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
FixedBlockReader(FixedBlockProcessor & fixedBlockProcessor)25 FixedBlockReader::FixedBlockReader(FixedBlockProcessor &fixedBlockProcessor)
26 : FixedBlockAdapter(fixedBlockProcessor) {
27 mPosition = mSize;
28 }
29
open(int32_t bytesPerFixedBlock)30 int32_t FixedBlockReader::open(int32_t bytesPerFixedBlock) {
31 int32_t result = FixedBlockAdapter::open(bytesPerFixedBlock);
32 mPosition = 0;
33 mValid = 0;
34 return result;
35 }
36
readFromStorage(uint8_t * buffer,int32_t numBytes)37 int32_t FixedBlockReader::readFromStorage(uint8_t *buffer, int32_t numBytes) {
38 int32_t bytesToRead = numBytes;
39 int32_t dataAvailable = mValid - mPosition;
40 if (bytesToRead > dataAvailable) {
41 bytesToRead = dataAvailable;
42 }
43 memcpy(buffer, mStorage.get() + mPosition, bytesToRead);
44 mPosition += bytesToRead;
45 return bytesToRead;
46 }
47
read(uint8_t * buffer,int32_t numBytes)48 int32_t FixedBlockReader::read(uint8_t *buffer, int32_t numBytes) {
49 int32_t bytesRead;
50 int32_t bytesLeft = numBytes;
51 while(bytesLeft > 0) {
52 if (mPosition < mValid) {
53 // Use up bytes currently in storage.
54 bytesRead = readFromStorage(buffer, bytesLeft);
55 buffer += bytesRead;
56 bytesLeft -= bytesRead;
57 } else if (bytesLeft >= mSize) {
58 // Nothing in storage. Read through if enough for a complete block.
59 bytesRead = mFixedBlockProcessor.onProcessFixedBlock(buffer, mSize);
60 if (bytesRead < 0) return bytesRead;
61 buffer += bytesRead;
62 bytesLeft -= bytesRead;
63 } else {
64 // Just need a partial block so we have to reload storage.
65 bytesRead = mFixedBlockProcessor.onProcessFixedBlock(mStorage.get(), mSize);
66 if (bytesRead < 0) return bytesRead;
67 mPosition = 0;
68 mValid = bytesRead;
69 if (bytesRead == 0) break;
70 }
71 }
72 return numBytes - bytesLeft;
73 }
74