mirror of https://gitee.com/bigwinds/arangodb
127 lines
5.5 KiB
C
127 lines
5.5 KiB
C
#include <stdint.h>
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#define npowers 87
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#define steppowers 8
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#define firstpower -348 /* 10 ^ -348 */
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#define expmax -32
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#define expmin -60
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typedef struct Fp {
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uint64_t frac;
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int exp;
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} Fp;
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static Fp powers_ten[] = {{18054884314459144840U, -1220},
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{13451937075301367670U, -1193},
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{10022474136428063862U, -1166},
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{14934650266808366570U, -1140},
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{11127181549972568877U, -1113},
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{16580792590934885855U, -1087},
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{12353653155963782858U, -1060},
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{18408377700990114895U, -1034},
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{13715310171984221708U, -1007},
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{10218702384817765436U, -980},
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{15227053142812498563U, -954},
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{11345038669416679861U, -927},
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{16905424996341287883U, -901},
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{12595523146049147757U, -874},
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{9384396036005875287U, -847},
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{13983839803942852151U, -821},
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{10418772551374772303U, -794},
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{15525180923007089351U, -768},
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{11567161174868858868U, -741},
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{17236413322193710309U, -715},
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{12842128665889583758U, -688},
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{9568131466127621947U, -661},
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{14257626930069360058U, -635},
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{10622759856335341974U, -608},
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{15829145694278690180U, -582},
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{11793632577567316726U, -555},
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{17573882009934360870U, -529},
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{13093562431584567480U, -502},
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{9755464219737475723U, -475},
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{14536774485912137811U, -449},
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{10830740992659433045U, -422},
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{16139061738043178685U, -396},
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{12024538023802026127U, -369},
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{17917957937422433684U, -343},
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{13349918974505688015U, -316},
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{9946464728195732843U, -289},
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{14821387422376473014U, -263},
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{11042794154864902060U, -236},
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{16455045573212060422U, -210},
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{12259964326927110867U, -183},
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{18268770466636286478U, -157},
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{13611294676837538539U, -130},
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{10141204801825835212U, -103},
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{15111572745182864684U, -77},
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{11258999068426240000U, -50},
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{16777216000000000000U, -24},
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{12500000000000000000U, 3},
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{9313225746154785156U, 30},
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{13877787807814456755U, 56},
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{10339757656912845936U, 83},
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{15407439555097886824U, 109},
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{11479437019748901445U, 136},
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{17105694144590052135U, 162},
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{12744735289059618216U, 189},
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{9495567745759798747U, 216},
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{14149498560666738074U, 242},
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{10542197943230523224U, 269},
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{15709099088952724970U, 295},
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{11704190886730495818U, 322},
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{17440603504673385349U, 348},
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{12994262207056124023U, 375},
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{9681479787123295682U, 402},
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{14426529090290212157U, 428},
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{10748601772107342003U, 455},
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{16016664761464807395U, 481},
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{11933345169920330789U, 508},
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{17782069995880619868U, 534},
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{13248674568444952270U, 561},
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{9871031767461413346U, 588},
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{14708983551653345445U, 614},
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{10959046745042015199U, 641},
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{16330252207878254650U, 667},
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{12166986024289022870U, 694},
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{18130221999122236476U, 720},
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{13508068024458167312U, 747},
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{10064294952495520794U, 774},
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{14996968138956309548U, 800},
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{11173611982879273257U, 827},
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{16649979327439178909U, 853},
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{12405201291620119593U, 880},
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{9242595204427927429U, 907},
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{13772540099066387757U, 933},
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{10261342003245940623U, 960},
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{15290591125556738113U, 986},
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{11392378155556871081U, 1013},
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{16975966327722178521U, 1039},
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{12648080533535911531U, 1066}};
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static Fp find_cachedpow10(int exp, int* k) {
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double const one_log_ten = 0.30102999566398114;
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int approx = static_cast<int>(-(exp + npowers) * one_log_ten);
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int idx = (approx - firstpower) / steppowers;
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while (1) {
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int current = exp + powers_ten[idx].exp + 64;
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if (current < expmin) {
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idx++;
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continue;
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}
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if (current > expmax) {
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idx--;
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continue;
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}
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*k = (firstpower + idx * steppowers);
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return powers_ten[idx];
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}
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}
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