Motown: Rename Ratio and LinearFunction classes

mojo/services/media/common/cpp/linear_function.h

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef MOJO_SERVICES_MEDIA_COMMON_CPP_LINEAR_FUNCTION_H_
-#define MOJO_SERVICES_MEDIA_COMMON_CPP_LINEAR_FUNCTION_H_
-
-#include "mojo/public/cpp/environment/logging.h"
-#include "mojo/services/media/common/cpp/ratio.h"
-
-namespace mojo {
-namespace media {
-
-// TODO(dalesat): Consider always allowing inexact results.
-
-// A linear function from int64_t to int64_t with non-negative slope. The
-// representation is in point-slope form. The point is represented as two
-// int64_t values (domain_basis, range_basis), and the slope is represented as
-// the ratio of two uint32_t values (range_delta / domain_delta). 'Domain'
-// refers to the input space, and 'range' refers to the output space.
-struct LinearFunction {
-  // Applies a linear function.
-  static int64_t Apply(int64_t domain_basis,
-                       int64_t range_basis,
-                       const Ratio& slope,  // range_delta / domain_delta
-                       int64_t domain_input);
-
-  // Applies the inverse of a linear function.
-  static int64_t ApplyInverse(int64_t domain_basis,
-                              int64_t range_basis,
-                              const Ratio& slope,  // range_delta / domain_delta
-                              int64_t range_input) {
-    MOJO_DCHECK(slope.denominator() != 0u);
-    return Apply(range_basis, domain_basis, slope.Inverse(), range_input);
-  }
-
-  // Composes two linear functions B->C and A->B producing A->C. If exact is
-  // true, DCHECKs on loss of precision.
-  static LinearFunction Compose(const LinearFunction& bc,
-                                const LinearFunction& ab,
-                                bool exact = true);
-
-  LinearFunction() : domain_basis_(0), range_basis_(0) {}
-
-  LinearFunction(int64_t domain_basis,
-                 int64_t range_basis,
-                 uint32_t domain_delta,
-                 uint32_t range_delta)
-      : domain_basis_(domain_basis),
-        range_basis_(range_basis),
-        slope_(range_delta, domain_delta) {}
-
-  LinearFunction(int64_t domain_basis,
-                 int64_t range_basis,
-                 const Ratio& slope)  // range_delta / domain_delta
-      : domain_basis_(domain_basis),
-        range_basis_(range_basis),
-        slope_(slope) {}
-
-  explicit LinearFunction(const Ratio& slope)  // range_delta / domain_delta
-      : domain_basis_(0),
-        range_basis_(0),
-        slope_(slope) {}
-
-  // Applies the function. Returns Ratio::kOverflow on overflow.
-  int64_t Apply(int64_t domain_input) const {
-    return Apply(domain_basis_, range_basis_, slope_, domain_input);
-  }
-
-  // Applies the inverse of the function. Returns Ratio::kOverflow on overflow.
-  int64_t ApplyInverse(int64_t range_input) const {
-    MOJO_DCHECK(slope_.denominator() != 0u);
-    return ApplyInverse(domain_basis_, range_basis_, slope_, range_input);
-  }
-
-  // Applies the function.  Returns Ratio::kOverflow on overflow.
-  int64_t operator()(int64_t domain_input) const { return Apply(domain_input); }
-
-  // Returns a linear function that is the inverse if this linear function.
-  LinearFunction Inverse() const {
-    MOJO_DCHECK(slope_.denominator() != 0u);
-    return LinearFunction(range_basis_, domain_basis_, slope_.Inverse());
-  }
-
-  int64_t domain_basis() const { return domain_basis_; }
-
-  int64_t range_basis() const { return range_basis_; }
-
-  const Ratio& slope() const { return slope_; }
-
-  uint32_t domain_delta() const { return slope_.denominator(); }
-
-  uint32_t range_delta() const { return slope_.numerator(); }
-
-  int64_t domain_basis_;
-  int64_t range_basis_;
-  Ratio slope_;  // range_delta / domain_delta
-};
-
-// Tests two linear functions for equality. Equality requires equal basis
-// values.
-inline bool operator==(const LinearFunction& a, const LinearFunction& b) {
-  return a.domain_basis() == b.domain_basis() &&
-         a.range_basis() == b.range_basis() && a.slope() == b.slope();
-}
-
-// Tests two linear functions for inequality. Equality requires equal basis
-// values.
-inline bool operator!=(const LinearFunction& a, const LinearFunction& b) {
-  return !(a == b);
-}
-
-// Composes two linear functions B->C and A->B producing A->C. DCHECKs on
-// loss of precision.
-inline LinearFunction operator*(const LinearFunction& bc,
-                                const LinearFunction& ab) {
-  return LinearFunction::Compose(bc, ab);
-}
-
-}  // namespace media
-}  // namespace mojo
-
-#endif  // MOJO_SERVICES_MEDIA_COMMON_CPP_LINEAR_FUNCTION_H_