source:
EcnlProtoTool/trunk/musl-1.1.18/src/math/scalbnf.c@
444
Last change on this file since 444 was 444, checked in by , 4 years ago | |
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File size: 477 bytes |
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1 | #include <math.h> |
2 | #include <stdint.h> |
3 | |
4 | float scalbnf(float x, int n) |
5 | { |
6 | union {float f; uint32_t i;} u; |
7 | float_t y = x; |
8 | |
9 | if (n > 127) { |
10 | y *= 0x1p127f; |
11 | n -= 127; |
12 | if (n > 127) { |
13 | y *= 0x1p127f; |
14 | n -= 127; |
15 | if (n > 127) |
16 | n = 127; |
17 | } |
18 | } else if (n < -126) { |
19 | y *= 0x1p-126f * 0x1p24f; |
20 | n += 126 - 24; |
21 | if (n < -126) { |
22 | y *= 0x1p-126f * 0x1p24f; |
23 | n += 126 - 24; |
24 | if (n < -126) |
25 | n = -126; |
26 | } |
27 | } |
28 | u.i = (uint32_t)(0x7f+n)<<23; |
29 | x = y * u.f; |
30 | return x; |
31 | } |
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