// Copyright (c) 2017, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Adapted from Python code by Sarang Noether
#include "misc_log_ex.h"
#include "common/perf_timer.h"
extern "C"
{
#include "crypto/crypto-ops.h"
}
#include "common/aligned.h"
#include "rctOps.h"
#include "multiexp.h"
#undef MONERO_DEFAULT_LOG_CATEGORY
#define MONERO_DEFAULT_LOG_CATEGORY "multiexp"
//#define MULTIEXP_PERF(x) x
#define MULTIEXP_PERF(x)
#define RAW_MEMORY_BLOCK
//#define ALTERNATE_LAYOUT
//#define TRACK_STRAUS_ZERO_IDENTITY
// per points us for N/B points (B point bands)
// raw alt 128/192 4096/192 4096/4096
// 0 0 52.6 71 71.2
// 0 1 53.2 72.2 72.4
// 1 0 52.7 67 67.1
// 1 1 52.8 70.4 70.2
// Pippenger:
// 1 2 3 4 5 6 7 8 9 bestN
// 2 555 598 621 804 1038 1733 2486 5020 8304 1
// 4 783 747 800 1006 1428 2132 3285 5185 9806 2
// 8 1174 1071 1095 1286 1640 2398 3869 6378 12080 2
// 16 2279 1874 1745 1739 2144 2831 4209 6964 12007 4
// 32 3910 3706 2588 2477 2782 3467 4856 7489 12618 4
// 64 7184 5429 4710 4368 4010 4672 6027 8559 13684 5
// 128 14097 10574 8452 7297 6841 6718 8615 10580 15641 6
// 256 27715 20800 16000 13550 11875 11400 11505 14090 18460 6
// 512 55100 41250 31740 26570 22030 19830 20760 21380 25215 6
// 1024 111520 79000 61080 49720 43080 38320 37600 35040 36750 8
// 2048 219480 162680 122120 102080 83760 70360 66600 63920 66160 8
// 4096 453320 323080 247240 210200 180040 150240 132440 114920 110560 9
// 2 4 8 16 32 64 128 256 512 1024 2048 4096
// Bos Coster 858 994 1316 1949 3183 5512 9865 17830 33485 63160 124280 246320
// Straus 226 341 548 980 1870 3538 7039 14490 29020 57200 118640 233640
// Straus/cached 226 315 485 785 1514 2858 5753 11065 22970 45120 98880 194840
// Pippenger 555 747 1071 1739 2477 4010 6718 11400 19830 35040 63920 110560
// Best/cached Straus Straus Straus Straus Straus Straus Straus Straus Pip Pip Pip Pip
// Best/uncached Straus Straus Straus Straus Straus Straus Pip Pip Pip Pip Pip Pip
namespace rct
{
static inline bool operator<(const rct::key &k0, const rct::key&k1)
{
for (int n = 31; n >= 0; --n)
{
if (k0.bytes[n] < k1.bytes[n])
return true;
if (k0.bytes[n] > k1.bytes[n])
return false;
}
return false;
}
static inline rct::key div2(const rct::key &k)
{
rct::key res;
int carry = 0;
for (int n = 31; n >= 0; --n)
{
int new_carry = (k.bytes[n] & 1) << 7;
res.bytes[n] = k.bytes[n] / 2 + carry;
carry = new_carry;
}
return res;
}
static inline rct::key pow2(size_t n)
{
CHECK_AND_ASSERT_THROW_MES(n < 256, "Invalid pow2 argument");
rct::key res = rct::zero();
res[n >> 3] |= 1<<(n&7);
return res;
}
static inline int test(const rct::key &k, size_t n)
{
if (n >= 256) return 0;
return k[n >> 3] & (1 << (n & 7));
}
static inline void add(ge_p3 &p3, const ge_cached &other)
{
ge_p1p1 p1;
ge_add(&p1, &p3, &other);
ge_p1p1_to_p3(&p3, &p1);
}
static inline void add(ge_p3 &p3, const ge_p3 &other)
{
ge_cached cached;
ge_p3_to_cached(&cached, &other);
add(p3, cached);
}
rct::key bos_coster_heap_conv(std::vector<MultiexpData> data)
{
MULTIEXP_PERF(PERF_TIMER_START_UNIT(bos_coster, 1000000));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(setup, 1000000));
