1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
|
// This file defines a function to get power-of-10 information about a floating
// point number, used in fpconv.c
// For license, see: fpconv_license.txt
#include <stdint.h>
#define npowers 87
#define steppowers 8
#define firstpower -348 /* 10 ^ -348 */
#define expmax -32
#define expmin -60
typedef struct Fp {
uint64_t frac;
int exp;
} Fp;
static const Fp powers_ten[] = {
{18054884314459144840U, -1220}, {13451937075301367670U, -1193}, {10022474136428063862U, -1166},
{14934650266808366570U, -1140}, {11127181549972568877U, -1113}, {16580792590934885855U, -1087},
{12353653155963782858U, -1060}, {18408377700990114895U, -1034}, {13715310171984221708U, -1007},
{10218702384817765436U, -980}, {15227053142812498563U, -954}, {11345038669416679861U, -927},
{16905424996341287883U, -901}, {12595523146049147757U, -874}, {9384396036005875287U, -847},
{13983839803942852151U, -821}, {10418772551374772303U, -794}, {15525180923007089351U, -768},
{11567161174868858868U, -741}, {17236413322193710309U, -715}, {12842128665889583758U, -688},
{9568131466127621947U, -661}, {14257626930069360058U, -635}, {10622759856335341974U, -608},
{15829145694278690180U, -582}, {11793632577567316726U, -555}, {17573882009934360870U, -529},
{13093562431584567480U, -502}, {9755464219737475723U, -475}, {14536774485912137811U, -449},
{10830740992659433045U, -422}, {16139061738043178685U, -396}, {12024538023802026127U, -369},
{17917957937422433684U, -343}, {13349918974505688015U, -316}, {9946464728195732843U, -289},
{14821387422376473014U, -263}, {11042794154864902060U, -236}, {16455045573212060422U, -210},
{12259964326927110867U, -183}, {18268770466636286478U, -157}, {13611294676837538539U, -130},
{10141204801825835212U, -103}, {15111572745182864684U, -77}, {11258999068426240000U, -50},
{16777216000000000000U, -24}, {12500000000000000000U, 3}, {9313225746154785156U, 30},
{13877787807814456755U, 56}, {10339757656912845936U, 83}, {15407439555097886824U, 109},
{11479437019748901445U, 136}, {17105694144590052135U, 162}, {12744735289059618216U, 189},
{9495567745759798747U, 216}, {14149498560666738074U, 242}, {10542197943230523224U, 269},
{15709099088952724970U, 295}, {11704190886730495818U, 322}, {17440603504673385349U, 348},
{12994262207056124023U, 375}, {9681479787123295682U, 402}, {14426529090290212157U, 428},
{10748601772107342003U, 455}, {16016664761464807395U, 481}, {11933345169920330789U, 508},
{17782069995880619868U, 534}, {13248674568444952270U, 561}, {9871031767461413346U, 588},
{14708983551653345445U, 614}, {10959046745042015199U, 641}, {16330252207878254650U, 667},
{12166986024289022870U, 694}, {18130221999122236476U, 720}, {13508068024458167312U, 747},
{10064294952495520794U, 774}, {14996968138956309548U, 800}, {11173611982879273257U, 827},
{16649979327439178909U, 853}, {12405201291620119593U, 880}, {9242595204427927429U, 907},
{13772540099066387757U, 933}, {10261342003245940623U, 960}, {15290591125556738113U, 986},
{11392378155556871081U, 1013}, {16975966327722178521U, 1039}, {12648080533535911531U, 1066}};
static Fp find_cachedpow10(int exp, int *k) {
const double one_log_ten = 0.30102999566398114;
int approx = -(exp + npowers) * one_log_ten;
int idx = (approx - firstpower) / steppowers;
while (1) {
int current = exp + powers_ten[idx].exp + 64;
if (current < expmin) {
idx++;
continue;
}
if (current > expmax) {
idx--;
continue;
}
*k = (firstpower + idx * steppowers);
return powers_ten[idx];
}
}
|
