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1/*
2 * Copyright (C) 2023 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
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
17import {AbsoluteEntryIndex, AbsoluteFrameIndex, EntriesRange, FramesRange} from './index_types';
18
19export class FrameMap {
20  readonly lengthEntries: number;
21  readonly lengthFrames: number;
22
23  // These lookup tables allow to convert a "[start_entry; end_entry[" range
24  // to "[start_frame; end_frame[" in O(1) time.
25  //
26  // entryToStartFrame[i] is:
27  // - start_frame of entry_i
28  // - start_frame of the first entry_j (j > i), if entry_i has no associated frames
29  // - undefined, if all the entries with index >= i have no associated frames
30  //
31  // entryToEndFrame[i] is:
32  // - end_frame of entry_i
33  // - end_frame of the last entry_j (j < i), if entry_i has no associated frames
34  // - undefined, if all the entries with index <= i have no associated frames
35  private readonly entryToStartFrame: Array<AbsoluteFrameIndex | undefined>;
36  private readonly entryToEndFrame: Array<AbsoluteFrameIndex | undefined>;
37
38  // These lookup tables allow to convert a "[start_frame; end_frame[" range
39  // to "[start_entry; end_entry[" in O(1) time.
40  //
41  // frameToStartEntry[i] is:
42  // - start_entry of frame_i
43  // - start_entry of the first frame_j (j > i), if frame_i has no associated entries
44  // - undefined, if all the frames with index >= i have no associated entries
45  //
46  // frameToEndEntry[i] is:
47  // - end_entry of frame_i
48  // - end_entry of the last frame_j (j < i), if frame_i has no associated entries
49  // - undefined, if all the frames with index <= i have no associated entries
50  private readonly frameToStartEntry: Array<AbsoluteEntryIndex | undefined>;
51  private readonly frameToEndEntry: Array<AbsoluteEntryIndex | undefined>;
52
53  constructor(
54    lengthEntries: number,
55    lengthFrames: number,
56    entryToStartFrame: Array<AbsoluteFrameIndex | undefined>,
57    entryToEndFrame: Array<AbsoluteFrameIndex | undefined>,
58    frameToStartEntry: Array<AbsoluteEntryIndex | undefined>,
59    frameToEndEntry: Array<AbsoluteEntryIndex | undefined>
60  ) {
61    this.lengthEntries = lengthEntries;
62    this.lengthFrames = lengthFrames;
63    this.entryToStartFrame = entryToStartFrame;
64    this.entryToEndFrame = entryToEndFrame;
65    this.frameToStartEntry = frameToStartEntry;
66    this.frameToEndEntry = frameToEndEntry;
67  }
68
69  getFramesRange(entries: EntriesRange): FramesRange | undefined {
70    entries = this.clampEntriesRangeToFitBounds(entries);
71    if (entries.start >= entries.end) {
72      return undefined;
73    }
74
75    const startFrame = this.getStartFrameOfFirstGreaterOrEqualMappedEntry(entries.start);
76    const endFrame = this.getEndFrameOfLastLowerOrEqualMappedEntry(entries.end - 1);
77
78    if (startFrame === undefined || endFrame === undefined || startFrame >= endFrame) {
79      return undefined;
80    }
81
82    return {start: startFrame, end: endFrame};
83  }
84
85  getFullTraceFramesRange(): FramesRange | undefined {
86    return this.getFramesRange({start: 0, end: this.lengthEntries});
87  }
88
89  getEntriesRange(frames: FramesRange): EntriesRange | undefined {
90    frames = this.clampFramesRangeToFitBounds(frames);
91    if (frames.start >= frames.end) {
92      return undefined;
93    }
94
95    const startEntry = this.getStartEntryOfFirstGreaterOrEqualMappedFrame(frames.start);
96    const endEntry = this.getEndEntryOfLastLowerOrEqualMappedFrame(frames.end - 1);
97
98    if (startEntry === undefined || endEntry === undefined || startEntry >= endEntry) {
99      return undefined;
100    }
101
102    return {start: startEntry, end: endEntry};
103  }
104
105  private getStartFrameOfFirstGreaterOrEqualMappedEntry(
106    entry: AbsoluteEntryIndex
107  ): AbsoluteFrameIndex | undefined {
108    if (entry < 0 || entry >= this.lengthEntries) {
109      throw Error(`Entry index out of bounds: ${entry}`);
110    }
111    return this.entryToStartFrame[entry];
112  }
113
114  private getEndFrameOfLastLowerOrEqualMappedEntry(
115    entry: AbsoluteEntryIndex
116  ): AbsoluteFrameIndex | undefined {
117    if (entry < 0 || entry >= this.lengthEntries) {
118      throw Error(`Entry index out of bounds: ${entry}`);
119    }
120    return this.entryToEndFrame[entry];
121  }
122
123  private getStartEntryOfFirstGreaterOrEqualMappedFrame(
124    frame: AbsoluteFrameIndex
125  ): AbsoluteEntryIndex | undefined {
126    if (frame < 0 || frame >= this.lengthFrames) {
127      throw Error(`Frame index out of bounds: ${frame}`);
128    }
129    return this.frameToStartEntry[frame];
130  }
131
132  private getEndEntryOfLastLowerOrEqualMappedFrame(
133    frame: AbsoluteFrameIndex
134  ): AbsoluteEntryIndex | undefined {
135    if (frame < 0 || frame >= this.lengthFrames) {
136      throw Error(`Frame index out of bounds: ${frame}`);
137    }
138    return this.frameToEndEntry[frame];
139  }
140
141  private clampEntriesRangeToFitBounds(entries: EntriesRange): EntriesRange {
142    return {
143      start: Math.max(entries.start, 0),
144      end: Math.min(entries.end, this.lengthEntries),
145    };
146  }
147
148  private clampFramesRangeToFitBounds(frames: FramesRange): FramesRange {
149    return {
150      start: Math.max(frames.start, 0),
151      end: Math.min(frames.end, this.lengthFrames),
152    };
153  }
154}
155