1 // Boost CRC library crc.hpp header file -----------------------------------//
3 // Copyright 2001, 2004 Daryle Walker. Use, modification, and distribution are
4 // subject to the Boost Software License, Version 1.0. (See accompanying file
5 // LICENSE_1_0.txt or a copy at <http://www.boost.org/LICENSE_1_0.txt>.)
7 // See <http://www.boost.org/libs/crc/> for the library's home page.
12 #include <boost/config.hpp> // for BOOST_STATIC_CONSTANT, etc.
13 #include <boost/integer.hpp> // for boost::uint_t
15 #include <climits> // for CHAR_BIT, etc.
16 #include <cstddef> // for std::size_t
18 #include <boost/limits.hpp> // for std::numeric_limits
21 // The type of CRC parameters that can go in a template should be related
22 // on the CRC's bit count. This macro expresses that type in a compact
23 // form, but also allows an alternate type for compilers that don't support
24 // dependent types (in template value-parameters).
25 #if !(defined(BOOST_NO_DEPENDENT_TYPES_IN_TEMPLATE_VALUE_PARAMETERS) || (defined(BOOST_MSVC) && (BOOST_MSVC <= 1300)))
26 #define BOOST_CRC_PARM_TYPE typename ::boost::uint_t<Bits>::fast
28 #define BOOST_CRC_PARM_TYPE unsigned long
31 // Some compilers [MS VC++ 6] cannot correctly set up several versions of a
32 // function template unless every template argument can be unambiguously
33 // deduced from the function arguments. (The bug is hidden if only one version
34 // is needed.) Since all of the CRC function templates have this problem, the
35 // workaround is to make up a dummy function argument that encodes the template
36 // arguments. Calls to such template functions need all their template
37 // arguments explicitly specified. At least one compiler that needs this
38 // workaround also needs the default value for the dummy argument to be
39 // specified in the definition.
40 #if defined(__GNUC__) || !defined(BOOST_NO_EXPLICIT_FUNCTION_TEMPLATE_ARGUMENTS)
41 #define BOOST_CRC_DUMMY_PARM_TYPE
42 #define BOOST_CRC_DUMMY_INIT
43 #define BOOST_ACRC_DUMMY_PARM_TYPE
44 #define BOOST_ACRC_DUMMY_INIT
46 namespace boost { namespace detail {
47 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
48 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
49 bool ReflectIn, bool ReflectRem >
50 struct dummy_crc_argument { };
52 #define BOOST_CRC_DUMMY_PARM_TYPE , detail::dummy_crc_argument<Bits, \
53 TruncPoly, InitRem, FinalXor, ReflectIn, ReflectRem> *p_
54 #define BOOST_CRC_DUMMY_INIT BOOST_CRC_DUMMY_PARM_TYPE = 0
55 #define BOOST_ACRC_DUMMY_PARM_TYPE , detail::dummy_crc_argument<Bits, \
56 TruncPoly, 0, 0, false, false> *p_
57 #define BOOST_ACRC_DUMMY_INIT BOOST_ACRC_DUMMY_PARM_TYPE = 0
65 // Forward declarations ----------------------------------------------------//
67 template < std::size_t Bits >
70 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly = 0u,
71 BOOST_CRC_PARM_TYPE InitRem = 0u,
72 BOOST_CRC_PARM_TYPE FinalXor = 0u, bool ReflectIn = false,
73 bool ReflectRem = false >
76 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
77 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
78 bool ReflectIn, bool ReflectRem >
79 typename uint_t<Bits>::fast crc( void const *buffer,
80 std::size_t byte_count
81 BOOST_CRC_DUMMY_PARM_TYPE );
83 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly >
84 typename uint_t<Bits>::fast augmented_crc( void const *buffer,
85 std::size_t byte_count, typename uint_t<Bits>::fast initial_remainder
86 BOOST_ACRC_DUMMY_PARM_TYPE );
88 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly >
89 typename uint_t<Bits>::fast augmented_crc( void const *buffer,
90 std::size_t byte_count
91 BOOST_ACRC_DUMMY_PARM_TYPE );
93 typedef crc_optimal<16, 0x8005, 0, 0, true, true> crc_16_type;
94 typedef crc_optimal<16, 0x1021, 0xFFFF, 0, false, false> crc_ccitt_type;
95 typedef crc_optimal<16, 0x8408, 0, 0, true, true> crc_xmodem_type;
