xref: /third_party/lzma/CPP/7zip/Common/InBuffer.cpp (revision 370b324c) 
1// InBuffer.cpp
2
3#include "StdAfx.h"
4
5#include "../../../C/Alloc.h"
6
7#include "InBuffer.h"
8
9CInBufferBase::CInBufferBase() throw():
10  _buf(NULL),
11  _bufLim(NULL),
12  _bufBase(NULL),
13  _stream(NULL),
14  _processedSize(0),
15  _bufSize(0),
16  _wasFinished(false),
17  NumExtraBytes(0)
18{}
19
20bool CInBuffer::Create(size_t bufSize) throw()
21{
22  const unsigned kMinBlockSize = 1;
23  if (bufSize < kMinBlockSize)
24    bufSize = kMinBlockSize;
25  if (_bufBase != NULL && _bufSize == bufSize)
26    return true;
27  Free();
28  _bufSize = bufSize;
29  _bufBase = (Byte *)::MidAlloc(bufSize);
30  return (_bufBase != NULL);
31}
32
33void CInBuffer::Free() throw()
34{
35  ::MidFree(_bufBase);
36  _bufBase = NULL;
37}
38
39void CInBufferBase::Init() throw()
40{
41  _processedSize = 0;
42  _buf = _bufBase;
43  _bufLim = _buf;
44  _wasFinished = false;
45  #ifdef Z7_NO_EXCEPTIONS
46  ErrorCode = S_OK;
47  #endif
48  NumExtraBytes = 0;
49}
50
51bool CInBufferBase::ReadBlock()
52{
53  #ifdef Z7_NO_EXCEPTIONS
54  if (ErrorCode != S_OK)
55    return false;
56  #endif
57  if (_wasFinished)
58    return false;
59  _processedSize += (size_t)(_buf - _bufBase);
60  _buf = _bufBase;
61  _bufLim = _bufBase;
62  UInt32 processed;
63  // FIX_ME: we can improve it to support (_bufSize >= (1 << 32))
64  const HRESULT result = _stream->Read(_bufBase, (UInt32)_bufSize, &processed);
65  #ifdef Z7_NO_EXCEPTIONS
66  ErrorCode = result;
67  #else
68  if (result != S_OK)
69    throw CInBufferException(result);
70  #endif
71  _bufLim = _buf + processed;
72  _wasFinished = (processed == 0);
73  return !_wasFinished;
74}
75
76bool CInBufferBase::ReadByte_FromNewBlock(Byte &b)
77{
78  if (!ReadBlock())
79  {
80    // 22.00: we don't increment (NumExtraBytes) here
81    // NumExtraBytes++;
82    b = 0xFF;
83    return false;
84  }
85  b = *_buf++;
86  return true;
87}
88
89Byte CInBufferBase::ReadByte_FromNewBlock()
90{
91  if (!ReadBlock())
92  {
93    NumExtraBytes++;
94    return 0xFF;
95  }
96  return *_buf++;
97}
98
99size_t CInBufferBase::ReadBytes(Byte *buf, size_t size)
100{
101  size_t num = 0;
102  for (;;)
103  {
104    const size_t rem = (size_t)(_bufLim - _buf);
105    if (size <= rem)
106    {
107      if (size != 0)
108      {
109        memcpy(buf, _buf, size);
110        _buf += size;
111        num += size;
112      }
113      return num;
114    }
115    if (rem != 0)
116    {
117      memcpy(buf, _buf, rem);
118      _buf += rem;
119      buf += rem;
120      num += rem;
121      size -= rem;
122    }
123    if (!ReadBlock())
124      return num;
125  }
126
127  /*
128  if ((size_t)(_bufLim - _buf) >= size)
129  {
130    const Byte *src = _buf;
131    for (size_t i = 0; i < size; i++)
132      buf[i] = src[i];
133    _buf += size;
134    return size;
135  }
136  for (size_t i = 0; i < size; i++)
137  {
138    if (_buf >= _bufLim)
139      if (!ReadBlock())
140        return i;
141    buf[i] = *_buf++;
142  }
143  return size;
144  */
145}
146
147size_t CInBufferBase::Skip(size_t size)
148{
149  size_t processed = 0;
150  for (;;)
151  {
152    const size_t rem = (size_t)(_bufLim - _buf);
153    if (rem >= size)
154    {
155      _buf += size;
156      return processed + size;
157    }
158    _buf += rem;
159    processed += rem;
160    size -= rem;
161    if (!ReadBlock())
162      return processed;
163  }
164}
165