/usr/include/gnash/BitsReader.h is in gnash-dev 0.8.11~git20160109-1build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 | // BitsReader.h: bits reader, for Gnash.
//
// Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
// Free Software Foundation, Inc
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
//
#ifndef BITSREADER_H
#define BITSREADER_H
#include "dsodefs.h"
#include "log.h"
#include <cassert>
#include <cstdint> // for std::uint32_t used in this file
namespace gnash {
/// BitsReader is used to encapsulate bit-packed buffer reads.
//
/// TODO: implement boundary checking, maybe by throwing an exception
/// when attempts are made to read past end of buffer
///
class DSOEXPORT BitsReader
{
public:
typedef unsigned char byte;
/// Ownership of buffer left to caller
BitsReader(const byte* input, size_t len)
:
start(input),
ptr(start),
end(start+len),
usedBits(0)
{
}
/// Create a BitsReader reading a subset of another
//
/// The starting pointer will be taken from the parent
/// reader cursor, including used bits, use align() if
/// need to discard the left over ones.
///
/// length will be given explicitly.
///
BitsReader(const BitsReader& from, size_t len)
:
start(from.ptr),
ptr(start),
end(start+len),
usedBits(from.usedBits)
{
}
~BitsReader() {}
size_t size() const
{
return end-start;
}
/// Set a new buffer to work with
void setBuffer(byte* input, size_t len)
{
start = ptr = input;
end = start+len;
usedBits = 0;
}
/// \brief
/// Reads a bit-packed unsigned integer from the stream
/// and returns it. The given bitcount determines the
/// number of bits to read.
unsigned read_uint(unsigned short bitcount);
/// \brief
/// Reads a single bit off the stream
/// and returns it.
bool read_bit();
/// \brief
/// Reads a bit-packed little-endian signed integer
/// from the stream. The given bitcount determines the
/// number of bits to read.
std::int32_t read_sint(unsigned short bitcount);
/// Read a byte as an unsigned int (aligned)
std::uint8_t read_u8()
{
align();
return *ptr++;
}
/// Read one bytes as a signed int (aligned)
std::int8_t read_s8()
{
return static_cast<std::int8_t>(read_u8());
}
/// Read two bytes as an unsigned int (aligned)
std::uint16_t read_u16()
{
align();
assert(ptr+2 < end);
std::uint16_t result = *ptr++;
result |= *ptr++ << 8;
return result ;
}
/// Read two bytes as a signed int (aligned)
std::int16_t read_s16()
{
return static_cast<std::int16_t>(read_u16());
}
/// Read four bytes as an unsigned int (aligned)
std::uint32_t read_u32()
{
align();
assert(ptr+4 < end);
std::uint32_t result = *ptr++;
result |= *ptr++ << 8;
result |= *ptr++ << 16;
result |= *ptr++ << 24;
return(result);
}
/// Read four bytes as an signed int (aligned)
std::int32_t read_s32()
{
return static_cast<std::int32_t>(read_u32());
}
/// \brief
/// Discard any unused bit in the current byte
/// and advance to next
void align()
{
if ( usedBits ) advanceToNextByte();
}
/// Checks if the stream contains X bits
bool gotBits(std::uint32_t nbits) const
{
std::uint32_t gotbits = 8-usedBits +8*(end-ptr-1);
if (gotbits > nbits) return true;
else return false;
}
private:
void advanceToNextByte()
{
if ( ++ptr == end )
{
log_debug(_("Going round"));
ptr=start;
}
usedBits=0;
}
/// Pointer to first byte
const byte* start;
/// Pointer to current byte
const byte* ptr;
/// Pointer to one past last byte
const byte* end;
/// Number of used bits in current byte
unsigned usedBits;
};
} // end namespace gnash
#endif // BITSREADER_H
// Local Variables:
// mode: C++
// c-basic-offset: 8
// tab-width: 8
// indent-tabs-mode: t
// End:
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