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Diffstat (limited to 'ml/dlib/dlib/lzp_buffer/lzp_buffer_kernel_1.h')
| -rw-r--r-- | ml/dlib/dlib/lzp_buffer/lzp_buffer_kernel_1.h | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/ml/dlib/dlib/lzp_buffer/lzp_buffer_kernel_1.h b/ml/dlib/dlib/lzp_buffer/lzp_buffer_kernel_1.h new file mode 100644 index 000000000..f24d74eee --- /dev/null +++ b/ml/dlib/dlib/lzp_buffer/lzp_buffer_kernel_1.h @@ -0,0 +1,236 @@ +// Copyright (C) 2005 Davis E. King (davis@dlib.net) +// License: Boost Software License See LICENSE.txt for the full license. +#ifndef DLIB_LZP_BUFFER_KERNEl_1_ +#define DLIB_LZP_BUFFER_KERNEl_1_ + +#include "../algs.h" +#include "lzp_buffer_kernel_abstract.h" + +namespace dlib +{ + + template < + typename sbuf + > + class lzp_buffer_kernel_1 + { + /*! + REQUIREMENTS ON sbuf + sbuf is an implementation of sliding_buffer/sliding_buffer_kernel_abstract.h + T == unsigned char + + INITIAL VALUE + - buffer.size() == the size as defined by the constructor + - table_size == the number of elements in the table array + - for all i: buffer[i] == 0 + - for all i: table[i] == buffer.size() + + CONVENTION + - table_size == the number of elements in the table array + - size() == buffer.size() + - operator[](i) == buffer[i] + + - if (table[hash()] != buffer.size()) then + - buffer.get_element_index(table[hash()]) == the index we will + predict for the current context + - else + - there is no prediction for the current context + + - last_element == buffer.size()-1 + + + This is LZP with just an order-3 model without context confirmation. + + !*/ + + public: + + explicit lzp_buffer_kernel_1 ( + unsigned long buffer_size + ); + + virtual ~lzp_buffer_kernel_1 ( + ); + + void clear( + ); + + inline void add ( + unsigned char symbol + ); + + inline unsigned long predict_match ( + unsigned long& index + ); + + inline size_t size ( + ) const; + + inline unsigned char operator[] ( + unsigned long index + ) const; + + private: + + inline unsigned long hash ( + ) const + /*! + ensures + - returns a hash computed from the current context. This hash + is always in the range for table. + !*/ + { + unsigned long temp = buffer[0]; + temp <<= 16; + unsigned long temp2 = buffer[1]; + temp2 <<= 8; + unsigned long temp3 = buffer[2]; + temp = temp|temp2|temp3; + + temp = ((temp>>11)^temp)&0xFFFF; + + return temp; + } + + sbuf buffer; + const unsigned long table_size; + unsigned long* const table; + unsigned long last_element; + + // restricted functions + lzp_buffer_kernel_1(const lzp_buffer_kernel_1<sbuf>&); // copy constructor + lzp_buffer_kernel_1<sbuf>& operator=(const lzp_buffer_kernel_1<sbuf>&); // assignment operator + + }; + +// ---------------------------------------------------------------------------------------- +// ---------------------------------------------------------------------------------------- + // member function definitions +// ---------------------------------------------------------------------------------------- +// ---------------------------------------------------------------------------------------- + + template < + typename sbuf + > + lzp_buffer_kernel_1<sbuf>:: + lzp_buffer_kernel_1 ( + unsigned long buffer_size + ) : + table_size(65536), + table(new unsigned long[table_size]) + { + buffer.set_size(buffer_size); + + for (unsigned long i = 0; i < buffer.size(); ++i) + buffer[i] = 0; + + for (unsigned long i = 0; i < table_size; ++i) + table[i] = buffer.size(); + + last_element = buffer.size()-1; + } + +// ---------------------------------------------------------------------------------------- + + template < + typename sbuf + > + lzp_buffer_kernel_1<sbuf>:: + ~lzp_buffer_kernel_1 ( + ) + { + delete [] table; + } + +// ---------------------------------------------------------------------------------------- + + template < + typename sbuf + > + void lzp_buffer_kernel_1<sbuf>:: + clear( + ) + { + for (unsigned long i = 0; i < buffer.size(); ++i) + buffer[i] = 0; + + for (unsigned long i = 0; i < table_size; ++i) + table[i] = buffer.size(); + } + +// ---------------------------------------------------------------------------------------- + + template < + typename sbuf + > + void lzp_buffer_kernel_1<sbuf>:: + add ( + unsigned char symbol + ) + { + buffer.rotate_left(1); + buffer[0] = symbol; + } + +// ---------------------------------------------------------------------------------------- + + template < + typename sbuf + > + unsigned long lzp_buffer_kernel_1<sbuf>:: + predict_match ( + unsigned long& index + ) + { + const unsigned long i = hash(); + + if (table[i] != buffer.size()) + { + index = buffer.get_element_index(table[i]); + + if (index > 20) + { + // update the prediction for this context + table[i] = buffer.get_element_id(last_element); + } + return 3; + } + else + { + // update the prediction for this context + table[i] = buffer.get_element_id(last_element); + return 0; + } + } + +// ---------------------------------------------------------------------------------------- + + template < + typename sbuf + > + size_t lzp_buffer_kernel_1<sbuf>:: + size ( + ) const + { + return buffer.size(); + } + +// ---------------------------------------------------------------------------------------- + + template < + typename sbuf + > + unsigned char lzp_buffer_kernel_1<sbuf>:: + operator[] ( + unsigned long index + ) const + { + return buffer[index]; + } + +// ---------------------------------------------------------------------------------------- + +} + +#endif // DLIB_LZP_BUFFER_KERNEl_1_ + |