs)]=(unsigned char)_value;
+  return 0;
 }
 
-void ec_byte_write1(ec_byte_buffer *_b,unsigned _value){
-  ptrdiff_t endbyte;
-  endbyte=_b->ptr-_b->buf;
-  if(endbyte>=_b->storage){
-    if (_b->resizable){
-      _b->buf=celt_realloc(_b->buf,(_b->storage+EC_BUFFER_INCREMENT)*sizeof(char));
-      _b->storage+=EC_BUFFER_INCREMENT;
-      _b->ptr=_b->buf+endbyte;
-    } else {
-      celt_fatal("range encoder overflow\n");
+
+/*Outputs a symbol, with a carry bit.
+  If there is a potential to propagate a carry over several symbols, they are
+   buffered until it can be determined whether or not an actual carry will
+   occur.
+  If the counter for the buffered symbols overflows, then the stream becomes
+   undecodable.
+  This gives a theoretical limit of a few billion symbols in a single packet on
+   32-bit systems.
+  The alternative is to truncate the range in order to force a carry, but
+   requires similar carry tracking in the decoder, needlessly slowing it down.*/
+static void ec_enc_carry_out(ec_enc *_this,int _c){
+  if(_c!=EC_SYM_MAX){
+    /*No further carry propagation possible, flush buffer.*/
+    int carry;
+    carry=_c>>EC_SYM_BITS;
+    /*Don't output a byte on the first write.
+      This compare should be taken care of by branch-prediction thereafter.*/
+    if(_this->rem>=0)_this->error|=ec_write_byte(_this,_this->rem+carry);
+    if(_this->ext>0){
+      unsigned sym;
+      sym=EC_SYM_MAX+carry&EC_SYM_MAX;
+      do _this->error|=ec_write_byte(_this,sym);
+      while(--(_this->ext)>0);
     }
+    _this->rem=_c&EC_SYM_MAX;
   }
-  *(_b->ptr++)=(unsigned char)_value;
+  else _this->ext++;
 }
 
-void ec_byte_write_at_end(ec_byte_buffer *_b,unsigned _value){
-  if (_b->end_ptr < _b->ptr)
-  {
-    celt_fatal("byte buffer collision");
+static void ec_enc_normalize(ec_enc *_this){
+  /*If the range is too small, output some bits and rescale it.*/
+  while(_this->rng<=EC_CODE_BOT){
+    ec_enc_carry_out(_this,(int)(_this->val>>EC_CODE_SHIFT));
+    /*Move the next-to-high-order symbol into the high-order position.*/
+    _this->val=_this->val<<EC_SYM_BITS&EC_CODE_TOP-1;
+    _this->rng<<=EC_SYM_BITS;
+    _this->nbits_total+=EC_SYM_BITS;
   }
-  *(_b->end_ptr--)=(unsigned char)_value;
 }
 
-void ec_byte_write4(ec_byte_buffer *_b,ec_uint32 _value){
-  ptrdiff_t endbyte;
-  endbyte=_b->ptr-_b->buf;
-  if(endbyte+4>_b->storage){
-    if (_b->resizable){
-      _b->buf=celt_realloc(_b->buf,(_b->storage+EC_BUFFER_INCREMENT)*sizeof(char));
-      _b->storage+=EC_BUFFER_INCREMENT;
-      _b->ptr=_b->buf+endbyte;
-    } else {
-      celt_fatal("range encoder overflow\n");
-    }
-  }
-  *(_b->ptr++)=(unsigned char)_value;
-  _value>>=8;
-  *(_b->ptr++)=(unsigned char)_value;
-  _value>>=8;
-  *(_b->ptr++)=(unsigned char)_value;
-  _value>>=8;
-  *(_b->ptr++)=(unsigned char)_value;
+void ec_enc_init(ec_enc *_this,unsigned char *_buf,celt_uint32 _size){
+  _this->buf=_buf;
+  _this->end_offs=0;
+  _this->end_window=0;
+  _this->nend_bits=0;
+  /*This is the offset from which ec_tell() will subtract partial bits.*/
+  _this->nbits_total=EC_CODE_BITS+1;
+  _this->offs=0;
+  _this->rng=EC_CODE_TOP;
+  _this->rem=-1;
+  _this->val=0;
+  _this->ext=0;
+  _this->storage=_size;
+  _this->error=0;
 }
 