size_t points = data.size();
CHECK_AND_ASSERT_THROW_MES(points > 1, "Not enough points");
std::vector<size_t> heap(points);
for (size_t n = 0; n < points; ++n)
heap[n] = n;
auto Comp = [&](size_t e0, size_t e1) { return data[e0].scalar < data[e1].scalar; };
std::make_heap(heap.begin(), heap.end(), Comp);
MULTIEXP_PERF(PERF_TIMER_STOP(setup));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(loop, 1000000));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(pop, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(pop));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(add, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(add));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(sub, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(sub));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(push, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(push));
while (heap.size() > 1)
{
MULTIEXP_PERF(PERF_TIMER_RESUME(pop));
std::pop_heap(heap.begin(), heap.end(), Comp);
size_t index1 = heap.back();
heap.pop_back();
std::pop_heap(heap.begin(), heap.end(), Comp);
size_t index2 = heap.back();
heap.pop_back();
MULTIEXP_PERF(PERF_TIMER_PAUSE(pop));
MULTIEXP_PERF(PERF_TIMER_RESUME(add));
ge_cached cached;
ge_p3_to_cached(&cached, &data[index1].point);
ge_p1p1 p1;
ge_add(&p1, &data[index2].point, &cached);
ge_p1p1_to_p3(&data[index2].point, &p1);
MULTIEXP_PERF(PERF_TIMER_PAUSE(add));
MULTIEXP_PERF(PERF_TIMER_RESUME(sub));
sc_sub(data[index1].scalar.bytes, data[index1].scalar.bytes, data[index2].scalar.bytes);
MULTIEXP_PERF(PERF_TIMER_PAUSE(sub));
MULTIEXP_PERF(PERF_TIMER_RESUME(push));
if (!(data[index1].scalar == rct::zero()))
{
heap.push_back(index1);
std::push_heap(heap.begin(), heap.end(), Comp);
}
heap.push_back(index2);
std::push_heap(heap.begin(), heap.end(), Comp);
MULTIEXP_PERF(PERF_TIMER_PAUSE(push));
}
MULTIEXP_PERF(PERF_TIMER_STOP(push));
MULTIEXP_PERF(PERF_TIMER_STOP(sub));
MULTIEXP_PERF(PERF_TIMER_STOP(add));
MULTIEXP_PERF(PERF_TIMER_STOP(pop));
MULTIEXP_PERF(PERF_TIMER_STOP(loop));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(end, 1000000));
//return rct::scalarmultKey(data[index1].point, data[index1].scalar);
std::pop_heap(heap.begin(), heap.end(), Comp);
size_t index1 = heap.back();
heap.pop_back();
ge_p2 p2;
ge_scalarmult(&p2, data[index1].scalar.bytes, &data[index1].point);
rct::key res;
ge_tobytes(res.bytes, &p2);
return res;
}
rct::key bos_coster_heap_conv_robust(std::vector<MultiexpData> data)
{
MULTIEXP_PERF(PERF_TIMER_START_UNIT(bos_coster, 1000000));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(setup, 1000000));
size_t points = data.size();
CHECK_AND_ASSERT_THROW_MES(points > 0, "Not enough points");
std::vector<size_t> heap;
heap.reserve(points);
for (size_t n = 0; n < points; ++n)
{
if (!(data[n].scalar == rct::zero()) && memcmp(&data[n].point, &ge_p3_identity, sizeof(ge_p3)))
heap.push_back(n);
}
points = heap.size();
if (points == 0)
return rct::identity();
if (points < 2)
{
ge_p2 p2;
ge_scalarmult(&p2, data[0].scalar.bytes, &data[0].point);
