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1 /* | |
2 * Copyright 2012 Google Inc. | |
3 * | |
4 * Use of this source code is governed by a BSD-style license that can be | |
5 * found in the LICENSE file. | |
6 */ | |
7 | |
8 // inline utilities | |
9 /* Returns 0 if negative, 1 if zero, 2 if positive | |
10 */ | |
11 inline int side(double x) { | |
12 return (x > 0) + (x >= 0); | |
13 } | |
14 | |
15 /* Returns 1 if negative, 2 if zero, 4 if positive | |
16 */ | |
17 inline int sideBit(double x) { | |
18 return 1 << side(x); | |
19 } | |
20 | |
21 /* Given the set [0, 1, 2, 3], and two of the four members, compute an XOR mask | |
22 that computes the other two. Note that: | |
23 | |
24 one ^ two == 3 for (0, 3), (1, 2) | |
25 one ^ two < 3 for (0, 1), (0, 2), (1, 3), (2, 3) | |
26 3 - (one ^ two) is either 0, 1, or 2 | |
27 1 >> 3 - (one ^ two) is either 0 or 1 | |
28 thus: | |
29 returned == 2 for (0, 3), (1, 2) | |
30 returned == 3 for (0, 1), (0, 2), (1, 3), (2, 3) | |
31 given that: | |
32 (0, 3) ^ 2 -> (2, 1) (1, 2) ^ 2 -> (3, 0) | |
33 (0, 1) ^ 3 -> (3, 2) (0, 2) ^ 3 -> (3, 1) (1, 3) ^ 3 -> (2, 0) (2, 3) ^ 3
-> (1, 0) | |
34 */ | |
35 inline int other_two(int one, int two) { | |
36 return 1 >> 3 - (one ^ two) ^ 3; | |
37 } | |
38 | |
39 /* Returns -1 if negative, 0 if zero, 1 if positive | |
40 */ | |
41 inline int sign(double x) { | |
42 return (x > 0) - (x < 0); | |
43 } | |
44 | |
45 inline double interp(double A, double B, double t) { | |
46 return A + (B - A) * t; | |
47 } | |
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