-void ec_byte_writecopy(ec_byte_buffer *_b,void *_source,long _bytes){
-  ptrdiff_t endbyte;
-  endbyte=_b->ptr-_b->buf;
-  if(endbyte+_bytes>_b->storage){
-    if (_b->resizable){
-      _b->storage=endbyte+_bytes+EC_BUFFER_INCREMENT;
-      _b->buf=celt_realloc(_b->buf,_b->storage*sizeof(char));
-      _b->ptr=_b->buf+endbyte;
-    } else {
-      celt_fatal("range encoder overflow\n");
-    }
+void ec_encode(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _ft){
+  celt_uint32 r;
+  r=_this->rng/_ft;
+  if(_fl>0){
+    _this->val+=_this->rng-IMUL32(r,(_ft-_fl));
+    _this->rng=IMUL32(r,(_fh-_fl));
   }
-  memmove(_b->ptr,_source,_bytes);
-  _b->ptr+=_bytes;
+  else _this->rng-=IMUL32(r,(_ft-_fh));
+  ec_enc_normalize(_this);
 }
 
-void ec_byte_writeclear(ec_byte_buffer *_b){
-  if (_b->resizable)
-    celt_free(_b->buf);
+void ec_encode_bin(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _bits){
+  celt_uint32 r;
+  r=_this->rng>>_bits;
+  if(_fl>0){
+    _this->val+=_this->rng-IMUL32(r,((1<<_bits)-_fl));
+    _this->rng=IMUL32(r,(_fh-_fl));
+  }
+  else _this->rng-=IMUL32(r,((1<<_bits)-_fh));
+  ec_enc_normalize(_this);
 }
 
+/*The probability of having a "one" is 1/(1<<_logp).*/
+void ec_enc_bit_logp(ec_enc *_this,int _val,unsigned _logp){
+  celt_uint32 r;
+  celt_uint32 s;
+  celt_uint32 l;
+  r=_this->rng;
+  l=_this->val;
+  s=r>>_logp;
+  r-=s;
+  if(_val)_this->val=l+r;
+  _this->rng=_val?s:r;
+  ec_enc_normalize(_this);
+}
 
-
-void ec_enc_bits(ec_enc *_this,ec_uint32 _fl,int _ftb){
-  unsigned fl;
-  unsigned ft;
-  while(_ftb>EC_UNIT_BITS){
-    _ftb-=EC_UNIT_BITS;
-    fl=(unsigned)(_fl>>_ftb)&EC_UNIT_MASK;
-    ec_encode_raw(_this,fl,fl+1,EC_UNIT_BITS);
+void ec_enc_icdf(ec_enc *_this,int _s,const unsigned char *_icdf,unsigned _ftb){
+  celt_uint32 r;
+  r=_this->rng>>_ftb;
+  if(_s>0){
+    _this->val+=_this->rng-IMUL32(r,_icdf[_s-1]);
+    _this->rng=IMUL32(r,_icdf[_s-1]-_icdf[_s]);
   }
-  ft=1<<_ftb;
-  fl=(unsigned)_fl&ft-1;
-  ec_encode_raw(_this,fl,fl+1,_ftb);
+  else _this->rng-=IMUL32(r,_icdf[_s]);
+  ec_enc_normalize(_this);
 }
 
-void ec_enc_uint(ec_enc *_this,ec_uint32 _fl,ec_uint32 _ft){
+void ec_enc_uint(ec_enc *_this,celt_uint32 _fl,celt_uint32 _ft){
   unsigned  ft;
   unsigned  fl;
   int       ftb;
@@ -146,14 +185,114 @@ void ec_enc_uint(ec_enc *_this,ec_uint32 _fl,ec_uint32 _ft){
   celt_assert(_ft>1);
   _ft--;
   ftb=EC_ILOG(_ft);
-  if(ftb>EC_UNIT_BITS){
-    ftb-=EC_UNIT_BITS;
+  if(ftb>EC_UINT_BITS){
+    ftb-=EC_UINT_BITS;
     ft=(_ft>>ftb)+1;
     fl=(unsigned)(_fl>>ftb);
     ec_encode(_this,fl,fl+1,ft);
-    ec_enc_bits(_this,_fl,ftb);
-  } else {
-    ec_encode(_this,_fl,_fl+1,_ft+1);
+    ec_enc_bits(_this,_fl&((celt_uint32)1<<ftb)-1,ftb);
   }
+  else ec_encode(_this,_fl,_fl+1,_ft+1);
 }
 