97 typedef crc_optimal<32, 0x04C11DB7, 0xFFFFFFFF, 0xFFFFFFFF, true, true>
101 // Forward declarations for implementation detail stuff --------------------//
102 // (Just for the stuff that will be needed for the next two sections)
106 template < std::size_t Bits >
110 struct mask_uint_t< std::numeric_limits<unsigned char>::digits >;
112 #if USHRT_MAX > UCHAR_MAX
114 struct mask_uint_t< std::numeric_limits<unsigned short>::digits >;
117 #if UINT_MAX > USHRT_MAX
119 struct mask_uint_t< std::numeric_limits<unsigned int>::digits >;
122 #if ULONG_MAX > UINT_MAX
124 struct mask_uint_t< std::numeric_limits<unsigned long>::digits >;
127 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly, bool Reflect >
130 template < std::size_t Bits, bool DoReflect >
133 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
134 template < std::size_t Bits >
135 class crc_helper< Bits, false >;
138 } // namespace detail
141 // Simple cyclic redundancy code (CRC) class declaration -------------------//
143 template < std::size_t Bits >
146 // Implementation type
147 typedef detail::mask_uint_t<Bits> masking_type;
151 typedef typename masking_type::least value_type;
153 // Constant for the template parameter
154 BOOST_STATIC_CONSTANT( std::size_t, bit_count = Bits );
157 explicit crc_basic( value_type truncated_polynominal,
158 value_type initial_remainder = 0, value_type final_xor_value = 0,
159 bool reflect_input = false, bool reflect_remainder = false );
161 // Internal Operations
162 value_type get_truncated_polynominal() const;
163 value_type get_initial_remainder() const;
164 value_type get_final_xor_value() const;
165 bool get_reflect_input() const;
166 bool get_reflect_remainder() const;
168 value_type get_interim_remainder() const;
169 void reset( value_type new_rem );
172 // External Operations
173 void process_bit( bool bit );
174 void process_bits( unsigned char bits, std::size_t bit_count );
175 void process_byte( unsigned char byte );
176 void process_block( void const *bytes_begin, void const *bytes_end );
177 void process_bytes( void const *buffer, std::size_t byte_count );
179 value_type checksum() const;
184 value_type poly_, init_, final_; // non-const to allow assignability
185 bool rft_in_, rft_out_; // non-const to allow assignability
187 }; // boost::crc_basic
190 // Optimized cyclic redundancy code (CRC) class declaration ----------------//
192 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
193 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
194 bool ReflectIn, bool ReflectRem >
197 // Implementation type
198 typedef detail::mask_uint_t<Bits> masking_type;
202 typedef typename masking_type::fast value_type;
204 // Constants for the template parameters
205 BOOST_STATIC_CONSTANT( std::size_t, bit_count = Bits );
206 BOOST_STATIC_CONSTANT( value_type, truncated_polynominal = TruncPoly );
207 BOOST_STATIC_CONSTANT( value_type, initial_remainder = InitRem );
208 BOOST_STATIC_CONSTANT( value_type, final_xor_value = FinalXor );
209 BOOST_STATIC_CONSTANT( bool, reflect_input = ReflectIn );
210 BOOST_STATIC_CONSTANT( bool, reflect_remainder = ReflectRem );
213 explicit crc_optimal( value_type init_rem = InitRem );
215 // Internal Operations
216 value_type get_truncated_polynominal() const;
217 value_type get_initial_remainder() const;
218 value_type get_final_xor_value() const;
219 bool get_reflect_input() const;
220 bool get_reflect_remainder() const;
222 value_type get_interim_remainder() const;
223 void reset( value_type new_rem = InitRem );
225 // External Operations
226 void process_byte( unsigned char byte );
227 void process_block( void const *bytes_begin, void const *bytes_end );
228 void process_bytes( void const *buffer, std::size_t byte_count );
230 value_type checksum() const;
233 void operator ()( unsigned char byte );
234 value_type operator ()() const;
237 // The implementation of output reflection depends on both reflect states.