rct::key res;
ge_tobytes(res.bytes, &p2);
return res;
}
auto Comp = [&](size_t e0, size_t e1) { return data[e0].scalar < data[e1].scalar; };
std::make_heap(heap.begin(), heap.end(), Comp);
MULTIEXP_PERF(PERF_TIMER_STOP(setup));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(loop, 1000000));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(pop, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(pop));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(div, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(div));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(add, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(add));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(sub, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(sub));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(push, 1000000)); MULTIEXP_PERF(PERF_TIMER_PAUSE(push));
while (heap.size() > 1)
{
MULTIEXP_PERF(PERF_TIMER_RESUME(pop));
std::pop_heap(heap.begin(), heap.end(), Comp);
size_t index1 = heap.back();
heap.pop_back();
std::pop_heap(heap.begin(), heap.end(), Comp);
size_t index2 = heap.back();
heap.pop_back();
MULTIEXP_PERF(PERF_TIMER_PAUSE(pop));
ge_cached cached;
ge_p1p1 p1;
ge_p2 p2;
MULTIEXP_PERF(PERF_TIMER_RESUME(div));
while (1)
{
rct::key s1_2 = div2(data[index1].scalar);
if (!(data[index2].scalar < s1_2))
break;
if (data[index1].scalar.bytes[0] & 1)
{
data.resize(data.size()+1);
data.back().scalar = rct::identity();
data.back().point = data[index1].point;
heap.push_back(data.size() - 1);
std::push_heap(heap.begin(), heap.end(), Comp);
}
data[index1].scalar = div2(data[index1].scalar);
ge_p3_to_p2(&p2, &data[index1].point);
ge_p2_dbl(&p1, &p2);
ge_p1p1_to_p3(&data[index1].point, &p1);
}
MULTIEXP_PERF(PERF_TIMER_PAUSE(div));
MULTIEXP_PERF(PERF_TIMER_RESUME(add));
ge_p3_to_cached(&cached, &data[index1].point);
ge_add(&p1, &data[index2].point, &cached);
ge_p1p1_to_p3(&data[index2].point, &p1);
MULTIEXP_PERF(PERF_TIMER_PAUSE(add));
MULTIEXP_PERF(PERF_TIMER_RESUME(sub));
sc_sub(data[index1].scalar.bytes, data[index1].scalar.bytes, data[index2].scalar.bytes);
MULTIEXP_PERF(PERF_TIMER_PAUSE(sub));
MULTIEXP_PERF(PERF_TIMER_RESUME(push));
if (!(data[index1].scalar == rct::zero()))
{
heap.push_back(index1);
std::push_heap(heap.begin(), heap.end(), Comp);
}
heap.push_back(index2);
std::push_heap(heap.begin(), heap.end(), Comp);
MULTIEXP_PERF(PERF_TIMER_PAUSE(push));
}
MULTIEXP_PERF(PERF_TIMER_STOP(push));
MULTIEXP_PERF(PERF_TIMER_STOP(sub));
MULTIEXP_PERF(PERF_TIMER_STOP(add));
MULTIEXP_PERF(PERF_TIMER_STOP(pop));
MULTIEXP_PERF(PERF_TIMER_STOP(loop));
MULTIEXP_PERF(PERF_TIMER_START_UNIT(end, 1000000));
//return rct::scalarmultKey(data[index1].point, data[index1].scalar);
std::pop_heap(heap.begin(), heap.end(), Comp);
size_t index1 = heap.back();
heap.pop_back();
ge_p2 p2;
ge_scalarmult(&p2, data[index1].scalar.bytes, &data[index1].point);
rct::key res;
ge_tobytes(res.bytes, &p2);
return res;
}
static constexpr unsigned int STRAUS_C = 4;
struct straus_cached_data
{
#ifdef RAW_MEMORY_BLOCK
size_t size;
ge_cached *multiples;
