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< li class = "navelem" > < a class = "el" href = "../../dir_39dc0668bd5a501998f94e8b4e546c71.html" > media< / a > < / li > < li class = "navelem" > < a class = "el" href = "../../dir_c6ada2450b25ab5438a4dba6c9b890af.html" > base< / a > < / li > < / ul >
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< div class = "title" > bit_reader.cc< / div > < / div >
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< div class = "fragment" > < div class = "line" > < a name = "l00001" > < / a > < span class = "lineno" > 1< / span >   < span class = "comment" > // Copyright (c) 2012 The Chromium Authors. All rights reserved.< / span > < / div >
< div class = "line" > < a name = "l00002" > < / a > < span class = "lineno" > 2< / span >   < span class = "comment" > // Use of this source code is governed by a BSD-style license that can be< / span > < / div >
< div class = "line" > < a name = "l00003" > < / a > < span class = "lineno" > 3< / span >   < span class = "comment" > // found in the LICENSE file.< / span > < / div >
< div class = "line" > < a name = "l00004" > < / a > < span class = "lineno" > 4< / span >   < / div >
< div class = "line" > < a name = "l00005" > < / a > < span class = "lineno" > 5< / span >   < span class = "preprocessor" > #include " packager/media/base/bit_reader.h" < / span > < / div >
< div class = "line" > < a name = "l00006" > < / a > < span class = "lineno" > 6< / span >   < / div >
< div class = "line" > < a name = "l00007" > < / a > < span class = "lineno" > 7< / span >   < span class = "preprocessor" > #include < algorithm> < / span > < / div >
< div class = "line" > < a name = "l00008" > < / a > < span class = "lineno" > 8< / span >   < / div >
< div class = "line" > < a name = "l00009" > < / a > < span class = "lineno" > 9< / span >   < span class = "keyword" > namespace < / span > edash_packager {< / div >
< div class = "line" > < a name = "l00010" > < / a > < span class = "lineno" > 10< / span >   < span class = "keyword" > namespace < / span > media {< / div >
< div class = "line" > < a name = "l00011" > < / a > < span class = "lineno" > 11< / span >   < / div >
< div class = "line" > < a name = "l00012" > < / a > < span class = "lineno" > < a class = "line" href = "../../df/db4/classedash__packager_1_1media_1_1BitReader.html#a7cfecfaf6169a0c9286d62b24e7b934e" > 12< / a > < / span >   < a class = "code" href = "../../df/db4/classedash__packager_1_1media_1_1BitReader.html#a7cfecfaf6169a0c9286d62b24e7b934e" > BitReader::BitReader< / a > (< span class = "keyword" > const< / span > uint8_t* data, off_t size)< / div >
< div class = "line" > < a name = "l00013" > < / a > < span class = "lineno" > 13< / span >   : data_(data), bytes_left_(size), num_remaining_bits_in_curr_byte_(0) {< / div >
< div class = "line" > < a name = "l00014" > < / a > < span class = "lineno" > 14< / span >   DCHECK(data_ != NULL & & bytes_left_ > 0);< / div >
< div class = "line" > < a name = "l00015" > < / a > < span class = "lineno" > 15< / span >   < / div >
< div class = "line" > < a name = "l00016" > < / a > < span class = "lineno" > 16< / span >   UpdateCurrByte();< / div >
< div class = "line" > < a name = "l00017" > < / a > < span class = "lineno" > 17< / span >   }< / div >
< div class = "line" > < a name = "l00018" > < / a > < span class = "lineno" > 18< / span >   < / div >
< div class = "line" > < a name = "l00019" > < / a > < span class = "lineno" > 19< / span >   BitReader::~BitReader() {}< / div >
< div class = "line" > < a name = "l00020" > < / a > < span class = "lineno" > 20< / span >   < / div >
< div class = "line" > < a name = "l00021" > < / a > < span class = "lineno" > < a class = "line" href = "../../df/db4/classedash__packager_1_1media_1_1BitReader.html#acacb97d71aaae01796b90d27e7cdca0a" > 21< / a > < / span >   < span class = "keywordtype" > bool< / span > < a class = "code" href = "../../df/db4/classedash__packager_1_1media_1_1BitReader.html#acacb97d71aaae01796b90d27e7cdca0a" > BitReader::SkipBits< / a > (< span class = "keywordtype" > int< / span > num_bits) {< / div >