238 BOOST_STATIC_CONSTANT( bool, reflect_output = (ReflectRem != ReflectIn) );
241 #define BOOST_CRC_REF_OUT_VAL reflect_output
243 typedef crc_optimal self_type;
244 #define BOOST_CRC_REF_OUT_VAL (self_type::reflect_output)
247 // More implementation types
248 typedef detail::crc_table_t<Bits, TruncPoly, ReflectIn> crc_table_type;
249 typedef detail::crc_helper<Bits, ReflectIn> helper_type;
250 typedef detail::crc_helper<Bits, BOOST_CRC_REF_OUT_VAL> reflect_out_type;
252 #undef BOOST_CRC_REF_OUT_VAL
257 }; // boost::crc_optimal
260 // Implementation detail stuff ---------------------------------------------//
264 // Forward declarations for more implementation details
265 template < std::size_t Bits >
268 template < std::size_t Bits >
272 // Traits class for mask; given the bit number
273 // (1-based), get the mask for that bit by itself.
274 template < std::size_t Bits >
276 : boost::uint_t< Bits >
278 typedef boost::uint_t<Bits> base_type;
279 typedef typename base_type::least least;
280 typedef typename base_type::fast fast;
282 #if defined(__EDG_VERSION__) && __EDG_VERSION__ <= 243
283 static const least high_bit = 1ul << ( Bits - 1u );
284 static const fast high_bit_fast = 1ul << ( Bits - 1u );
286 BOOST_STATIC_CONSTANT( least, high_bit = (least( 1u ) << ( Bits
288 BOOST_STATIC_CONSTANT( fast, high_bit_fast = (fast( 1u ) << ( Bits
292 }; // boost::detail::high_uint_t
295 // Reflection routine class wrapper
296 // (since MS VC++ 6 couldn't handle the unwrapped version)
297 template < std::size_t Bits >
300 typedef typename boost::uint_t<Bits>::fast value_type;
302 static value_type reflect( value_type x );
304 }; // boost::detail::reflector
306 // Function that reflects its argument
307 template < std::size_t Bits >
308 typename reflector<Bits>::value_type
309 reflector<Bits>::reflect
311 typename reflector<Bits>::value_type x
314 value_type reflection = 0;
315 value_type const one = 1;
317 for ( std::size_t i = 0 ; i < Bits ; ++i, x >>= 1 )
321 reflection |= ( one << (Bits - 1u - i) );
329 // Traits class for masks; given the bit number (1-based),
330 // get the mask for that bit and its lower bits.
