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 } 48
