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-rw-r--r--media/libopus/celt/entcode.c153
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+/* 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 COPYRIGHT OWNER
+ 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"
+#include "arch.h"
+
+#if !defined(EC_CLZ)
+/*This is a fallback for systems where we don't know how to access
+ a BSR or CLZ instruction (see ecintrin.h).
+ If you are optimizing Opus on a new platform and it has a native CLZ or
+ BZR (e.g. cell, MIPS, x86, etc) then making it available to Opus will be
+ an easy performance win.*/
+int ec_ilog(opus_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
+
+#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