1 /* 2 * Copyright (C) 2017 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 <stdint.h> 18 #include <memory.h> 19 20 #include "FixedBlockAdapter.h" 21 22 #include "FixedBlockReader.h" 23 24 25 FixedBlockReader::FixedBlockReader(FixedBlockProcessor &fixedBlockProcessor) 26 : FixedBlockAdapter(fixedBlockProcessor) { 27 mPosition = mSize; 28 } 29 30 int32_t FixedBlockReader::open(int32_t bytesPerFixedBlock) { 31 int32_t result = FixedBlockAdapter::open(bytesPerFixedBlock); 32 mPosition = mSize; // Indicate no data in storage. 33 return result; 34 } 35 36 int32_t FixedBlockReader::readFromStorage(uint8_t *buffer, int32_t numBytes) { 37 int32_t bytesToRead = numBytes; 38 int32_t dataAvailable = mSize - mPosition; 39 if (bytesToRead > dataAvailable) { 40 bytesToRead = dataAvailable; 41 } 42 memcpy(buffer, mStorage + mPosition, bytesToRead); 43 mPosition += bytesToRead; 44 return bytesToRead; 45 } 46 47 int32_t FixedBlockReader::processVariableBlock(uint8_t *buffer, int32_t numBytes) { 48 int32_t result = 0; 49 int32_t bytesLeft = numBytes; 50 while(bytesLeft > 0 && result == 0) { 51 if (mPosition < mSize) { 52 // Use up bytes currently in storage. 53 int32_t bytesRead = readFromStorage(buffer, bytesLeft); 54 buffer += bytesRead; 55 bytesLeft -= bytesRead; 56 } else if (bytesLeft >= mSize) { 57 // Read through if enough for a complete block. 58 result = mFixedBlockProcessor.onProcessFixedBlock(buffer, mSize); 59 buffer += mSize; 60 bytesLeft -= mSize; 61 } else { 62 // Just need a partial block so we have to use storage. 63 result = mFixedBlockProcessor.onProcessFixedBlock(mStorage, mSize); 64 mPosition = 0; 65 } 66 } 67 return result; 68 } 69 70