straus_cached_data(): size(0), multiples(NULL) {}
~straus_cached_data() { aligned_free(multiples); }
#else
std::vector<std::vector<ge_cached>> multiples;
#endif
};
#ifdef RAW_MEMORY_BLOCK
#ifdef ALTERNATE_LAYOUT
#define CACHE_OFFSET(cache,point,digit) cache->multiples[(point)*((1<<STRAUS_C)-1)+((digit)-1)]
#else
#define CACHE_OFFSET(cache,point,digit) cache->multiples[(point)+cache->size*((digit)-1)]
#endif
#else
#ifdef ALTERNATE_LAYOUT
#define CACHE_OFFSET(cache,point,digit) local_cache->multiples[j][digit-1]
#else
#define CACHE_OFFSET(cache,point,digit) local_cache->multiples[digit][j]
#endif
#endif
std::shared_ptr<straus_cached_data> straus_init_cache(const std::vector<MultiexpData> &data, size_t N)
{
MULTIEXP_PERF(PERF_TIMER_START_UNIT(multiples, 1000000));
if (N == 0)
N = data.size();
CHECK_AND_ASSERT_THROW_MES(N <= data.size(), "Bad cache base data");
ge_cached cached;
ge_p1p1 p1;
ge_p3 p3;
std::shared_ptr<straus_cached_data> cache(new straus_cached_data());
#ifdef RAW_MEMORY_BLOCK
const size_t offset = cache->size;
cache->multiples = (ge_cached*)aligned_realloc(cache->multiples, sizeof(ge_cached) * ((1<<STRAUS_C)-1) * std::max(offset, N), 4096);
CHECK_AND_ASSERT_THROW_MES(cache->multiples, "Out of memory");
cache->size = N;
for (size_t j=offset;j<N;++j)
{
ge_p3_to_cached(&CACHE_OFFSET(cache, j, 1), &data[j].point);
for (size_t i=2;i<1<<STRAUS_C;++i)
{
ge_add(&p1, &data[j].point, &CACHE_OFFSET(cache, j, i-1));
ge_p1p1_to_p3(&p3, &p1);
ge_p3_to_cached(&CACHE_OFFSET(cache, j, i), &p3);
}
}
#else
#ifdef ALTERNATE_LAYOUT
const size_t offset = cache->multiples.size();
cache->multiples.resize(std::max(offset, N));
for (size_t i = offset; i < N; ++i)
{
cache->multiples[i].resize((1<<STRAUS_C)-1);
ge_p3_to_cached(&cache->multiples[i][0], &data[i].point);
for (size_t j=2;j<1<<STRAUS_C;++j)
{
ge_add(&p1, &data[i].point, &cache->multiples[i][j-2]);
ge_p1p1_to_p3(&p3, &p1);
ge_p3_to_cached(&cache->multiples[i][j-1], &p3);
}
}
#else
cache->multiples.resize(1<<STRAUS_C);
size_t offset = cache->multiples[1].size();
cache->multiples[1].resize(std::max(offset, N));
for (size_t i = offset; i < N; ++i)
ge_p3_to_cached(&cache->multiples[1][i], &data[i].point);
for (size_t i=2;i<1<<STRAUS_C;++i)
cache->multiples[i].resize(std::max(offset, N));
for (size_t j=offset;j<N;++j)
{
for (size_t i=2;i<1<<STRAUS_C;++i)
{
ge_add(&p1, &data[j].point, &cache->multiples[i-1][j]);
ge_p1p1_to_p3(&p3, &p1);
ge_p3_to_cached(&cache->multiples[i][j], &p3);
}
}
#endif
#endif
MULTIEXP_PERF(PERF_TIMER_STOP(multiples));
return cache;
}
size_t straus_get_cache_size(const std::shared_ptr<straus_cached_data> &cache)
{
size_t sz = 0;
#ifdef RAW_MEMORY_BLOCK
sz += cache->size * sizeof(ge_cached) * ((1<<STRAUS_C)-1);
#else
for (const auto &e0: cache->multiples)
sz += e0.size() * sizeof(ge_cached);
#endif
return sz;
}
rct::key straus(const std::vector<MultiexpData> &data, const std::shared_ptr<straus_cached_data> &cache, size_t STEP)
{
CHECK_AND_ASSERT_THROW_MES(cache == NULL || cache->size >= data.size(), "Cache is too small");
MULTIEXP_PERF(PERF_TIMER_UNIT(straus, 1000000));
bool HiGi = cache != NULL;
