254 lines
13 KiB
C++
254 lines
13 KiB
C++
///////////////////////////////////////////////////////////////
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// Copyright 2015 John Maddock. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_
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#ifndef BOOST_MP_CPP_INT_IMPORT_EXPORT_HPP
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#define BOOST_MP_CPP_INT_IMPORT_EXPORT_HPP
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namespace boost {
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namespace multiprecision {
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namespace detail {
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template <class Backend, class Unsigned>
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void assign_bits(Backend& val, Unsigned bits, unsigned bit_location, unsigned chunk_bits, const mpl::false_& tag)
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{
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unsigned limb = bit_location / (sizeof(limb_type) * CHAR_BIT);
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unsigned shift = bit_location % (sizeof(limb_type) * CHAR_BIT);
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limb_type mask = chunk_bits >= sizeof(limb_type) * CHAR_BIT ? ~static_cast<limb_type>(0u) : (static_cast<limb_type>(1u) << chunk_bits) - 1;
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limb_type value = (static_cast<limb_type>(bits) & mask) << shift;
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if(value)
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{
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if(val.size() == limb)
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{
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val.resize(limb + 1, limb + 1);
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if(val.size() > limb)
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val.limbs()[limb] = value;
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}
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else if(val.size() > limb)
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val.limbs()[limb] |= value;
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}
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if(chunk_bits > sizeof(limb_type) * CHAR_BIT - shift)
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{
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shift = sizeof(limb_type) * CHAR_BIT - shift;
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chunk_bits -= shift;
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bit_location += shift;
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bits >>= shift;
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if(bits)
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assign_bits(val, bits, bit_location, chunk_bits, tag);
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}
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}
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template <class Backend, class Unsigned>
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void assign_bits(Backend& val, Unsigned bits, unsigned bit_location, unsigned chunk_bits, const mpl::true_&)
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{
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typedef typename Backend::local_limb_type local_limb_type;
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//
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// Check for possible overflow, this may trigger an exception, or have no effect
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// depending on whether this is a checked integer or not:
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//
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if((bit_location >= sizeof(local_limb_type) * CHAR_BIT) && bits)
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val.resize(2, 2);
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else
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{
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local_limb_type mask = chunk_bits >= sizeof(local_limb_type) * CHAR_BIT ? ~static_cast<local_limb_type>(0u) : (static_cast<local_limb_type>(1u) << chunk_bits) - 1;
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local_limb_type value = (static_cast<local_limb_type>(bits) & mask) << bit_location;
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*val.limbs() |= value;
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//
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// Check for overflow bits:
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//
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bit_location = sizeof(local_limb_type) * CHAR_BIT - bit_location;
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bits >>= bit_location;
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if(bits)
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val.resize(2, 2); // May throw!
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}
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}
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template <unsigned MinBits, unsigned MaxBits, cpp_integer_type SignType, cpp_int_check_type Checked, class Allocator>
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inline void resize_to_bit_size(cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>& newval, unsigned bits, const mpl::false_&)
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{
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unsigned limb_count = static_cast<unsigned>(bits / (sizeof(limb_type) * CHAR_BIT));
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if(bits % (sizeof(limb_type) * CHAR_BIT))
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++limb_count;
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static const unsigned max_limbs = MaxBits ? MaxBits / (CHAR_BIT * sizeof(limb_type)) + ((MaxBits % (CHAR_BIT * sizeof(limb_type))) ? 1 : 0) : (std::numeric_limits<unsigned>::max)();
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if(limb_count > max_limbs)
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limb_count = max_limbs;
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newval.resize(limb_count, limb_count);
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std::memset(newval.limbs(), 0, newval.size() * sizeof(limb_type));
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}
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template <unsigned MinBits, unsigned MaxBits, cpp_integer_type SignType, cpp_int_check_type Checked, class Allocator>
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inline void resize_to_bit_size(cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>& newval, unsigned, const mpl::true_&)
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{
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*newval.limbs() = 0;
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}
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template <unsigned MinBits, unsigned MaxBits, cpp_integer_type SignType, cpp_int_check_type Checked, class Allocator, expression_template_option ExpressionTemplates, class Iterator>
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number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>&
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import_bits_generic(
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number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>& val, Iterator i, Iterator j, unsigned chunk_size = 0, bool msv_first = true)
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{
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typename number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>::backend_type newval;
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typedef typename std::iterator_traits<Iterator>::value_type value_type;
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typedef typename boost::make_unsigned<value_type>::type unsigned_value_type;
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typedef typename std::iterator_traits<Iterator>::difference_type difference_type;
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typedef typename boost::make_unsigned<difference_type>::type size_type;
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typedef typename cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>::trivial_tag tag_type;
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if(!chunk_size)
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chunk_size = std::numeric_limits<value_type>::digits;
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size_type limbs = std::distance(i, j);
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size_type bits = limbs * chunk_size;
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detail::resize_to_bit_size(newval, static_cast<unsigned>(bits), tag_type());
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difference_type bit_location = msv_first ? bits - chunk_size : 0;
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difference_type bit_location_change = msv_first ? -static_cast<difference_type>(chunk_size) : chunk_size;
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while(i != j)
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{
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detail::assign_bits(newval, static_cast<unsigned_value_type>(*i), static_cast<unsigned>(bit_location), chunk_size, tag_type());
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++i;
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bit_location += bit_location_change;
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}
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newval.normalize();
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val.backend().swap(newval);
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return val;
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}
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template <unsigned MinBits, unsigned MaxBits, cpp_integer_type SignType, cpp_int_check_type Checked, class Allocator, expression_template_option ExpressionTemplates, class T>
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inline typename boost::disable_if_c<boost::multiprecision::backends::is_trivial_cpp_int<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator> >::value, number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>&>::type
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import_bits_fast(
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number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>& val, T* i, T* j, unsigned chunk_size = 0)
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{
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std::size_t byte_len = (j - i) * (chunk_size ? chunk_size / CHAR_BIT : sizeof(*i));
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std::size_t limb_len = byte_len / sizeof(limb_type);
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if(byte_len % sizeof(limb_type))
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++limb_len;
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cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>& result = val.backend();
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result.resize(limb_len, limb_len); // checked types may throw here if they're not large enough to hold the data!