331 template < std::size_t Bits >
333 : high_uint_t< Bits >
335 typedef high_uint_t<Bits> base_type;
336 typedef typename base_type::least least;
337 typedef typename base_type::fast fast;
340 using base_type::high_bit;
341 using base_type::high_bit_fast;
343 BOOST_STATIC_CONSTANT( least, high_bit = base_type::high_bit );
344 BOOST_STATIC_CONSTANT( fast, high_bit_fast = base_type::high_bit_fast );
347 #if defined(__EDG_VERSION__) && __EDG_VERSION__ <= 243
348 static const least sig_bits = (~( ~( 0ul ) << Bits )) ;
350 BOOST_STATIC_CONSTANT( least, sig_bits = (~( ~(least( 0u )) << Bits )) );
352 #if defined(__GNUC__) && __GNUC__ == 4 && __GNUC_MINOR__ == 0 && __GNUC_PATCHLEVEL__ == 2
353 // Work around a weird bug that ICEs the compiler in build_c_cast
354 BOOST_STATIC_CONSTANT( fast, sig_bits_fast = static_cast<fast>(sig_bits) );
356 BOOST_STATIC_CONSTANT( fast, sig_bits_fast = fast(sig_bits) );
358 }; // boost::detail::mask_uint_t
361 struct mask_uint_t< std::numeric_limits<unsigned char>::digits >
362 : high_uint_t< std::numeric_limits<unsigned char>::digits >
364 typedef high_uint_t<std::numeric_limits<unsigned char>::digits>
366 typedef base_type::least least;
367 typedef base_type::fast fast;
370 using base_type::high_bit;
371 using base_type::high_bit_fast;
373 BOOST_STATIC_CONSTANT( least, high_bit = base_type::high_bit );
374 BOOST_STATIC_CONSTANT( fast, high_bit_fast = base_type::high_bit_fast );
377 BOOST_STATIC_CONSTANT( least, sig_bits = (~( least(0u) )) );
378 BOOST_STATIC_CONSTANT( fast, sig_bits_fast = fast(sig_bits) );
380 }; // boost::detail::mask_uint_t
382 #if USHRT_MAX > UCHAR_MAX
384 struct mask_uint_t< std::numeric_limits<unsigned short>::digits >
385 : high_uint_t< std::numeric_limits<unsigned short>::digits >
387 typedef high_uint_t<std::numeric_limits<unsigned short>::digits>
389 typedef base_type::least least;
390 typedef base_type::fast fast;
393 using base_type::high_bit;
394 using base_type::high_bit_fast;
396 BOOST_STATIC_CONSTANT( least, high_bit = base_type::high_bit );
397 BOOST_STATIC_CONSTANT( fast, high_bit_fast = base_type::high_bit_fast );
400 BOOST_STATIC_CONSTANT( least, sig_bits = (~( least(0u) )) );
401 BOOST_STATIC_CONSTANT( fast, sig_bits_fast = fast(sig_bits) );
403 }; // boost::detail::mask_uint_t
406 #if UINT_MAX > USHRT_MAX
408 struct mask_uint_t< std::numeric_limits<unsigned int>::digits >
409 : high_uint_t< std::numeric_limits<unsigned int>::digits >
411 typedef high_uint_t<std::numeric_limits<unsigned int>::digits>
413 typedef base_type::least least;
414 typedef base_type::fast fast;
417 using base_type::high_bit;
418 using base_type::high_bit_fast;
420 BOOST_STATIC_CONSTANT( least, high_bit = base_type::high_bit );
421 BOOST_STATIC_CONSTANT( fast, high_bit_fast = base_type::high_bit_fast );
424 BOOST_STATIC_CONSTANT( least, sig_bits = (~( least(0u) )) );
425 BOOST_STATIC_CONSTANT( fast, sig_bits_fast = fast(sig_bits) );
427 }; // boost::detail::mask_uint_t
430 #if ULONG_MAX > UINT_MAX
432 struct mask_uint_t< std::numeric_limits<unsigned long>::digits >
433 : high_uint_t< std::numeric_limits<unsigned long>::digits >
435 typedef high_uint_t<std::numeric_limits<unsigned long>::digits>
437 typedef base_type::least least;
438 typedef base_type::fast fast;
441 using base_type::high_bit;
442 using base_type::high_bit_fast;
444 BOOST_STATIC_CONSTANT( least, high_bit = base_type::high_bit );
445 BOOST_STATIC_CONSTANT( fast, high_bit_fast = base_type::high_bit_fast );
448 BOOST_STATIC_CONSTANT( least, sig_bits = (~( least(0u) )) );
449 BOOST_STATIC_CONSTANT( fast, sig_bits_fast = fast(sig_bits) );
451 }; // boost::detail::mask_uint_t
455 // CRC table generator
456 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly, bool Reflect >
459 BOOST_STATIC_CONSTANT( std::size_t, byte_combos = (1ul << CHAR_BIT) );
461 typedef mask_uint_t<Bits> masking_type;
462 typedef typename masking_type::fast value_type;
463 #if defined(__BORLANDC__) && defined(_M_IX86) && (__BORLANDC__ == 0x560)
464 // for some reason Borland's command line compiler (version 0x560)
465 // chokes over this unless we do the calculation for it:
466 typedef value_type table_type[ 0x100 ];
467 #elif defined(__GNUC__)
468 // old versions of GCC (before 4.0.2) choke on using byte_combos
469 // as a constant expression when compiling with -pedantic.
