diff options
Diffstat (limited to 'ml/dlib/dlib/entropy_encoder/entropy_encoder_kernel_2.cpp')
| -rw-r--r-- | ml/dlib/dlib/entropy_encoder/entropy_encoder_kernel_2.cpp | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/ml/dlib/dlib/entropy_encoder/entropy_encoder_kernel_2.cpp b/ml/dlib/dlib/entropy_encoder/entropy_encoder_kernel_2.cpp new file mode 100644 index 000000000..4f64a6155 --- /dev/null +++ b/ml/dlib/dlib/entropy_encoder/entropy_encoder_kernel_2.cpp @@ -0,0 +1,233 @@ +// Copyright (C) 2004 Davis E. King (davis@dlib.net) +// License: Boost Software License See LICENSE.txt for the full license. +#ifndef DLIB_ENTROPY_ENCODER_KERNEL_2_CPp_ +#define DLIB_ENTROPY_ENCODER_KERNEL_2_CPp_ +#include "entropy_encoder_kernel_2.h" +#include <iostream> +#include <streambuf> + +namespace dlib +{ + + +// ---------------------------------------------------------------------------------------- + + entropy_encoder_kernel_2:: + entropy_encoder_kernel_2( + ) : + initial_low(0x00000001), + initial_high(0xffffffff), + out(0), + low(initial_low), + high(initial_high) + { + } + +// ---------------------------------------------------------------------------------------- + + entropy_encoder_kernel_2:: + ~entropy_encoder_kernel_2 ( + ) + { + try { + if (out != 0) + { + flush(); + } + } catch (...) {} + } + +// ---------------------------------------------------------------------------------------- + + void entropy_encoder_kernel_2:: + clear( + ) + { + if (out != 0) + { + flush(); + } + out = 0; + } + +// ---------------------------------------------------------------------------------------- + + void entropy_encoder_kernel_2:: + set_stream ( + std::ostream& out_ + ) + { + if (out != 0) + { + // if a stream is currently set then flush the buffers to it before + // we switch to the new stream + flush(); + } + + out = &out_; + streambuf = out_.rdbuf(); + + // reset the encoder state + low = initial_low; + high = initial_high; + } + +// ---------------------------------------------------------------------------------------- + + bool entropy_encoder_kernel_2:: + stream_is_set ( + ) const + { + if (out != 0) + return true; + else + return false; + } + +// ---------------------------------------------------------------------------------------- + + std::ostream& entropy_encoder_kernel_2:: + get_stream ( + ) const + { + return *out; + } + +// ---------------------------------------------------------------------------------------- + + void entropy_encoder_kernel_2:: + encode ( + uint32 low_count, + uint32 high_count, + uint32 total + ) + { + // note that we must add one because of the convention that + // high == the real upper range minus 1 + uint32 r = (high-low+1)/total; + + // note that we must subtract 1 to preserve the convention that + // high == the real upper range - 1 + high = low + r*high_count-1; + low = low + r*low_count; + + + + while (true ) + { + + // if high and low don't have the same 8 high order bits + if ((high&0xFF000000) != (low&0xFF000000)) + { + // if the distance between high and low is small and there aren't + // any bits we can roll off then force high and low to have common high + // order bits. + if ((high-low < 0x10000)) + { + if (high-low > 0x1000) + { + high>>=1; + low>>=1; + high = low = high+low; + high += 0xFF; + low -= 0xFF; + } + else /**/ + { + high>>=1; + low>>=1; + high = low = high+low; + } + } + else + { + // there are no bits to roll off and high and low are not + // too close so just quit the loop + break; + } + + } + // else if there are 8 bits we can roll off + else + { + // write the 8 high order bits from low into buf + unsigned char buf = static_cast<unsigned char>(low>>24); + + + // roll off the bits we just wrote to buf + high <<= 8; + low <<= 8; + high |= 0xFF; // note that it is ok to add 0xFF to high here because + // of the convention that high == real upper range - 1. + // so that means that if we want to shift the upper range + // left by one then we must shift a one into high also + // since real upper range == high + 0.999999999... + + // make sure low is never zero + if (low == 0) + low = 1; + + // write buf to the output stream + if (streambuf->sputn(reinterpret_cast<char*>(&buf),1)==0) + { + throw std::ios_base::failure("error occurred in the entropy_encoder object"); + } + + } + + } // while (true) + + } + +// ---------------------------------------------------------------------------------------- + + void entropy_encoder_kernel_2:: + flush ( + ) + { + + // flush low to the output stream + + + unsigned char buf; + + + buf = static_cast<unsigned char>((low >> 24)&0xFF); + if (streambuf->sputn(reinterpret_cast<char*>(&buf),1) == 0) + throw std::ios_base::failure("error occurred in the entropy_encoder object"); + + + + + buf = static_cast<unsigned char>((low >> 16)&0xFF); + if (streambuf->sputn(reinterpret_cast<char*>(&buf),1)==0) + throw std::ios_base::failure("error occurred in the entropy_encoder object"); + + + + buf = static_cast<unsigned char>((low >> 8)&0xFF); + if (streambuf->sputn(reinterpret_cast<char*>(&buf),1)==0) + throw std::ios_base::failure("error occurred in the entropy_encoder object"); + + + buf = static_cast<unsigned char>((low)&0xFF); + if (streambuf->sputn(reinterpret_cast<char*>(&buf),1)==0) + throw std::ios_base::failure("error occurred in the entropy_encoder object"); + + + + + // make sure the stream buffer flushes to its I/O channel + streambuf->pubsync(); + + + // reset the encoder state + low = initial_low; + high = initial_high; + } + +// ---------------------------------------------------------------------------------------- + +} +#endif // DLIB_ENTROPY_ENCODER_KERNEL_2_CPp_ + |