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author | Jason Simmons <jsimmons@google.com> | 2011-06-29 13:48:39 -0700 |
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committer | Android (Google) Code Review <android-gerrit@google.com> | 2011-06-29 13:48:39 -0700 |
commit | 9e1fb41b4fbfbd190560cf48f24939703a13eca5 (patch) | |
tree | 8621dd8dd0a0e32e8883dbdaa02b1610018b05c4 /include | |
parent | 5c226b835812630d9dc67ca02ca03dddaee5b6c7 (diff) | |
parent | aa11965bd55b8344104ebb0c9ebf39ee0cced03f (diff) | |
download | frameworks_base-9e1fb41b4fbfbd190560cf48f24939703a13eca5.zip frameworks_base-9e1fb41b4fbfbd190560cf48f24939703a13eca5.tar.gz frameworks_base-9e1fb41b4fbfbd190560cf48f24939703a13eca5.tar.bz2 |
Merge "Add a linear transform library to libutils"
Diffstat (limited to 'include')
-rw-r--r-- | include/utils/LinearTransform.h | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/include/utils/LinearTransform.h b/include/utils/LinearTransform.h new file mode 100644 index 0000000..04cb355 --- /dev/null +++ b/include/utils/LinearTransform.h @@ -0,0 +1,64 @@ +/* + * Copyright (C) 2011 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#ifndef _LIBS_UTILS_LINEAR_TRANSFORM_H +#define _LIBS_UTILS_LINEAR_TRANSFORM_H + +#include <stdint.h> + +namespace android { + +// LinearTransform defines a structure which hold the definition of a +// transformation from single dimensional coordinate system A into coordinate +// system B (and back again). Values in A and in B are 64 bit, the linear +// scale factor is expressed as a rational number using two 32 bit values. +// +// Specifically, let +// f(a) = b +// F(b) = f^-1(b) = a +// then +// +// f(a) = (((a - a_zero) * a_to_b_numer) / a_to_b_denom) + b_zero; +// +// and +// +// F(b) = (((b - b_zero) * a_to_b_denom) / a_to_b_numer) + a_zero; +// +struct LinearTransform { + int64_t a_zero; + int64_t b_zero; + int32_t a_to_b_numer; + uint32_t a_to_b_denom; + + // Transform from A->B + // Returns true on success, or false in the case of a singularity or an + // overflow. + bool doForwardTransform(int64_t a_in, int64_t* b_out) const; + + // Transform from B->A + // Returns true on success, or false in the case of a singularity or an + // overflow. + bool doReverseTransform(int64_t b_in, int64_t* a_out) const; + + // Helpers which will reduce the fraction N/D using Euclid's method. + template <class T> static void reduce(T* N, T* D); + static void reduce(int32_t* N, uint32_t* D); +}; + + +} + +#endif // _LIBS_UTILS_LINEAR_TRANSFORM_H |