mirror of
https://github.com/moses-smt/mosesdecoder.git
synced 2024-11-10 10:59:21 +03:00
98 lines
3.6 KiB
C++
98 lines
3.6 KiB
C++
#include "lm/bhiksha.hh"
|
|
#include "lm/config.hh"
|
|
|
|
#include <limits>
|
|
|
|
namespace lm {
|
|
namespace ngram {
|
|
namespace trie {
|
|
|
|
DontBhiksha::DontBhiksha(const void * /*base*/, uint64_t /*max_offset*/, uint64_t max_next, const Config &/*config*/) :
|
|
next_(util::BitsMask::ByMax(max_next)) {}
|
|
|
|
const uint8_t kArrayBhikshaVersion = 0;
|
|
|
|
void ArrayBhiksha::UpdateConfigFromBinary(FD fd, Config &config) {
|
|
uint8_t version;
|
|
uint8_t configured_bits;
|
|
#ifdef WIN32
|
|
#else
|
|
if (read(fd, &version, 1) != 1 || read(fd, &configured_bits, 1) != 1) {
|
|
UTIL_THROW(util::ErrnoException, "Could not read from binary file");
|
|
}
|
|
#endif
|
|
|
|
if (version != kArrayBhikshaVersion) UTIL_THROW(FormatLoadException, "This file has sorted array compression version " << (unsigned) version << " but the code expects version " << (unsigned)kArrayBhikshaVersion);
|
|
config.pointer_bhiksha_bits = configured_bits;
|
|
}
|
|
|
|
namespace {
|
|
|
|
// Find argmin_{chopped \in [0, RequiredBits(max_next)]} ChoppedDelta(max_offset)
|
|
uint8_t ChopBits(uint64_t max_offset, uint64_t max_next, const Config &config) {
|
|
uint8_t required = util::RequiredBits(max_next);
|
|
uint8_t best_chop = 0;
|
|
int64_t lowest_change = std::numeric_limits<int64_t>::max();
|
|
// There are probably faster ways but I don't care because this is only done once per order at construction time.
|
|
for (uint8_t chop = 0; chop <= std::min(required, config.pointer_bhiksha_bits); ++chop) {
|
|
int64_t change = (max_next >> (required - chop)) * 64 /* table cost in bits */
|
|
- max_offset * static_cast<int64_t>(chop); /* savings in bits*/
|
|
if (change < lowest_change) {
|
|
lowest_change = change;
|
|
best_chop = chop;
|
|
}
|
|
}
|
|
return best_chop;
|
|
}
|
|
|
|
std::size_t ArrayCount(uint64_t max_offset, uint64_t max_next, const Config &config) {
|
|
uint8_t required = util::RequiredBits(max_next);
|
|
uint8_t chopping = ChopBits(max_offset, max_next, config);
|
|
return (max_next >> (required - chopping)) + 1 /* we store 0 too */;
|
|
}
|
|
} // namespace
|
|
|
|
std::size_t ArrayBhiksha::Size(uint64_t max_offset, uint64_t max_next, const Config &config) {
|
|
return sizeof(uint64_t) * (1 /* header */ + ArrayCount(max_offset, max_next, config)) + 7 /* 8-byte alignment */;
|
|
}
|
|
|
|
uint8_t ArrayBhiksha::InlineBits(uint64_t max_offset, uint64_t max_next, const Config &config) {
|
|
return util::RequiredBits(max_next) - ChopBits(max_offset, max_next, config);
|
|
}
|
|
|
|
namespace {
|
|
|
|
void *AlignTo8(void *from) {
|
|
uint8_t *val = reinterpret_cast<uint8_t*>(from);
|
|
std::size_t remainder = reinterpret_cast<std::size_t>(val) & 7;
|
|
if (!remainder) return val;
|
|
return val + 8 - remainder;
|
|
}
|
|
|
|
} // namespace
|
|
|
|
ArrayBhiksha::ArrayBhiksha(void *base, uint64_t max_offset, uint64_t max_next, const Config &config)
|
|
: next_inline_(util::BitsMask::ByBits(InlineBits(max_offset, max_next, config))),
|
|
offset_begin_(reinterpret_cast<const uint64_t*>(AlignTo8(base)) + 1 /* 8-byte header */),
|
|
offset_end_(offset_begin_ + ArrayCount(max_offset, max_next, config)),
|
|
write_to_(reinterpret_cast<uint64_t*>(AlignTo8(base)) + 1 /* 8-byte header */ + 1 /* first entry is 0 */),
|
|
original_base_(base) {}
|
|
|
|
void ArrayBhiksha::FinishedLoading(const Config &config) {
|
|
// *offset_begin_ = 0 but without a const_cast.
|
|
*(write_to_ - (write_to_ - offset_begin_)) = 0;
|
|
|
|
if (write_to_ != offset_end_) UTIL_THROW(util::Exception, "Did not get all the array entries that were expected.");
|
|
|
|
uint8_t *head_write = reinterpret_cast<uint8_t*>(original_base_);
|
|
*(head_write++) = kArrayBhikshaVersion;
|
|
*(head_write++) = config.pointer_bhiksha_bits;
|
|
}
|
|
|
|
void ArrayBhiksha::LoadedBinary() {
|
|
}
|
|
|
|
} // namespace trie
|
|
} // namespace ngram
|
|
} // namespace lm
|