< div class = "line" > < a name = "l00022" > < / a > < span class = "lineno" > 22< / span >   DCHECK_GE(num_bits, 0);< / div >
< div class = "line" > < a name = "l00023" > < / a > < span class = "lineno" > 23< / span >   < / div >
< div class = "line" > < a name = "l00024" > < / a > < span class = "lineno" > 24< / span >   < span class = "comment" > // Skip any bits in the current byte waiting to be processed, then< / span > < / div >
< div class = "line" > < a name = "l00025" > < / a > < span class = "lineno" > 25< / span >   < span class = "comment" > // process full bytes until less than 8 bits remaining.< / span > < / div >
< div class = "line" > < a name = "l00026" > < / a > < span class = "lineno" > 26< / span >   < span class = "keywordflow" > if< / span > (num_bits > num_remaining_bits_in_curr_byte_) {< / div >
< div class = "line" > < a name = "l00027" > < / a > < span class = "lineno" > 27< / span >   num_bits -= num_remaining_bits_in_curr_byte_;< / div >
< div class = "line" > < a name = "l00028" > < / a > < span class = "lineno" > 28< / span >   num_remaining_bits_in_curr_byte_ = 0;< / div >
< div class = "line" > < a name = "l00029" > < / a > < span class = "lineno" > 29< / span >   < / div >
< div class = "line" > < a name = "l00030" > < / a > < span class = "lineno" > 30< / span >   < span class = "keywordtype" > int< / span > num_bytes = num_bits / 8;< / div >
< div class = "line" > < a name = "l00031" > < / a > < span class = "lineno" > 31< / span >   num_bits %= 8;< / div >
< div class = "line" > < a name = "l00032" > < / a > < span class = "lineno" > 32< / span >   < span class = "keywordflow" > if< / span > (bytes_left_ < num_bytes) {< / div >
< div class = "line" > < a name = "l00033" > < / a > < span class = "lineno" > 33< / span >   bytes_left_ = 0;< / div >
< div class = "line" > < a name = "l00034" > < / a > < span class = "lineno" > 34< / span >   < span class = "keywordflow" > return< / span > < span class = "keyword" > false< / span > ;< / div >
< div class = "line" > < a name = "l00035" > < / a > < span class = "lineno" > 35< / span >   }< / div >
< div class = "line" > < a name = "l00036" > < / a > < span class = "lineno" > 36< / span >   bytes_left_ -= num_bytes;< / div >
< div class = "line" > < a name = "l00037" > < / a > < span class = "lineno" > 37< / span >   data_ += num_bytes;< / div >
< div class = "line" > < a name = "l00038" > < / a > < span class = "lineno" > 38< / span >   UpdateCurrByte();< / div >
< div class = "line" > < a name = "l00039" > < / a > < span class = "lineno" > 39< / span >   < / div >
< div class = "line" > < a name = "l00040" > < / a > < span class = "lineno" > 40< / span >   < span class = "comment" > // If there is no more data remaining, only return true if we< / span > < / div >
< div class = "line" > < a name = "l00041" > < / a > < span class = "lineno" > 41< / span >   < span class = "comment" > // skipped all that were requested.< / span > < / div >
< div class = "line" > < a name = "l00042" > < / a > < span class = "lineno" > 42< / span >   < span class = "keywordflow" > if< / span > (num_remaining_bits_in_curr_byte_ == 0)< / div >
< div class = "line" > < a name = "l00043" > < / a > < span class = "lineno" > 43< / span >   < span class = "keywordflow" > return< / span > (num_bits == 0);< / div >
< div class = "line" > < a name = "l00044" > < / a > < span class = "lineno" > 44< / span >   }< / div >
< div class = "line" > < a name = "l00045" > < / a > < span class = "lineno" > 45< / span >   < / div >
< div class = "line" > < a name = "l00046" > < / a > < span class = "lineno" > 46< / span >   < span class = "comment" > // Less than 8 bits remaining to skip. Use ReadBitsInternal to verify< / span > < / div >
< div class = "line" > < a name = "l00047" > < / a > < span class = "lineno" > 47< / span >   < span class = "comment" > // that the remaining bits we need exist, and adjust them as necessary< / span > < / div >
< div class = "line" > < a name = "l00048" > < / a > < span class = "lineno" > 48< / span >   < span class = "comment" > // for subsequent operations.< / span > < / div >