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result.limbs()[result.size() - 1] = 0u;
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std::memcpy(result.limbs(), i, std::min(byte_len, result.size() * sizeof(limb_type)));
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result.normalize(); // In case data has leading zeros.
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return val;
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}
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template <unsigned MinBits, unsigned MaxBits, cpp_integer_type SignType, cpp_int_check_type Checked, class Allocator, expression_template_option ExpressionTemplates, class T>
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inline typename boost::enable_if_c<boost::multiprecision::backends::is_trivial_cpp_int<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator> >::value, number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>&>::type
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import_bits_fast(
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number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>& val, T* i, T* j, unsigned chunk_size = 0)
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{
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cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>& result = val.backend();
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std::size_t byte_len = (j - i) * (chunk_size ? chunk_size / CHAR_BIT : sizeof(*i));
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std::size_t limb_len = byte_len / sizeof(result.limbs()[0]);
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if(byte_len % sizeof(result.limbs()[0]))
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++limb_len;
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result.limbs()[0] = 0u;
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result.resize(limb_len, limb_len); // checked types may throw here if they're not large enough to hold the data!
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std::memcpy(result.limbs(), i, std::min(byte_len, result.size() * sizeof(result.limbs()[0])));
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result.normalize(); // In case data has leading zeros.
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return val;
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}
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}
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template <unsigned MinBits, unsigned MaxBits, cpp_integer_type SignType, cpp_int_check_type Checked, class Allocator, expression_template_option ExpressionTemplates, class Iterator>
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inline number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>&
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import_bits(
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number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>& val, Iterator i, Iterator j, unsigned chunk_size = 0, bool msv_first = true)
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{
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return detail::import_bits_generic(val, i, j, chunk_size, msv_first);
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}
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template <unsigned MinBits, unsigned MaxBits, cpp_integer_type SignType, cpp_int_check_type Checked, class Allocator, expression_template_option ExpressionTemplates, class T>
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inline number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>&
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import_bits(
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number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>& val, T* i, T* j, unsigned chunk_size = 0, bool msv_first = true)
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{
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#ifdef BOOST_LITTLE_ENDIAN
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if(((chunk_size % CHAR_BIT) == 0) && !msv_first)
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return detail::import_bits_fast(val, i, j, chunk_size);
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#endif
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return detail::import_bits_generic(val, i, j, chunk_size, msv_first);
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}
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namespace detail {
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template <class Backend>
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std::uintmax_t extract_bits(const Backend& val, unsigned location, unsigned count, const mpl::false_& tag)
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{
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unsigned limb = location / (sizeof(limb_type) * CHAR_BIT);
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unsigned shift = location % (sizeof(limb_type) * CHAR_BIT);
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std::uintmax_t result = 0;
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std::uintmax_t mask = count == std::numeric_limits<std::uintmax_t>::digits ? ~static_cast<std::uintmax_t>(0) : (static_cast<std::uintmax_t>(1u) << count) - 1;
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if(count > (sizeof(limb_type) * CHAR_BIT - shift))
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{
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result = extract_bits(val, location + sizeof(limb_type) * CHAR_BIT - shift, count - sizeof(limb_type) * CHAR_BIT + shift, tag);
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result <<= sizeof(limb_type) * CHAR_BIT - shift;
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}
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if(limb < val.size())
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result |= (val.limbs()[limb] >> shift) & mask;
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return result;
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}
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template <class Backend>
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inline std::uintmax_t extract_bits(const Backend& val, unsigned location, unsigned count, const mpl::true_&)
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{
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std::uintmax_t result = *val.limbs();
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std::uintmax_t mask = count == std::numeric_limits<std::uintmax_t>::digits ? ~static_cast<std::uintmax_t>(0) : (static_cast<std::uintmax_t>(1u) << count) - 1;
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return (result >> location) & mask;
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}
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}
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template <unsigned MinBits, unsigned MaxBits, cpp_integer_type SignType, cpp_int_check_type Checked, class Allocator, expression_template_option ExpressionTemplates, class OutputIterator>
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OutputIterator export_bits(
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const number<cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>, ExpressionTemplates>& val, OutputIterator out, unsigned chunk_size, bool msv_first = true)
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{
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#ifdef _MSC_VER
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#pragma warning(push)
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#pragma warning(disable:4244)
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#endif
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typedef typename cpp_int_backend<MinBits, MaxBits, SignType, Checked, Allocator>::trivial_tag tag_type;
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if(!val)
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{
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*out = 0;
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++out;
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return out;
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}
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unsigned bitcount = msb(val) + 1;
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unsigned chunks = bitcount / chunk_size;
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if(bitcount % chunk_size)
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++chunks;
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int bit_location = msv_first ? bitcount - chunk_size : 0;
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int bit_step = msv_first ? -static_cast<int>(chunk_size) : chunk_size;
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while(bit_location % bit_step) ++bit_location;
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do
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{
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*out = detail::extract_bits(val.backend(), bit_location, chunk_size, tag_type());
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++out;
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bit_location += bit_step;
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} while((bit_location >= 0) && (bit_location < (int)bitcount));
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return out;
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#ifdef _MSC_VER
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#pragma warning(pop)
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#endif
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}
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}
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}
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#endif // BOOST_MP_CPP_INT_IMPORT_EXPORT_HPP
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