STEP = STEP ? STEP : 192;
MULTIEXP_PERF(PERF_TIMER_START_UNIT(setup, 1000000));
static constexpr unsigned int mask = (1<<STRAUS_C)-1;
std::shared_ptr<straus_cached_data> local_cache = cache == NULL ? straus_init_cache(data) : cache;
ge_cached cached;
ge_p1p1 p1;
ge_p3 p3;
#ifdef TRACK_STRAUS_ZERO_IDENTITY
MULTIEXP_PERF(PERF_TIMER_START_UNIT(skip, 1000000));
std::vector<uint8_t> skip(data.size());
for (size_t i = 0; i < data.size(); ++i)
skip[i] = data[i].scalar == rct::zero() || !memcmp(&data[i].point, &ge_p3_identity, sizeof(ge_p3));
MULTIEXP_PERF(PERF_TIMER_STOP(skip));
#endif
MULTIEXP_PERF(PERF_TIMER_START_UNIT(digits, 1000000));
std::unique_ptr<uint8_t[]> digits{new uint8_t[256 * data.size()]};
for (size_t j = 0; j < data.size(); ++j)
{
unsigned char bytes33[33];
memcpy(bytes33, data[j].scalar.bytes, 32);
bytes33[32] = 0;
const unsigned char *bytes = bytes33;
#if 1
static_assert(STRAUS_C == 4, "optimized version needs STRAUS_C == 4");
unsigned int i;
for (i = 0; i < 256; i += 8, bytes++)
{
digits[j*256+i] = bytes[0] & 0xf;
digits[j*256+i+1] = (bytes[0] >> 1) & 0xf;
digits[j*256+i+2] = (bytes[0] >> 2) & 0xf;
digits[j*256+i+3] = (bytes[0] >> 3) & 0xf;
digits[j*256+i+4] = ((bytes[0] >> 4) | (bytes[1]<<4)) & 0xf;
digits[j*256+i+5] = ((bytes[0] >> 5) | (bytes[1]<<3)) & 0xf;
digits[j*256+i+6] = ((bytes[0] >> 6) | (bytes[1]<<2)) & 0xf;
digits[j*256+i+7] = ((bytes[0] >> 7) | (bytes[1]<<1)) & 0xf;
}
#elif 1
for (size_t i = 0; i < 256; ++i)
digits[j*256+i] = ((bytes[i>>3] | (bytes[(i>>3)+1]<<8)) >> (i&7)) & mask;
#else
rct::key shifted = data[j].scalar;
for (size_t i = 0; i < 256; ++i)
{
digits[j*256+i] = shifted.bytes[0] & 0xf;
shifted = div2(shifted, (256-i)>>3);
}
#endif
}
MULTIEXP_PERF(PERF_TIMER_STOP(digits));
rct::key maxscalar = rct::zero();
for (size_t i = 0; i < data.size(); ++i)
if (maxscalar < data[i].scalar)
maxscalar = data[i].scalar;
size_t start_i = 0;
while (start_i < 256 && !(maxscalar < pow2(start_i)))
start_i += STRAUS_C;
MULTIEXP_PERF(PERF_TIMER_STOP(setup));
ge_p3 res_p3 = ge_p3_identity;
for (size_t start_offset = 0; start_offset < data.size(); start_offset += STEP)
{
const size_t num_points = std::min(data.size() - start_offset, STEP);
ge_p3 band_p3 = ge_p3_identity;
size_t i = start_i;
if (!(i < STRAUS_C))
goto skipfirst;
while (!(i < STRAUS_C))
{
ge_p2 p2;
ge_p3_to_p2(&p2, &band_p3);
for (size_t j = 0; j < STRAUS_C; ++j)
{
ge_p2_dbl(&p1, &p2);
if (j == STRAUS_C - 1)
ge_p1p1_to_p3(&band_p3, &p1);
else
ge_p1p1_to_p2(&p2, &p1);
}
skipfirst:
i -= STRAUS_C;
for (size_t j = start_offset; j < start_offset + num_points; ++j)
{
#ifdef TRACK_STRAUS_ZERO_IDENTITY
if (skip[j])
continue;
#endif
const uint8_t digit = digits[j*256+i];
if (digit)
{
ge_add(&p1, &band_p3, &CACHE_OFFSET(local_cache, j, digit));
ge_p1p1_to_p3(&band_p3, &p1);
}
}
}
ge_p3_to_cached(&cached, &band_p3);
ge_add(&p1, &res_p3, &cached);
ge_p1p1_to_p3(&res_p3, &p1);
}
rct::key res;
ge_p3_tobytes(res.bytes, &res_p3);
return res;
}
size_t get_pippenger_c(size_t N)
{
// uncached: 2:1, 4:2, 8:2, 16:3, 32:4, 64:4, 128:5, 256:6, 512:7, 1024:7, 2048:8, 4096:9
