sparse_table.cpp revision ef665816d07daa9aea74b4f8c34939b6801bbbcd 
1/*
2 * Copyright (C) 2013, 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
17#include "suggest/policyimpl/dictionary/utils/sparse_table.h"
18
19namespace latinime {
20
21const int SparseTable::NOT_EXIST = -1;
22const int SparseTable::INDEX_SIZE = 4;
23
24bool SparseTable::contains(const int id) const {
25    const int readingPos = getPosInIndexTable(id);
26    if (id < 0 || mIndexTableBuffer->getTailPosition() <= readingPos) {
27        return false;
28    }
29    const int index = mIndexTableBuffer->readUint(INDEX_SIZE, readingPos);
30    return index != NOT_EXIST;
31}
32
33uint32_t SparseTable::get(const int id) const {
34    const int indexTableReadingPos = getPosInIndexTable(id);
35    const int index = mIndexTableBuffer->readUint(INDEX_SIZE, indexTableReadingPos);
36    const int contentTableReadingPos = getPosInContentTable(id, index);
37    if (contentTableReadingPos < 0
38            || contentTableReadingPos >= mContentTableBuffer->getTailPosition()) {
39        AKLOGE("contentTableReadingPos(%d) is invalid. id: %d, index: %d",
40                contentTableReadingPos, id, index);
41        return NOT_A_DICT_POS;
42    }
43    const int contentValue = mContentTableBuffer->readUint(mDataSize, contentTableReadingPos);
44    return contentValue == NOT_EXIST ? NOT_A_DICT_POS : contentValue;
45}
46
47bool SparseTable::set(const int id, const uint32_t value) {
48    const int posInIndexTable = getPosInIndexTable(id);
49    // Extends the index table if needed.
50    int tailPos = mIndexTableBuffer->getTailPosition();
51    while (tailPos <= posInIndexTable) {
52        if (!mIndexTableBuffer->writeUintAndAdvancePosition(NOT_EXIST, INDEX_SIZE, &tailPos)) {
53            AKLOGE("cannot extend index table. tailPos: %d to: %d", tailPos, posInIndexTable);
54            return false;
55        }
56    }
57    if (contains(id)) {
58        // The entry is already in the content table.
59        const int index = mIndexTableBuffer->readUint(INDEX_SIZE, posInIndexTable);
60        if (!mContentTableBuffer->writeUint(value, mDataSize, getPosInContentTable(id, index))) {
61            AKLOGE("cannot update value %d. pos: %d, tailPos: %d, mDataSize: %d", value,
62                    getPosInContentTable(id, index), mContentTableBuffer->getTailPosition(),
63                    mDataSize);
64            return false;
65        }
66        return true;
67    }
68    // The entry is not in the content table.
69    // Create new entry in the content table.
70    const int index = getIndexFromContentTablePos(mContentTableBuffer->getTailPosition());
71    if (!mIndexTableBuffer->writeUint(index, INDEX_SIZE, posInIndexTable)) {
72        AKLOGE("cannot write index %d. pos %d", index, posInIndexTable);
73        return false;
74    }
75    // Write a new block that containing the entry to be set.
76    int writingPos = getPosInContentTable(0 /* id */, index);
77    for (int i = 0; i < mBlockSize; ++i) {
78        if (!mContentTableBuffer->writeUintAndAdvancePosition(NOT_EXIST, mDataSize,
79                &writingPos)) {
80            AKLOGE("cannot write content table to extend. writingPos: %d, tailPos: %d, "
81                    "mDataSize: %d", writingPos, mContentTableBuffer->getTailPosition(), mDataSize);
82            return false;
83        }
84    }
85    return mContentTableBuffer->writeUint(value, mDataSize, getPosInContentTable(id, index));
86}
87
88int SparseTable::getIndexFromContentTablePos(const int contentTablePos) const {
89    return contentTablePos / mDataSize / mBlockSize;
90}
91
92int SparseTable::getPosInIndexTable(const int id) const {
93    return (id / mBlockSize) * INDEX_SIZE;
94}
95
96int SparseTable::getPosInContentTable(const int id, const int index) const {
97    const int offset = id % mBlockSize;
98    return (index * mBlockSize + offset) * mDataSize;
99}
100
101} // namespace latinime
102