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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include <vespa/vespalib/util/signalhandler.h>
#include <vespa/searchlib/bitcompression/compression.h>
#include <cinttypes>
#include <cassert>
static uint64_t
maxExpGolombVal(uint64_t kValue, uint64_t maxBits)
{
return static_cast<uint64_t>
((UINT64_C(1) << ((maxBits + kValue + 1) / 2)) -
(UINT64_C(1) << kValue));
}
class UniformApp
{
using EC64 = search::bitcompression::EncodeContext64BE;
enum {
MAXK = 30
};
uint64_t _bits[MAXK + 1];
uint64_t _next;
static uint32_t encodeSpace(uint64_t x, uint32_t k) { return EC64::encodeExpGolombSpace(x, k); }
void clearBits();
void reportBits();
public:
int main(int argc, char **argv);
};
void
UniformApp::clearBits()
{
for (unsigned int k = 0; k <= MAXK; ++k)
_bits[k] = 0;
_next = 0;
}
void
UniformApp::reportBits()
{
printf("next=%" PRIu64 " ", _next);
for (unsigned int k = 0; k <= MAXK; ++k)
printf("b[%u]=%" PRIu64 " ",
static_cast<unsigned int>(k),
_bits[k]);
printf("\n");
}
int
UniformApp::main(int, char **)
{
int k, l, m, bestmask, oldbestmask;
printf("Hello world\n");
clearBits();
reportBits();
m = 0;
oldbestmask = 0;
for (;;) {
uint64_t minnext = 0;
int minnextk = 0;
int bestk = 0;
printf("_next=%" PRIu64 "\n", _next);
for (k = 0; k <= MAXK; ++k) {
uint32_t bits = encodeSpace(_next, k); // Current bits
uint64_t next = maxExpGolombVal(k, bits);
assert(encodeSpace(next - 1, k) == bits);
assert(encodeSpace(next, k) > bits);
if (k == 0 || next < minnext) {
minnext = next;
minnextk = k;
}
if (_bits[k] < _bits[bestk])
bestk = k;
printf("k=%d, bits=%d, next=%" PRIu64 "\n", k, bits, next);
}
printf("minnext=%" PRIu64 ", minnextk=%d, bestk=%d\n",
minnext, minnextk, bestk);
for (k = 0; k <= MAXK; ++k) {
uint32_t kbits = encodeSpace(_next, k); // Current bits
l = bestk;
uint32_t lbits = encodeSpace(_next, l); // Current bits
if (_bits[k] > _bits[l] && kbits < lbits) {
uint32_t dbits = lbits - kbits;
uint64_t dsbits = _bits[k] - _bits[l];
uint64_t delt = (dsbits + dbits - 1) / dbits;
if (minnext >= _next + delt) {
minnext = _next + delt;
bestk = k;
}
} else if (_bits[k] == _bits[l] && kbits < lbits) {
minnext = _next + 1;
bestk = k;
}
}
printf("minnext=%" PRIu64 ", minnextk=%d, bestk=%d\n",
minnext, minnextk, bestk);
for (k = 0; k <= MAXK; ++k) {
assert(encodeSpace(_next, k) == encodeSpace(minnext - 1, k));
_bits[k] += (minnext - _next) * encodeSpace(_next, k);
}
_next = minnext;
bestmask = 0;
uint32_t smallk = 0;
for (k = 0; k <= MAXK; ++k) {
if (_bits[k] < _bits[smallk])
smallk = k;
}
for (k = 0; k <= MAXK; ++k)
if (_bits[k] <= _bits[smallk])
bestmask |= (1 << k);
if (bestmask == oldbestmask && _next < (UINT64_C(1) << 30))
continue;
reportBits();
printf("Best k for interval [0..%" PRIu64 ") is", _next);
for (k = 0; k <= MAXK; ++k)
if (_bits[k] <= _bits[smallk])
printf(" %d", k);
printf("\n");
oldbestmask = bestmask;
if (_next >= (UINT64_C(1) << 30))
break;
printf("m iter=%d\n", m);
++m;
if (m >= 10000) {
printf("m breakout\n");
break;
}
}
return 0;
}
int main(int argc, char **argv) {
vespalib::SignalHandler::PIPE.ignore();
UniformApp app;
return app.main(argc, argv);
}
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