Last change
on this file since 351 was 337, checked in by coas-nagasima, 6 years ago |
ASP3版ECNLを追加
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Property svn:eol-style
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native
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Property svn:mime-type
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text/x-csrc;charset=UTF-8
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File size:
1.2 KB
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1 | #include <math.h>
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2 | #include <stdint.h>
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3 |
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4 | double fmod(double x, double y)
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5 | {
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6 | union {double f; uint64_t i;} ux = {x}, uy = {y};
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7 | int ex = ux.i>>52 & 0x7ff;
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8 | int ey = uy.i>>52 & 0x7ff;
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9 | int sx = ux.i>>63;
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10 | uint64_t i;
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11 |
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12 | /* in the followings uxi should be ux.i, but then gcc wrongly adds */
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13 | /* float load/store to inner loops ruining performance and code size */
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14 | uint64_t uxi = ux.i;
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15 |
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16 | if (uy.i<<1 == 0 || isnan(y) || ex == 0x7ff)
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17 | return (x*y)/(x*y);
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18 | if (uxi<<1 <= uy.i<<1) {
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19 | if (uxi<<1 == uy.i<<1)
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20 | return 0*x;
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21 | return x;
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22 | }
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23 |
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24 | /* normalize x and y */
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25 | if (!ex) {
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26 | for (i = uxi<<12; i>>63 == 0; ex--, i <<= 1);
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27 | uxi <<= -ex + 1;
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28 | } else {
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29 | uxi &= -1ULL >> 12;
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30 | uxi |= 1ULL << 52;
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31 | }
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32 | if (!ey) {
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33 | for (i = uy.i<<12; i>>63 == 0; ey--, i <<= 1);
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34 | uy.i <<= -ey + 1;
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35 | } else {
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36 | uy.i &= -1ULL >> 12;
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37 | uy.i |= 1ULL << 52;
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38 | }
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39 |
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40 | /* x mod y */
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41 | for (; ex > ey; ex--) {
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42 | i = uxi - uy.i;
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43 | if (i >> 63 == 0) {
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44 | if (i == 0)
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45 | return 0*x;
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46 | uxi = i;
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47 | }
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48 | uxi <<= 1;
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49 | }
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50 | i = uxi - uy.i;
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51 | if (i >> 63 == 0) {
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52 | if (i == 0)
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53 | return 0*x;
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54 | uxi = i;
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55 | }
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56 | for (; uxi>>52 == 0; uxi <<= 1, ex--);
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57 |
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58 | /* scale result */
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59 | if (ex > 0) {
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60 | uxi -= 1ULL << 52;
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61 | uxi |= (uint64_t)ex << 52;
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62 | } else {
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63 | uxi >>= -ex + 1;
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64 | }
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65 | uxi |= (uint64_t)sx << 63;
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66 | ux.i = uxi;
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67 | return ux.f;
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68 | }
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