text: /* Copyright (c) 2001-2011 Timothy B. Terriberry
  */
  /*
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
     are met:
  
     - Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
  
     - Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.
  
     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
     A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
     LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
  
  #ifdef HAVE_CONFIG_H
  #include "config.h"
  #endif
  
  #include "entcode.h"
  
  
  
  #if !defined(EC_CLZ)
  int ec_ilog(celt_uint32 _v){
    /*On a Pentium M, this branchless version tested as the fastest on
       1,000,000,000 random 32-bit integers, edging out a similar version with
       branches, and a 256-entry LUT version.*/
    int ret;
    int m;
    ret=!!_v;
    m=!!(_v&0xFFFF0000)<<4;
    _v>>=m;
    ret|=m;
    m=!!(_v&0xFF00)<<3;
    _v>>=m;
    ret|=m;
    m=!!(_v&0xF0)<<2;
    _v>>=m;
    ret|=m;
    m=!!(_v&0xC)<<1;
    _v>>=m;
    ret|=m;
    ret+=!!(_v&0x2);
    return ret;
  }
  #endif
  
  
  celt_uint32 ec_tell_frac(ec_ctx *_this){
    celt_uint32 nbits;
    celt_uint32 r;
    int         l;
    int         i;
    /*To handle the non-integral number of bits still left in the encoder/decoder
       state, we compute the worst-case number of bits of val that must be
       encoded to ensure that the value is inside the range for any possible
       subsequent bits.
      The computation here is independent of val itself (the decoder does not
       even track that value), even though the real number of bits used after
       ec_enc_done() may be 1 smaller if rng is a power of two and the
       corresponding trailing bits of val are all zeros.
      If we did try to track that special case, then coding a value with a
       probability of 1/(1<<n) might sometimes appear to use more than n bits.
      This may help explain the surprising result that a newly initialized
       encoder or decoder claims to have used 1 bit.*/
    nbits=_this->nbits_total<<BITRES;
    l=EC_ILOG(_this->rng);
    r=_this->rng>>l-16;
    for(i=BITRES;i-->0;){
      int b;
      r=r*r>>15;
      b=(int)(r>>16);
      l=l<<1|b;
      r>>=b;
    }
    return nbits-l;
  }
  