470 typedef value_type table_type[1ul << CHAR_BIT];
472 typedef value_type table_type[ byte_combos ];
475 static void init_table();
477 static table_type table_;
479 }; // boost::detail::crc_table_t
481 // CRC table generator static data member definition
482 // (Some compilers [Borland C++] require the initializer to be present.)
483 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly, bool Reflect >
484 typename crc_table_t<Bits, TruncPoly, Reflect>::table_type
485 crc_table_t<Bits, TruncPoly, Reflect>::table_
488 // Populate CRC lookup table
489 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly, bool Reflect >
491 crc_table_t<Bits, TruncPoly, Reflect>::init_table
495 // compute table only on the first run
496 static bool did_init = false;
497 if ( did_init ) return;
499 // factor-out constants to avoid recalculation
500 value_type const fast_hi_bit = masking_type::high_bit_fast;
501 unsigned char const byte_hi_bit = 1u << (CHAR_BIT - 1u);
503 // loop over every possible dividend value
504 unsigned char dividend = 0;
507 value_type remainder = 0;
509 // go through all the dividend's bits
510 for ( unsigned char mask = byte_hi_bit ; mask ; mask >>= 1 )
512 // check if divisor fits
513 if ( dividend & mask )
515 remainder ^= fast_hi_bit;
518 // do polynominal division
519 if ( remainder & fast_hi_bit )
522 remainder ^= TruncPoly;
530 table_[ crc_helper<CHAR_BIT, Reflect>::reflect(dividend) ]
531 = crc_helper<Bits, Reflect>::reflect( remainder );
533 while ( ++dividend );
538 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
539 // Align the msb of the remainder to a byte
540 template < std::size_t Bits, bool RightShift >
544 typedef typename uint_t<Bits>::fast value_type;
546 static unsigned char align_msb( value_type rem )
547 { return rem >> (Bits - CHAR_BIT); }
550 // Specialization for the case that the remainder has less
551 // bits than a byte: align the remainder msb to the byte msb
552 template < std::size_t Bits >
553 class remainder< Bits, false >
556 typedef typename uint_t<Bits>::fast value_type;
558 static unsigned char align_msb( value_type rem )
559 { return rem << (CHAR_BIT - Bits); }
563 // CRC helper routines
564 template < std::size_t Bits, bool DoReflect >
569 typedef typename uint_t<Bits>::fast value_type;
571 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
572 // Possibly reflect a remainder
573 static value_type reflect( value_type x )
574 { return detail::reflector<Bits>::reflect( x ); }
576 // Compare a byte to the remainder's highest byte
577 static unsigned char index( value_type rem, unsigned char x )
580 // Shift out the remainder's highest byte
581 static value_type shift( value_type rem )
582 { return rem >> CHAR_BIT; }
584 // Possibly reflect a remainder
585 static value_type reflect( value_type x )
586 { return DoReflect ? detail::reflector<Bits>::reflect( x ) : x; }
588 // Compare a byte to the remainder's highest byte
589 static unsigned char index( value_type rem, unsigned char x )
590 { return x ^ ( DoReflect ? rem :
591 ((Bits>CHAR_BIT)?( rem >> (Bits - CHAR_BIT) ) :
592 ( rem << (CHAR_BIT - Bits) ))); }
594 // Shift out the remainder's highest byte
595 static value_type shift( value_type rem )
596 { return DoReflect ? rem >> CHAR_BIT : rem << CHAR_BIT; }
599 }; // boost::detail::crc_helper
601 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
602 template < std::size_t Bits >
603 class crc_helper<Bits, false>
607 typedef typename uint_t<Bits>::fast value_type;
609 // Possibly reflect a remainder
610 static value_type reflect( value_type x )
