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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 (
cruft::view<u08 const *> src,
template <typename HashT, typename OutputT>
static
OutputT
find_chunks (
OutputT &&dst,
cruft::view<u08 const*> src,
emory::chunk::params const &p
) {
using hash_type = cruft::hash::buzhash<u64>;
if (src.size () < p.window)
return;
return dst;
using digest_type = hash_type::digest_type ;
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) {
if (likely (hash_state & mask)) {
hash_state = cruft::rotatel (hash_state, 1)
^ cruft::rotatel (u64 (*(cursor - p.window)), p.window)
^ *cursor;
^ cruft::rotatel (u64 (*(cursor - p.window)), p.window)
^ *cursor;
continue;
}
cruft::view<u08 const*> const region { start, cursor };
elements.push_back ({
*dst = {
.offset = {
std::distance (src.begin (), start),
std::distance (src.begin (), cursor)
},
.digest = static_hash {} (region)
});
.digest = HashT {} (region)
};
start = cursor;
break;
@ -62,12 +66,22 @@ map::map (
if (start != src.end ()) {
cruft::view<u08 const*> const region { start, src.end () };
elements.push_back ({
*dst++ = {
.offset = {
std::distance (src.begin (), start),
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);
}