1//===- StreamableMemoryObject.cpp - Streamable data interface -------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "llvm/Support/StreamableMemoryObject.h"
11#include "llvm/Support/Compiler.h"
12#include <cassert>
13#include <cstring>
14
15
16using namespace llvm;
17
18namespace {
19
20class RawMemoryObject : public StreamableMemoryObject {
21public:
22  RawMemoryObject(const unsigned char *Start, const unsigned char *End) :
23    FirstChar(Start), LastChar(End) {
24    assert(LastChar >= FirstChar && "Invalid start/end range");
25  }
26
27  virtual uint64_t getBase() const LLVM_OVERRIDE { return 0; }
28  virtual uint64_t getExtent() const LLVM_OVERRIDE {
29    return LastChar - FirstChar;
30  }
31  virtual int readByte(uint64_t address, uint8_t* ptr) const LLVM_OVERRIDE;
32  virtual int readBytes(uint64_t address,
33                        uint64_t size,
34                        uint8_t* buf,
35                        uint64_t* copied) const LLVM_OVERRIDE;
36  virtual const uint8_t *getPointer(uint64_t address,
37                                    uint64_t size) const LLVM_OVERRIDE;
38  virtual bool isValidAddress(uint64_t address) const LLVM_OVERRIDE {
39    return validAddress(address);
40  }
41  virtual bool isObjectEnd(uint64_t address) const LLVM_OVERRIDE {
42    return objectEnd(address);
43  }
44
45private:
46  const uint8_t* const FirstChar;
47  const uint8_t* const LastChar;
48
49  // These are implemented as inline functions here to avoid multiple virtual
50  // calls per public function
51  bool validAddress(uint64_t address) const {
52    return static_cast<ptrdiff_t>(address) < LastChar - FirstChar;
53  }
54  bool objectEnd(uint64_t address) const {
55    return static_cast<ptrdiff_t>(address) == LastChar - FirstChar;
56  }
57
58  RawMemoryObject(const RawMemoryObject&) LLVM_DELETED_FUNCTION;
59  void operator=(const RawMemoryObject&) LLVM_DELETED_FUNCTION;
60};
61
62int RawMemoryObject::readByte(uint64_t address, uint8_t* ptr) const {
63  if (!validAddress(address)) return -1;
64  *ptr = *((uint8_t *)(uintptr_t)(address + FirstChar));
65  return 0;
66}
67
68int RawMemoryObject::readBytes(uint64_t address,
69                               uint64_t size,
70                               uint8_t* buf,
71                               uint64_t* copied) const {
72  if (!validAddress(address) || !validAddress(address + size - 1)) return -1;
73  memcpy(buf, (uint8_t *)(uintptr_t)(address + FirstChar), size);
74  if (copied) *copied = size;
75  return size;
76}
77
78const uint8_t *RawMemoryObject::getPointer(uint64_t address,
79                                           uint64_t size) const {
80  return FirstChar + address;
81}
82} // anonymous namespace
83
84namespace llvm {
85// If the bitcode has a header, then its size is known, and we don't have to
86// block until we actually want to read it.
87bool StreamingMemoryObject::isValidAddress(uint64_t address) const {
88  if (ObjectSize && address < ObjectSize) return true;
89    return fetchToPos(address);
90}
91
92bool StreamingMemoryObject::isObjectEnd(uint64_t address) const {
93  if (ObjectSize) return address == ObjectSize;
94  fetchToPos(address);
95  return address == ObjectSize && address != 0;
96}
97
98uint64_t StreamingMemoryObject::getExtent() const {
99  if (ObjectSize) return ObjectSize;
100  size_t pos = BytesRead + kChunkSize;
101  // keep fetching until we run out of bytes
102  while (fetchToPos(pos)) pos += kChunkSize;
103  return ObjectSize;
104}
105
106int StreamingMemoryObject::readByte(uint64_t address, uint8_t* ptr) const {
107  if (!fetchToPos(address)) return -1;
108  *ptr = Bytes[address + BytesSkipped];
109  return 0;
110}
111
112int StreamingMemoryObject::readBytes(uint64_t address,
113                                     uint64_t size,
114                                     uint8_t* buf,
115                                     uint64_t* copied) const {
116  if (!fetchToPos(address + size - 1)) return -1;
117  memcpy(buf, &Bytes[address + BytesSkipped], size);
118  if (copied) *copied = size;
119  return 0;
120}
121
122bool StreamingMemoryObject::dropLeadingBytes(size_t s) {
123  if (BytesRead < s) return true;
124  BytesSkipped = s;
125  BytesRead -= s;
126  return false;
127}
128
129void StreamingMemoryObject::setKnownObjectSize(size_t size) {
130  ObjectSize = size;
131  Bytes.reserve(size);
132}
133
134StreamableMemoryObject *getNonStreamedMemoryObject(
135    const unsigned char *Start, const unsigned char *End) {
136  return new RawMemoryObject(Start, End);
137}
138
139StreamableMemoryObject::~StreamableMemoryObject() { }
140
141StreamingMemoryObject::StreamingMemoryObject(DataStreamer *streamer) :
142  Bytes(kChunkSize), Streamer(streamer), BytesRead(0), BytesSkipped(0),
143  ObjectSize(0), EOFReached(false) {
144  BytesRead = streamer->GetBytes(&Bytes[0], kChunkSize);
145}
146}
147