// cached: 2:1, 4:2, 8:2, 16:3, 32:4, 64:4, 128:5, 256:6, 512:7, 1024:7, 2048:8, 4096:9
if (N <= 2) return 1;
if (N <= 8) return 2;
if (N <= 16) return 3;
if (N <= 64) return 4;
if (N <= 128) return 5;
if (N <= 256) return 6;
if (N <= 1024) return 7;
if (N <= 2048) return 8;
return 9;
}
struct pippenger_cached_data
{
size_t size;
ge_cached *cached;
pippenger_cached_data(): size(0), cached(NULL) {}
~pippenger_cached_data() { aligned_free(cached); }
};
std::shared_ptr<pippenger_cached_data> pippenger_init_cache(const std::vector<MultiexpData> &data, size_t N)
{
MULTIEXP_PERF(PERF_TIMER_START_UNIT(pippenger_init_cache, 1000000));
if (N == 0)
N = data.size();
CHECK_AND_ASSERT_THROW_MES(N <= data.size(), "Bad cache base data");
ge_cached cached;
std::shared_ptr<pippenger_cached_data> cache(new pippenger_cached_data());
cache->size = N;
cache->cached = (ge_cached*)aligned_realloc(cache->cached, N * sizeof(ge_cached), 4096);
CHECK_AND_ASSERT_THROW_MES(cache->cached, "Out of memory");
for (size_t i = 0; i < N; ++i)
ge_p3_to_cached(&cache->cached[i], &data[i].point);
MULTIEXP_PERF(PERF_TIMER_STOP(pippenger_init_cache));
return cache;
}
size_t pippenger_get_cache_size(const std::shared_ptr<pippenger_cached_data> &cache)
{
return cache->size * sizeof(*cache->cached);
}
rct::key pippenger(const std::vector<MultiexpData> &data, const std::shared_ptr<pippenger_cached_data> &cache, size_t c)
{
CHECK_AND_ASSERT_THROW_MES(cache == NULL || cache->size >= data.size(), "Cache is too small");
if (c == 0)
c = get_pippenger_c(data.size());
CHECK_AND_ASSERT_THROW_MES(c <= 9, "c is too large");
ge_p3 result = ge_p3_identity;
std::unique_ptr<ge_p3[]> buckets{new ge_p3[1<<c]};
std::shared_ptr<pippenger_cached_data> local_cache = cache == NULL ? pippenger_init_cache(data) : cache;
rct::key maxscalar = rct::zero();
for (size_t i = 0; i < data.size(); ++i)
{
if (maxscalar < data[i].scalar)
maxscalar = data[i].scalar;
}
size_t groups = 0;
while (groups < 256 && pow2(groups) < maxscalar)
++groups;
groups = (groups + c - 1) / c;
for (size_t k = groups; k-- > 0; )
{
if (memcmp(&result, &ge_p3_identity, sizeof(ge_p3)))
{
ge_p2 p2;
ge_p3_to_p2(&p2, &result);
for (size_t i = 0; i < c; ++i)
{
ge_p1p1 p1;
ge_p2_dbl(&p1, &p2);
if (i == c - 1)
ge_p1p1_to_p3(&result, &p1);
else
ge_p1p1_to_p2(&p2, &p1);
}
}
for (size_t i = 0; i < (1u<<c); ++i)
buckets[i] = ge_p3_identity;
// partition scalars into buckets
for (size_t i = 0; i < data.size(); ++i)
{
unsigned int bucket = 0;
for (size_t j = 0; j < c; ++j)
if (test(data[i].scalar, k*c+j))
bucket |= 1<<j;
if (bucket == 0)
continue;
CHECK_AND_ASSERT_THROW_MES(bucket < (1u<<c), "bucket overflow");
if (memcmp(&buckets[bucket], &ge_p3_identity, sizeof(ge_p3)))
{
add(buckets[bucket], local_cache->cached[i]);
}
else
buckets[bucket] = data[i].point;
}
// sum the buckets
ge_p3 pail = ge_p3_identity;
for (size_t i = (1<<c)-1; i > 0; --i)
{
if (memcmp(&buckets[i], &ge_p3_identity, sizeof(ge_p3)))
add(pail, buckets[i]);
if (memcmp(&pail, &ge_p3_identity, sizeof(ge_p3)))
add(result, pail);
}
}
rct::key res;
ge_p3_tobytes(res.bytes, &result);
return res;
}
}