< div class = "line" > < a name = "l00049" > < / a > < span class = "lineno" > 49< / span >   uint64_t not_needed;< / div >
< div class = "line" > < a name = "l00050" > < / a > < span class = "lineno" > 50< / span >   < span class = "keywordflow" > return< / span > ReadBitsInternal(num_bits, & not_needed);< / div >
< div class = "line" > < a name = "l00051" > < / a > < span class = "lineno" > 51< / span >   }< / div >
< div class = "line" > < a name = "l00052" > < / a > < span class = "lineno" > 52< / span >   < / div >
< div class = "line" > < a name = "l00053" > < / a > < span class = "lineno" > < a class = "line" href = "../../df/db4/classedash__packager_1_1media_1_1BitReader.html#a1409a0968749ca5a55ba823cd718065b" > 53< / a > < / span >   < span class = "keywordtype" > int< / span > < a class = "code" href = "../../df/db4/classedash__packager_1_1media_1_1BitReader.html#a1409a0968749ca5a55ba823cd718065b" > BitReader::bits_available< / a > ()< span class = "keyword" > const < / span > {< / div >
< div class = "line" > < a name = "l00054" > < / a > < span class = "lineno" > 54< / span >   < span class = "keywordflow" > return< / span > 8 * bytes_left_ + num_remaining_bits_in_curr_byte_;< / div >
< div class = "line" > < a name = "l00055" > < / a > < span class = "lineno" > 55< / span >   }< / div >
< div class = "line" > < a name = "l00056" > < / a > < span class = "lineno" > 56< / span >   < / div >
< div class = "line" > < a name = "l00057" > < / a > < span class = "lineno" > 57< / span >   < span class = "keywordtype" > bool< / span > BitReader::ReadBitsInternal(< span class = "keywordtype" > int< / span > num_bits, uint64_t* out) {< / div >
< div class = "line" > < a name = "l00058" > < / a > < span class = "lineno" > 58< / span >   DCHECK_LE(num_bits, 64);< / div >
< div class = "line" > < a name = "l00059" > < / a > < span class = "lineno" > 59< / span >   < / div >
< div class = "line" > < a name = "l00060" > < / a > < span class = "lineno" > 60< / span >   *out = 0;< / div >
< div class = "line" > < a name = "l00061" > < / a > < span class = "lineno" > 61< / span >   < / div >
< div class = "line" > < a name = "l00062" > < / a > < span class = "lineno" > 62< / span >   < span class = "keywordflow" > while< / span > (num_remaining_bits_in_curr_byte_ != 0 & & num_bits != 0) {< / div >
< div class = "line" > < a name = "l00063" > < / a > < span class = "lineno" > 63< / span >   < span class = "keywordtype" > int< / span > bits_to_take = std::min(num_remaining_bits_in_curr_byte_, num_bits);< / div >
< div class = "line" > < a name = "l00064" > < / a > < span class = "lineno" > 64< / span >   < / div >
< div class = "line" > < a name = "l00065" > < / a > < span class = "lineno" > 65< / span >   *out < < = bits_to_take;< / div >
< div class = "line" > < a name = "l00066" > < / a > < span class = "lineno" > 66< / span >   *out += curr_byte_ > > (num_remaining_bits_in_curr_byte_ - bits_to_take);< / div >
< div class = "line" > < a name = "l00067" > < / a > < span class = "lineno" > 67< / span >   num_bits -= bits_to_take;< / div >
< div class = "line" > < a name = "l00068" > < / a > < span class = "lineno" > 68< / span >   num_remaining_bits_in_curr_byte_ -= bits_to_take;< / div >
< div class = "line" > < a name = "l00069" > < / a > < span class = "lineno" > 69< / span >   curr_byte_ & = (1 < < num_remaining_bits_in_curr_byte_) - 1;< / div >
< div class = "line" > < a name = "l00070" > < / a > < span class = "lineno" > 70< / span >   < / div >
< div class = "line" > < a name = "l00071" > < / a > < span class = "lineno" > 71< / span >   < span class = "keywordflow" > if< / span > (num_remaining_bits_in_curr_byte_ == 0)< / div >
< div class = "line" > < a name = "l00072" > < / a > < span class = "lineno" > 72< / span >   UpdateCurrByte();< / div >
< div class = "line" > < a name = "l00073" > < / a > < span class = "lineno" > 73< / span >   }< / div >
< div class = "line" > < a name = "l00074" > < / a > < span class = "lineno" > 74< / span >   < / div >
