Update to opus-HEAD-66611f1.

celt/entcode.c

 /* 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.
 
@@ skipping 44 matching lines @@
   _v>>=m;
   ret|=m;
   m=!!(_v&0xC)<<1;
   _v>>=m;
   ret|=m;
   ret+=!!(_v&0x2);
   return ret;
 }
 #endif
 
+#if 1
+/* This is a faster version of ec_tell_frac() that takes advantage
+   of the low (1/8 bit) resolution to use just a linear function
+   followed by a lookup to determine the exact transition thresholds. */
+opus_uint32 ec_tell_frac(ec_ctx *_this){
+  static const unsigned correction[8] =
+    {35733, 38967, 42495, 46340,
+     50535, 55109, 60097, 65535};
+  opus_uint32 nbits;
+  opus_uint32 r;
+  int         l;
+  unsigned    b;
+  nbits=_this->nbits_total<<BITRES;
+  l=EC_ILOG(_this->rng);
+  r=_this->rng>>(l-16);
+  b = (r>>12)-8;
+  b += r>correction[b];
+  l = (l<<3)+b;
+  return nbits-l;
+}
+#else
 opus_uint32 ec_tell_frac(ec_ctx *_this){
   opus_uint32 nbits;
   opus_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;
 }
+#endif
+
+#ifdef USE_SMALL_DIV_TABLE
+/* Result of 2^32/(2*i+1), except for i=0. */
+const opus_uint32 SMALL_DIV_TABLE[129] = {
+   0xFFFFFFFF, 0x55555555, 0x33333333, 0x24924924,
+   0x1C71C71C, 0x1745D174, 0x13B13B13, 0x11111111,
+   0x0F0F0F0F, 0x0D79435E, 0x0C30C30C, 0x0B21642C,
+   0x0A3D70A3, 0x097B425E, 0x08D3DCB0, 0x08421084,
+   0x07C1F07C, 0x07507507, 0x06EB3E45, 0x06906906,
+   0x063E7063, 0x05F417D0, 0x05B05B05, 0x0572620A,
+   0x05397829, 0x05050505, 0x04D4873E, 0x04A7904A,
+   0x047DC11F, 0x0456C797, 0x04325C53, 0x04104104,
+   0x03F03F03, 0x03D22635, 0x03B5CC0E, 0x039B0AD1,
+   0x0381C0E0, 0x0369D036, 0x03531DEC, 0x033D91D2,
+   0x0329161F, 0x03159721, 0x03030303, 0x02F14990,
+   0x02E05C0B, 0x02D02D02, 0x02C0B02C, 0x02B1DA46,
+   0x02A3A0FD, 0x0295FAD4, 0x0288DF0C, 0x027C4597,
+   0x02702702, 0x02647C69, 0x02593F69, 0x024E6A17,
+   0x0243F6F0, 0x0239E0D5, 0x02302302, 0x0226B902,
+   0x021D9EAD, 0x0214D021, 0x020C49BA, 0x02040810,
+   0x01FC07F0, 0x01F44659, 0x01ECC07B, 0x01E573AC,
+   0x01DE5D6E, 0x01D77B65, 0x01D0CB58, 0x01CA4B30,
+   0x01C3F8F0, 0x01BDD2B8, 0x01B7D6C3, 0x01B20364,
+   0x01AC5701, 0x01A6D01A, 0x01A16D3F, 0x019C2D14,
+   0x01970E4F, 0x01920FB4, 0x018D3018, 0x01886E5F,
+   0x0183C977, 0x017F405F, 0x017AD220, 0x01767DCE,
+   0x01724287, 0x016E1F76, 0x016A13CD, 0x01661EC6,
+   0x01623FA7, 0x015E75BB, 0x015AC056, 0x01571ED3,
+   0x01539094, 0x01501501, 0x014CAB88, 0x0149539E,
+   0x01460CBC, 0x0142D662, 0x013FB013, 0x013C995A,
+   0x013991C2, 0x013698DF, 0x0133AE45, 0x0130D190,
+   0x012E025C, 0x012B404A, 0x01288B01, 0x0125E227,
+   0x01234567, 0x0120B470, 0x011E2EF3, 0x011BB4A4,
+   0x01194538, 0x0116E068, 0x011485F0, 0x0112358E,
+   0x010FEF01, 0x010DB20A, 0x010B7E6E, 0x010953F3,
+   0x01073260, 0x0105197F, 0x0103091B, 0x01010101
+};
+#endif