613 // Compare a byte to the remainder's highest byte
614 static unsigned char index( value_type rem, unsigned char x )
615 { return x ^ remainder<Bits,(Bits>CHAR_BIT)>::align_msb( rem ); }
617 // Shift out the remainder's highest byte
618 static value_type shift( value_type rem )
619 { return rem << CHAR_BIT; }
621 }; // boost::detail::crc_helper
625 } // namespace detail
628 // Simple CRC class function definitions -----------------------------------//
630 template < std::size_t Bits >
632 crc_basic<Bits>::crc_basic
634 typename crc_basic<Bits>::value_type truncated_polynominal,
635 typename crc_basic<Bits>::value_type initial_remainder, // = 0
636 typename crc_basic<Bits>::value_type final_xor_value, // = 0
637 bool reflect_input, // = false
638 bool reflect_remainder // = false
640 : rem_( initial_remainder ), poly_( truncated_polynominal )
641 , init_( initial_remainder ), final_( final_xor_value )
642 , rft_in_( reflect_input ), rft_out_( reflect_remainder )
646 template < std::size_t Bits >
648 typename crc_basic<Bits>::value_type
649 crc_basic<Bits>::get_truncated_polynominal
656 template < std::size_t Bits >
658 typename crc_basic<Bits>::value_type
659 crc_basic<Bits>::get_initial_remainder
666 template < std::size_t Bits >
668 typename crc_basic<Bits>::value_type
669 crc_basic<Bits>::get_final_xor_value
676 template < std::size_t Bits >
679 crc_basic<Bits>::get_reflect_input
686 template < std::size_t Bits >
689 crc_basic<Bits>::get_reflect_remainder
696 template < std::size_t Bits >
698 typename crc_basic<Bits>::value_type
699 crc_basic<Bits>::get_interim_remainder
703 return rem_ & masking_type::sig_bits;
706 template < std::size_t Bits >
709 crc_basic<Bits>::reset
711 typename crc_basic<Bits>::value_type new_rem
717 template < std::size_t Bits >
720 crc_basic<Bits>::reset
724 this->reset( this->get_initial_remainder() );
727 template < std::size_t Bits >
730 crc_basic<Bits>::process_bit
735 value_type const high_bit_mask = masking_type::high_bit;
737 // compare the new bit with the remainder's highest
738 rem_ ^= ( bit ? high_bit_mask : 0u );
740 // a full polynominal division step is done when the highest bit is one
741 bool const do_poly_div = static_cast<bool>( rem_ & high_bit_mask );
743 // shift out the highest bit
746 // carry out the division, if needed
753 template < std::size_t Bits >
755 crc_basic<Bits>::process_bits
758 std::size_t bit_count
761 // ignore the bits above the ones we want
762 bits <<= CHAR_BIT - bit_count;
764 // compute the CRC for each bit, starting with the upper ones
765 unsigned char const high_bit_mask = 1u << ( CHAR_BIT - 1u );
766 for ( std::size_t i = bit_count ; i > 0u ; --i, bits <<= 1u )
768 process_bit( static_cast<bool>(bits & high_bit_mask) );
772 template < std::size_t Bits >
775 crc_basic<Bits>::process_byte
780 process_bits( (rft_in_ ? detail::reflector<CHAR_BIT>::reflect(byte)
784 template < std::size_t Bits >
786 crc_basic<Bits>::process_block
788 void const * bytes_begin,
789 void const * bytes_end
792 for ( unsigned char const * p
793 = static_cast<unsigned char const *>(bytes_begin) ; p < bytes_end ; ++p )
799 template < std::size_t Bits >
802 crc_basic<Bits>::process_bytes
805 std::size_t byte_count
808 unsigned char const * const b = static_cast<unsigned char const *>(
811 process_block( b, b + byte_count );
814 template < std::size_t Bits >
816 typename crc_basic<Bits>::value_type
817 crc_basic<Bits>::checksum
821 return ( (rft_out_ ? detail::reflector<Bits>::reflect( rem_ ) : rem_)