< div class = "line" > < a name = "l00075" > < / a > < span class = "lineno" > 75< / span >   < span class = "keywordflow" > return< / span > num_bits == 0;< / div >
< div class = "line" > < a name = "l00076" > < / a > < span class = "lineno" > 76< / span >   }< / div >
< div class = "line" > < a name = "l00077" > < / a > < span class = "lineno" > 77< / span >   < / div >
< div class = "line" > < a name = "l00078" > < / a > < span class = "lineno" > 78< / span >   < span class = "keywordtype" > void< / span > BitReader::UpdateCurrByte() {< / div >
< div class = "line" > < a name = "l00079" > < / a > < span class = "lineno" > 79< / span >   DCHECK_EQ(num_remaining_bits_in_curr_byte_, 0);< / div >
< div class = "line" > < a name = "l00080" > < / a > < span class = "lineno" > 80< / span >   < / div >
< div class = "line" > < a name = "l00081" > < / a > < span class = "lineno" > 81< / span >   < span class = "keywordflow" > if< / span > (bytes_left_ == 0)< / div >
< div class = "line" > < a name = "l00082" > < / a > < span class = "lineno" > 82< / span >   < span class = "keywordflow" > return< / span > ;< / div >
< div class = "line" > < a name = "l00083" > < / a > < span class = "lineno" > 83< / span >   < / div >
< div class = "line" > < a name = "l00084" > < / a > < span class = "lineno" > 84< / span >   < span class = "comment" > // Load a new byte and advance pointers.< / span > < / div >
< div class = "line" > < a name = "l00085" > < / a > < span class = "lineno" > 85< / span >   curr_byte_ = *data_;< / div >
< div class = "line" > < a name = "l00086" > < / a > < span class = "lineno" > 86< / span >   ++data_;< / div >
< div class = "line" > < a name = "l00087" > < / a > < span class = "lineno" > 87< / span >   --bytes_left_;< / div >
< div class = "line" > < a name = "l00088" > < / a > < span class = "lineno" > 88< / span >   num_remaining_bits_in_curr_byte_ = 8;< / div >
< div class = "line" > < a name = "l00089" > < / a > < span class = "lineno" > 89< / span >   }< / div >
< div class = "line" > < a name = "l00090" > < / a > < span class = "lineno" > 90< / span >   < / div >
< div class = "line" > < a name = "l00091" > < / a > < span class = "lineno" > 91< / span >   } < span class = "comment" > // namespace media< / span > < / div >
< div class = "line" > < a name = "l00092" > < / a > < span class = "lineno" > 92< / span >   } < span class = "comment" > // namespace edash_packager< / span > < / div >
< div class = "ttc" id = "classedash__packager_1_1media_1_1BitReader_html_a7cfecfaf6169a0c9286d62b24e7b934e" > < div class = "ttname" > < a href = "../../df/db4/classedash__packager_1_1media_1_1BitReader.html#a7cfecfaf6169a0c9286d62b24e7b934e" > edash_packager::media::BitReader::BitReader< / a > < / div > < div class = "ttdeci" > BitReader(const uint8_t *data, off_t size)< / div > < div class = "ttdef" > < b > Definition:< / b > < a href = "../../d5/de0/bit__reader_8cc_source.html#l00012" > bit_reader.cc:12< / a > < / div > < / div >
< div class = "ttc" id = "classedash__packager_1_1media_1_1BitReader_html_a1409a0968749ca5a55ba823cd718065b" > < div class = "ttname" > < a href = "../../df/db4/classedash__packager_1_1media_1_1BitReader.html#a1409a0968749ca5a55ba823cd718065b" > edash_packager::media::BitReader::bits_available< / a > < / div > < div class = "ttdeci" > int bits_available() const < / div > < div class = "ttdef" > < b > Definition:< / b > < a href = "../../d5/de0/bit__reader_8cc_source.html#l00053" > bit_reader.cc:53< / a > < / div > < / div >
< div class = "ttc" id = "classedash__packager_1_1media_1_1BitReader_html_acacb97d71aaae01796b90d27e7cdca0a" > < div class = "ttname" > < a href = "../../df/db4/classedash__packager_1_1media_1_1BitReader.html#acacb97d71aaae01796b90d27e7cdca0a" > edash_packager::media::BitReader::SkipBits< / a > < / div > < div class = "ttdeci" > bool SkipBits(int num_bits)< / div > < div class = "ttdef" > < b > Definition:< / b > < a href = "../../d5/de0/bit__reader_8cc_source.html#l00021" > bit_reader.cc:21< / a > < / div > < / div >
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