+void ec_enc_bits(ec_enc *_this,celt_uint32 _fl,unsigned _bits){
+  ec_window window;
+  int       used;
+  window=_this->end_window;
+  used=_this->nend_bits;
+  if(used+_bits>EC_WINDOW_SIZE){
+    do{
+      _this->error|=ec_write_byte_at_end(_this,(unsigned)window&EC_SYM_MAX);
+      window>>=EC_SYM_BITS;
+      used-=EC_SYM_BITS;
+    }
+    while(used>=EC_SYM_BITS);
+  }
+  window|=(ec_window)_fl<<used;
+  used+=_bits;
+  _this->end_window=window;
+  _this->nend_bits=used;
+  _this->nbits_total+=_bits;
+}
+
+void ec_enc_patch_initial_bits(ec_enc *_this,unsigned _val,unsigned _nbits){
+  int      shift;
+  unsigned mask;
+  celt_assert(_nbits<=EC_SYM_BITS);
+  shift=EC_SYM_BITS-_nbits;
+  mask=(1<<_nbits)-1<<shift;
+  if(_this->offs>0){
+    /*The first byte has been finalized.*/
+    _this->buf[0]=(unsigned char)(_this->buf[0]&~mask|_val<<shift);
+  }
+  else if(_this->rem>=0){
+    /*The first byte is still awaiting carry propagation.*/
+    _this->rem=_this->rem&~mask|_val<<shift;
+  }
+  else if(_this->rng<=EC_CODE_TOP>>shift){
+    /*The renormalization loop has never been run.*/
+    _this->val=_this->val&~((celt_uint32)mask<<EC_CODE_SHIFT)|
+     (celt_uint32)_val<<EC_CODE_SHIFT+shift;
+  }
+  /*The encoder hasn't even encoded _nbits of data yet.*/
+  else _this->error=-1;
+}
+
+void ec_enc_shrink(ec_enc *_this,celt_uint32 _size){
+  celt_assert(_this->offs+_this->end_offs<=_size);
+  CELT_MOVE(_this->buf+_size-_this->end_offs,
+   _this->buf+_this->storage-_this->end_offs,_this->end_offs);
+  _this->storage=_size;
+}
+
+void ec_enc_done(ec_enc *_this){
+  ec_window   window;
+  int         used;
+  celt_uint32 msk;
+  celt_uint32 end;
+  int         l;
+  /*We output the minimum number of bits that ensures that the symbols encoded
+     thus far will be decoded correctly regardless of the bits that follow.*/
+  l=EC_CODE_BITS-EC_ILOG(_this->rng);
+  msk=EC_CODE_TOP-1>>l;
+  end=_this->val+msk&~msk;
+  if((end|msk)>=_this->val+_this->rng){
+    l++;
+    msk>>=1;
+    end=_this->val+msk&~msk;
+  }
+  while(l>0){
+    ec_enc_carry_out(_this,(int)(end>>EC_CODE_SHIFT));
+    end=end<<EC_SYM_BITS&EC_CODE_TOP-1;
+    l-=EC_SYM_BITS;
+  }
+  /*If we have a buffered byte flush it into the output buffer.*/
+  if(_this->rem>=0||_this->ext>0)ec_enc_carry_out(_this,0);
+  /*If we have buffered extra bits, flush them as well.*/
+  window=_this->end_window;
+  used=_this->nend_bits;
+  while(used>=EC_SYM_BITS){
+    _this->error|=ec_write_byte_at_end(_this,(unsigned)window&EC_SYM_MAX);
+    window>>=EC_SYM_BITS;
+    used-=EC_SYM_BITS;
+  }
+  /*Clear any excess space and add any remaining extra bits to the last byte.*/
+  if(!_this->error){
+    CELT_MEMSET(_this->buf+_this->offs,0,
+     _this->storage-_this->offs-_this->end_offs);
+    if(used>0){
+      /*If there's no range coder data at all, give up.*/
+      if(_this->end_offs>=_this->storage)_this->error=-1;
+      else{
+        l=-l;
+        /*If we've busted, don't add too many extra bits to the last byte; it
+           would corrupt the range coder data, and that's more important.*/
+        if(_this->offs+_this->end_offs>=_this->storage&&l<used){
+          window&=(1<<l)-1;
+          _this->error=-1;
+        }
+      }
+      _this->buf[_this->storage-_this->end_offs-1]|=(unsigned char)window;
+    }
+  }
+}