diff options
Diffstat (limited to 'src/ringct/multiexp.cc')
| -rw-r--r-- | src/ringct/multiexp.cc | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/src/ringct/multiexp.cc b/src/ringct/multiexp.cc index 52c6feb71..fd2d1cbd7 100644 --- a/src/ringct/multiexp.cc +++ b/src/ringct/multiexp.cc @@ -55,6 +55,30 @@ extern "C" // 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 { @@ -91,6 +115,26 @@ static inline rct::key pow2(size_t n) 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)); @@ -487,4 +531,93 @@ skipfirst: return res; } +size_t get_pippenger_c(size_t N) +{ +// 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; +} + +rct::key pippenger(const std::vector<MultiexpData> &data, size_t c) +{ + 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::unique_ptr<ge_cached[]> cached_points{new ge_cached[data.size()]}; + + for (size_t i = 0; i < data.size(); ++i) + { + ge_p3_to_cached(&cached_points[i], &data[i].point); + } + + 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], cached_points[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; +} + } |