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emory/chunk/map: move chunking to a free function

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This commit is contained in:
Danny Robson 2020-12-06 09:17:50 +10:00
parent 66ec824b44
commit db6c4f54a2
1 changed files with 25 additions and 11 deletions
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36
emory/chunk/map.cpp
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@ -16,13 +16,17 @@ using emory::chunk::map;
/////////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////
map::map ( template <typename HashT, typename OutputT>
cruft::view<u08 const *> src, static
OutputT
find_chunks (
OutputT &&dst,
cruft::view<u08 const*> src,
emory::chunk::params const &p emory::chunk::params const &p
) { ) {
using hash_type = cruft::hash::buzhash<u64>; using hash_type = cruft::hash::buzhash<u64>;
if (src.size () < p.window) if (src.size () < p.window)
return; return dst;
using digest_type = hash_type::digest_type ; using digest_type = hash_type::digest_type ;
digest_type const mask = ~digest_type (0) >> (sizeof (digest_type) * 8 - p.bits); digest_type const mask = ~digest_type (0) >> (sizeof (digest_type) * 8 - p.bits);
@ -39,20 +43,20 @@ map::map (
for ( ; cursor < src.end () - p.window; ++cursor) { for ( ; cursor < src.end () - p.window; ++cursor) {
if (likely (hash_state & mask)) { if (likely (hash_state & mask)) {
hash_state = cruft::rotatel (hash_state, 1) hash_state = cruft::rotatel (hash_state, 1)
^ cruft::rotatel (u64 (*(cursor - p.window)), p.window) ^ cruft::rotatel (u64 (*(cursor - p.window)), p.window)
^ *cursor; ^ *cursor;
continue; continue;
} }
cruft::view<u08 const*> const region { start, cursor }; cruft::view<u08 const*> const region { start, cursor };
elements.push_back ({ *dst = {
.offset = { .offset = {
std::distance (src.begin (), start), std::distance (src.begin (), start),
std::distance (src.begin (), cursor) std::distance (src.begin (), cursor)
}, },
.digest = static_hash {} (region) .digest = HashT {} (region)
}); };
start = cursor; start = cursor;
break; break;
@ -62,12 +66,22 @@ map::map (
if (start != src.end ()) { if (start != src.end ()) {
cruft::view<u08 const*> const region { start, src.end () }; cruft::view<u08 const*> const region { start, src.end () };
elements.push_back ({ *dst++ = {
.offset = { .offset = {
std::distance (src.begin (), start), std::distance (src.begin (), start),
std::distance (src.begin (), src.end ()) std::distance (src.begin (), src.end ())
}, },
.digest = static_hash {} (region) .digest = HashT {} (region)
}); };
} }
return dst;
}
///////////////////////////////////////////////////////////////////////////////
map::map (
cruft::view<u08 const *> src,
emory::chunk::params const &p
) {
::find_chunks<static_hash> (std::back_inserter (elements), src, p);
} }