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:
576 bytes
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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 scalbn(double x, int n)
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5 | {
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6 | union {double f; uint64_t i;} u;
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7 | double_t y = x;
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8 |
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9 | if (n > 1023) {
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10 | y *= 0x1p1023;
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11 | n -= 1023;
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12 | if (n > 1023) {
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13 | y *= 0x1p1023;
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14 | n -= 1023;
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15 | if (n > 1023)
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16 | n = 1023;
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17 | }
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18 | } else if (n < -1022) {
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19 | /* make sure final n < -53 to avoid double
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20 | rounding in the subnormal range */
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21 | y *= 0x1p-1022 * 0x1p53;
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22 | n += 1022 - 53;
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23 | if (n < -1022) {
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24 | y *= 0x1p-1022 * 0x1p53;
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25 | n += 1022 - 53;
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26 | if (n < -1022)
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27 | n = -1022;
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28 | }
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29 | }
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30 | u.i = (uint64_t)(0x3ff+n)<<52;
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31 | x = y * u.f;
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32 | return x;
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33 | }
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