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squeeze BitMask

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This commit is contained in:
Michael Davidsaver
2019-12-13 16:46:06 -08:00
parent 841ef0c048
commit 18d13e81e8
3 changed files with 25 additions and 10 deletions
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src/bitmask.cpp
+18 -3
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@@ -105,9 +105,24 @@ namespace impl {
PVXS_API
void to_wire(Buffer& buf, const BitMask& mask)
{
size_t nbytes = (mask.size() + 7u)/8u; // round up #bits to bytes
size_t nwords = nbytes / 8u;
size_t extra = nbytes % 8u; // trailing single bytes
// ignore trailing zeros
size_t nwords=mask.wsize();
size_t extra = 0u;
while(nwords) {
auto last = mask.word(nwords-1u);
if(last&0xff00000000000000ull) break;
nwords--;
if(last==0) continue;
else if(last&0x00ff000000000000ull) extra=7u;
else if(last&0x0000ff0000000000ull) extra=6u;
else if(last&0x000000ff00000000ull) extra=5u;
else if(last&0x00000000ff000000ull) extra=4u;
else if(last&0x0000000000ff0000ull) extra=3u;
else if(last&0x000000000000ff00ull) extra=2u;
else if(last&0x00000000000000ffull) extra=1u;
break;
}
size_t nbytes = nwords*8u + extra;
to_wire(buf, Size{nbytes});
for(auto i : range(nwords)) {