822 ^ final_ ) & masking_type::sig_bits;
826 // Optimized CRC class function definitions --------------------------------//
828 // Macro to compact code
829 #define BOOST_CRC_OPTIMAL_NAME crc_optimal<Bits, TruncPoly, InitRem, \
830 FinalXor, ReflectIn, ReflectRem>
832 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
833 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
834 bool ReflectIn, bool ReflectRem >
836 BOOST_CRC_OPTIMAL_NAME::crc_optimal
838 typename BOOST_CRC_OPTIMAL_NAME::value_type init_rem // = InitRem
840 : rem_( helper_type::reflect(init_rem) )
842 crc_table_type::init_table();
845 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
846 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
847 bool ReflectIn, bool ReflectRem >
849 typename BOOST_CRC_OPTIMAL_NAME::value_type
850 BOOST_CRC_OPTIMAL_NAME::get_truncated_polynominal
857 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
858 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
859 bool ReflectIn, bool ReflectRem >
861 typename BOOST_CRC_OPTIMAL_NAME::value_type
862 BOOST_CRC_OPTIMAL_NAME::get_initial_remainder
869 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
870 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
871 bool ReflectIn, bool ReflectRem >
873 typename BOOST_CRC_OPTIMAL_NAME::value_type
874 BOOST_CRC_OPTIMAL_NAME::get_final_xor_value
881 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
882 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
883 bool ReflectIn, bool ReflectRem >
886 BOOST_CRC_OPTIMAL_NAME::get_reflect_input
893 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
894 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
895 bool ReflectIn, bool ReflectRem >
898 BOOST_CRC_OPTIMAL_NAME::get_reflect_remainder
905 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
906 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
907 bool ReflectIn, bool ReflectRem >
909 typename BOOST_CRC_OPTIMAL_NAME::value_type
910 BOOST_CRC_OPTIMAL_NAME::get_interim_remainder
914 // Interim remainder should be _un_-reflected, so we have to undo it.
915 return helper_type::reflect( rem_ ) & masking_type::sig_bits_fast;
918 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
919 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
920 bool ReflectIn, bool ReflectRem >
923 BOOST_CRC_OPTIMAL_NAME::reset
925 typename BOOST_CRC_OPTIMAL_NAME::value_type new_rem // = InitRem
928 rem_ = helper_type::reflect( new_rem );
931 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
932 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
933 bool ReflectIn, bool ReflectRem >
936 BOOST_CRC_OPTIMAL_NAME::process_byte
941 process_bytes( &byte, sizeof(byte) );
944 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
945 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
946 bool ReflectIn, bool ReflectRem >
948 BOOST_CRC_OPTIMAL_NAME::process_block
950 void const * bytes_begin,
951 void const * bytes_end
954 // Recompute the CRC for each byte passed
955 for ( unsigned char const * p
956 = static_cast<unsigned char const *>(bytes_begin) ; p < bytes_end ; ++p )
958 // Compare the new byte with the remainder's higher bits to
959 // get the new bits, shift out the remainder's current higher
960 // bits, and update the remainder with the polynominal division
962 unsigned char const byte_index = helper_type::index( rem_, *p );
963 rem_ = helper_type::shift( rem_ );
964 rem_ ^= crc_table_type::table_[ byte_index ];
968 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
969 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
