source:
asp3_tinet_ecnl_rx/trunk/musl-1.1.18/src/math/ilogbf.c
Last change on this file was 337, checked in by , 6 years ago | |
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File size: 438 bytes |
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1 | #include <limits.h> |
2 | #include "libm.h" |
3 | |
4 | int ilogbf(float x) |
5 | { |
6 | #pragma STDC FENV_ACCESS ON |
7 | union {float f; uint32_t i;} u = {x}; |
8 | uint32_t i = u.i; |
9 | int e = i>>23 & 0xff; |
10 | |
11 | if (!e) { |
12 | i <<= 9; |
13 | if (i == 0) { |
14 | FORCE_EVAL(0/0.0f); |
15 | return FP_ILOGB0; |
16 | } |
17 | /* subnormal x */ |
18 | for (e = -0x7f; i>>31 == 0; e--, i<<=1); |
19 | return e; |
20 | } |
21 | if (e == 0xff) { |
22 | FORCE_EVAL(0/0.0f); |
23 | return i<<9 ? FP_ILOGBNAN : INT_MAX; |
24 | } |
25 | return e - 0x7f; |
26 | } |
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