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      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 "dictionary/structure/pt_common/dynamic_pt_writing_utils.h"
     18 
     19 #include <cstddef>
     20 #include <cstdint>
     21 #include <cstdlib>
     22 
     23 #include "dictionary/utils/buffer_with_extendable_buffer.h"
     24 
     25 namespace latinime {
     26 
     27 const size_t DynamicPtWritingUtils::MAX_PTNODE_ARRAY_SIZE_TO_USE_SMALL_SIZE_FIELD = 0x7F;
     28 const size_t DynamicPtWritingUtils::MAX_PTNODE_ARRAY_SIZE = 0x7FFF;
     29 const int DynamicPtWritingUtils::SMALL_PTNODE_ARRAY_SIZE_FIELD_SIZE = 1;
     30 const int DynamicPtWritingUtils::LARGE_PTNODE_ARRAY_SIZE_FIELD_SIZE = 2;
     31 const int DynamicPtWritingUtils::LARGE_PTNODE_ARRAY_SIZE_FIELD_SIZE_FLAG = 0x8000;
     32 const int DynamicPtWritingUtils::DICT_OFFSET_FIELD_SIZE = 3;
     33 const int DynamicPtWritingUtils::MAX_DICT_OFFSET_VALUE = 0x7FFFFF;
     34 const int DynamicPtWritingUtils::MIN_DICT_OFFSET_VALUE = -0x7FFFFF;
     35 const int DynamicPtWritingUtils::DICT_OFFSET_NEGATIVE_FLAG = 0x800000;
     36 const int DynamicPtWritingUtils::NODE_FLAG_FIELD_SIZE = 1;
     37 
     38 /* static */ bool DynamicPtWritingUtils::writeEmptyDictionary(
     39         BufferWithExtendableBuffer *const buffer, const int rootPos) {
     40     int writingPos = rootPos;
     41     if (!writePtNodeArraySizeAndAdvancePosition(buffer, 0 /* arraySize */, &writingPos)) {
     42         return false;
     43     }
     44     return writeForwardLinkPositionAndAdvancePosition(buffer, NOT_A_DICT_POS /* forwardLinkPos */,
     45             &writingPos);
     46 }
     47 
     48 /* static */ bool DynamicPtWritingUtils::writeForwardLinkPositionAndAdvancePosition(
     49         BufferWithExtendableBuffer *const buffer, const int forwardLinkPos,
     50         int *const forwardLinkFieldPos) {
     51     return writeDictOffset(buffer, forwardLinkPos, (*forwardLinkFieldPos), forwardLinkFieldPos);
     52 }
     53 
     54 /* static */ bool DynamicPtWritingUtils::writePtNodeArraySizeAndAdvancePosition(
     55         BufferWithExtendableBuffer *const buffer, const size_t arraySize,
     56         int *const arraySizeFieldPos) {
     57     // Currently, all array size field to be created has LARGE_PTNODE_ARRAY_SIZE_FIELD_SIZE to
     58     // simplify updating process.
     59     // TODO: Use SMALL_PTNODE_ARRAY_SIZE_FIELD_SIZE for small arrays.
     60     /*if (arraySize <= MAX_PTNODE_ARRAY_SIZE_TO_USE_SMALL_SIZE_FIELD) {
     61         return buffer->writeUintAndAdvancePosition(arraySize, SMALL_PTNODE_ARRAY_SIZE_FIELD_SIZE,
     62                 arraySizeFieldPos);
     63     } else */
     64     if (arraySize <= MAX_PTNODE_ARRAY_SIZE) {
     65         uint32_t data = arraySize | LARGE_PTNODE_ARRAY_SIZE_FIELD_SIZE_FLAG;
     66         return buffer->writeUintAndAdvancePosition(data, LARGE_PTNODE_ARRAY_SIZE_FIELD_SIZE,
     67                 arraySizeFieldPos);
     68     } else {
     69         AKLOGI("PtNode array size cannot be written because arraySize is too large: %zd",
     70                 arraySize);
     71         ASSERT(false);
     72         return false;
     73     }
     74 }
     75 
     76 /* static */ bool DynamicPtWritingUtils::writeFlagsAndAdvancePosition(
     77         BufferWithExtendableBuffer *const buffer,
     78         const DynamicPtReadingUtils::NodeFlags nodeFlags, int *const nodeFlagsFieldPos) {
     79     return buffer->writeUintAndAdvancePosition(nodeFlags, NODE_FLAG_FIELD_SIZE, nodeFlagsFieldPos);
     80 }
     81 
     82 // Note that parentOffset is offset from node's head position.
     83 /* static */ bool DynamicPtWritingUtils::writeParentPosOffsetAndAdvancePosition(
     84         BufferWithExtendableBuffer *const buffer, const int parentPos, const int basePos,
     85         int *const parentPosFieldPos) {
     86     return writeDictOffset(buffer, parentPos, basePos, parentPosFieldPos);
     87 }
     88 
     89 /* static */ bool DynamicPtWritingUtils::writeCodePointsAndAdvancePosition(
     90         BufferWithExtendableBuffer *const buffer, const int *const codePoints,
     91         const int codePointCount, int *const codePointFieldPos) {
     92     if (codePointCount <= 0) {
     93         AKLOGI("code points cannot be written because codePointCount is invalid: %d",
     94                 codePointCount);
     95         ASSERT(false);
     96         return false;
     97     }
     98     const bool hasMultipleCodePoints = codePointCount > 1;
     99     return buffer->writeCodePointsAndAdvancePosition(codePoints, codePointCount,
    100             hasMultipleCodePoints, codePointFieldPos);
    101 }
    102 
    103 /* static */ bool DynamicPtWritingUtils::writeChildrenPositionAndAdvancePosition(
    104         BufferWithExtendableBuffer *const buffer, const int childrenPosition,
    105         int *const childrenPositionFieldPos) {
    106     return writeDictOffset(buffer, childrenPosition, (*childrenPositionFieldPos),
    107             childrenPositionFieldPos);
    108 }
    109 
    110 /* static */ bool DynamicPtWritingUtils::writeDictOffset(BufferWithExtendableBuffer *const buffer,
    111         const int targetPos, const int basePos, int *const offsetFieldPos) {
    112     int offset = targetPos - basePos;
    113     if (targetPos == NOT_A_DICT_POS) {
    114         offset = DynamicPtReadingUtils::DICT_OFFSET_INVALID;
    115     } else if (offset == 0) {
    116         offset = DynamicPtReadingUtils::DICT_OFFSET_ZERO_OFFSET;
    117     }
    118     if (offset > MAX_DICT_OFFSET_VALUE || offset < MIN_DICT_OFFSET_VALUE) {
    119         AKLOGI("offset cannot be written because the offset is too large or too small: %d",
    120                 offset);
    121         ASSERT(false);
    122         return false;
    123     }
    124     uint32_t data = 0;
    125     if (offset >= 0) {
    126         data = offset;
    127     } else {
    128         data = abs(offset) | DICT_OFFSET_NEGATIVE_FLAG;
    129     }
    130     return buffer->writeUintAndAdvancePosition(data, DICT_OFFSET_FIELD_SIZE, offsetFieldPos);
    131 }
    132 }
    133