970 bool ReflectIn, bool ReflectRem >
973 BOOST_CRC_OPTIMAL_NAME::process_bytes
976 std::size_t byte_count
979 unsigned char const * const b = static_cast<unsigned char const *>(
981 process_block( b, b + byte_count );
984 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
985 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
986 bool ReflectIn, bool ReflectRem >
988 typename BOOST_CRC_OPTIMAL_NAME::value_type
989 BOOST_CRC_OPTIMAL_NAME::checksum
993 return ( reflect_out_type::reflect(rem_) ^ get_final_xor_value() )
994 & masking_type::sig_bits_fast;
997 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
998 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
999 bool ReflectIn, bool ReflectRem >
1002 BOOST_CRC_OPTIMAL_NAME::operator ()
1007 process_byte( byte );
1010 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
1011 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
1012 bool ReflectIn, bool ReflectRem >
1014 typename BOOST_CRC_OPTIMAL_NAME::value_type
1015 BOOST_CRC_OPTIMAL_NAME::operator ()
1023 // CRC computation function definition -------------------------------------//
1025 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly,
1026 BOOST_CRC_PARM_TYPE InitRem, BOOST_CRC_PARM_TYPE FinalXor,
1027 bool ReflectIn, bool ReflectRem >
1029 typename uint_t<Bits>::fast
1032 void const * buffer,
1033 std::size_t byte_count
1034 BOOST_CRC_DUMMY_INIT
1037 BOOST_CRC_OPTIMAL_NAME computer;
1038 computer.process_bytes( buffer, byte_count );
1039 return computer.checksum();
1043 // Augmented-message CRC computation function definitions ------------------//
1045 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly >
1046 typename uint_t<Bits>::fast
1049 void const * buffer,
1050 std::size_t byte_count,
1051 typename uint_t<Bits>::fast initial_remainder
1052 BOOST_ACRC_DUMMY_INIT
1055 typedef unsigned char byte_type;
1056 typedef detail::mask_uint_t<Bits> masking_type;
1057 typedef detail::crc_table_t<Bits, TruncPoly, false> crc_table_type;
1059 typename masking_type::fast rem = initial_remainder;
1060 byte_type const * const b = static_cast<byte_type const *>( buffer );
1061 byte_type const * const e = b + byte_count;
1063 crc_table_type::init_table();
1064 for ( byte_type const * p = b ; p < e ; ++p )
1066 // Use the current top byte as the table index to the next
1067 // "partial product." Shift out that top byte, shifting in
1068 // the next augmented-message byte. Complete the division.
1069 byte_type const byte_index = rem >> ( Bits - CHAR_BIT );
1072 rem ^= crc_table_type::table_[ byte_index ];
1075 return rem & masking_type::sig_bits_fast;
1078 template < std::size_t Bits, BOOST_CRC_PARM_TYPE TruncPoly >
1080 typename uint_t<Bits>::fast
1083 void const * buffer,
1084 std::size_t byte_count
1085 BOOST_ACRC_DUMMY_INIT
1088 // The last function argument has its type specified so the other version of
1089 // augmented_crc will be called. If the cast wasn't in place, and the
1090 // BOOST_ACRC_DUMMY_INIT added a third argument (for a workaround), the "0"
1091 // would match as that third argument, leading to infinite recursion.
1092 return augmented_crc<Bits, TruncPoly>( buffer, byte_count,
1093 static_cast<typename uint_t<Bits>::fast>(0) );
1097 } // namespace boost
1100 // Undo header-private macros
1101 #undef BOOST_CRC_OPTIMAL_NAME
1102 #undef BOOST_ACRC_DUMMY_INIT
1103 #undef BOOST_ACRC_DUMMY_PARM_TYPE
1104 #undef BOOST_CRC_DUMMY_INIT
1105 #undef BOOST_CRC_DUMMY_PARM_TYPE
1106 #undef BOOST_CRC_PARM_TYPE
1109 #endif // BOOST_CRC_HPP