source:
EcnlProtoTool/trunk/musl-1.1.18/src/math/roundf.c
Last change on this file was 444, checked in by , 4 years ago | |
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File size: 589 bytes |
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1 | #include "libm.h" |
2 | |
3 | #if FLT_EVAL_METHOD==0 |
4 | #define EPS FLT_EPSILON |
5 | #elif FLT_EVAL_METHOD==1 |
6 | #define EPS DBL_EPSILON |
7 | #elif FLT_EVAL_METHOD==2 |
8 | #define EPS LDBL_EPSILON |
9 | #endif |
10 | static const float_t toint = 1/EPS; |
11 | |
12 | float roundf(float x) |
13 | { |
14 | union {float f; uint32_t i;} u = {x}; |
15 | int e = u.i >> 23 & 0xff; |
16 | float_t y; |
17 | |
18 | if (e >= 0x7f+23) |
19 | return x; |
20 | if (u.i >> 31) |
21 | x = -x; |
22 | if (e < 0x7f-1) { |
23 | FORCE_EVAL(x + toint); |
24 | return 0*u.f; |
25 | } |
26 | y = x + toint - toint - x; |
27 | if (y > 0.5f) |
28 | y = y + x - 1; |
29 | else if (y <= -0.5f) |
30 | y = y + x + 1; |
31 | else |
32 | y = y + x; |
33 | if (u.i >> 31) |
34 | y = -y; |
35 | return y; |
36 | } |
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