```/* <![CDATA[ */
function get_sym_list(){return [["Macro","xm",[["_LINEAR_TRANSFORM_H",18]]],["Namespace","xn",[["android",22]]],["Struct","xs",[["LinearTransform",40]]]];} /* ]]> */1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
9 *
10 * Unless required by applicable law or agreed to in writing, software
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef _LINEAR_TRANSFORM_H
18#define _LINEAR_TRANSFORM_H
19
20#include <stdint.h>
21
22namespace android {
23
24// LinearTransform defines a structure which hold the definition of a
25// transformation from single dimensional coordinate system A into coordinate
26// system B (and back again).  Values in A and in B are 64 bit, the linear
27// scale factor is expressed as a rational number using two 32 bit values.
28//
29// Specifically, let
30// f(a) = b
31// F(b) = f^-1(b) = a
32// then
33//
34// f(a) = (((a - a_zero) * a_to_b_numer) / a_to_b_denom) + b_zero;
35//
36// and
37//
38// F(b) = (((b - b_zero) * a_to_b_denom) / a_to_b_numer) + a_zero;
39//
40struct LinearTransform {
41  int64_t  a_zero;
42  int64_t  b_zero;
43  int32_t  a_to_b_numer;
44  uint32_t a_to_b_denom;
45
46  // Transform from A->B
47  // Returns true on success, or false in the case of a singularity or an
48  // overflow.
49  bool doForwardTransform(int64_t a_in, int64_t* b_out) const;
50
51  // Transform from B->A
52  // Returns true on success, or false in the case of a singularity or an
53  // overflow.
54  bool doReverseTransform(int64_t b_in, int64_t* a_out) const;
55
56  // Helpers which will reduce the fraction N/D using Euclid's method.
57  template <class T> static void reduce(T* N, T* D);
58  static void reduce(int32_t* N, uint32_t* D);
59};
60
61
62}
63
64#endif  // _LINEAR_TRANSFORM_H
65```