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) const LLVM_OVERRIDE;
35  virtual const uint8_t *getPointer(uint64_t address,
36                                    uint64_t size) const LLVM_OVERRIDE;
37  virtual bool isValidAddress(uint64_t address) const LLVM_OVERRIDE {
38    return validAddress(address);
39  }
40  virtual bool isObjectEnd(uint64_t address) const LLVM_OVERRIDE {
41    return objectEnd(address);
42  }
43
44private:
45  const uint8_t* const FirstChar;
46  const uint8_t* const LastChar;
47
48  // These are implemented as inline functions here to avoid multiple virtual
49  // calls per public function
50  bool validAddress(uint64_t address) const {
51    return static_cast<ptrdiff_t>(address) < LastChar - FirstChar;
52  }
53  bool objectEnd(uint64_t address) const {
54    return static_cast<ptrdiff_t>(address) == LastChar - FirstChar;
55  }
56
57  RawMemoryObject(const RawMemoryObject&) LLVM_DELETED_FUNCTION;
58  void operator=(const RawMemoryObject&) LLVM_DELETED_FUNCTION;
59};
60
61int RawMemoryObject::readByte(uint64_t address, uint8_t* ptr) const {
62  if (!validAddress(address)) return -1;
63  *ptr = *((uint8_t *)(uintptr_t)(address + FirstChar));
64  return 0;
65}
66
67int RawMemoryObject::readBytes(uint64_t address,
68                               uint64_t size,
69                               uint8_t *buf) const {
70  if (!validAddress(address) || !validAddress(address + size - 1)) return -1;
71  memcpy(buf, (uint8_t *)(uintptr_t)(address + FirstChar), size);
72  return size;
73}
74
75const uint8_t *RawMemoryObject::getPointer(uint64_t address,
76                                           uint64_t size) const {
77  return FirstChar + address;
78}
79} // anonymous namespace
80
81namespace llvm {
82// If the bitcode has a header, then its size is known, and we don't have to
83// block until we actually want to read it.
84bool StreamingMemoryObject::isValidAddress(uint64_t address) const {
85  if (ObjectSize && address < ObjectSize) return true;
86    return fetchToPos(address);
87}
88
89bool StreamingMemoryObject::isObjectEnd(uint64_t address) const {
90  if (ObjectSize) return address == ObjectSize;
91  fetchToPos(address);
92  return address == ObjectSize && address != 0;
93}
94
95uint64_t StreamingMemoryObject::getExtent() const {
96  if (ObjectSize) return ObjectSize;
97  size_t pos = BytesRead + kChunkSize;
98  // keep fetching until we run out of bytes
99  while (fetchToPos(pos)) pos += kChunkSize;
100  return ObjectSize;
101}
102
103int StreamingMemoryObject::readByte(uint64_t address, uint8_t* ptr) const {
104  if (!fetchToPos(address)) return -1;
105  *ptr = Bytes[address + BytesSkipped];
106  return 0;
107}
108
109int StreamingMemoryObject::readBytes(uint64_t address,
110                                     uint64_t size,
111                                     uint8_t *buf) const {
112  if (!fetchToPos(address + size - 1)) return -1;
113  memcpy(buf, &Bytes[address + BytesSkipped], size);
114  return 0;
115}
116
117bool StreamingMemoryObject::dropLeadingBytes(size_t s) {
118  if (BytesRead < s) return true;
119  BytesSkipped = s;
120  BytesRead -= s;
121  return false;
122}
123
124void StreamingMemoryObject::setKnownObjectSize(size_t size) {
125  ObjectSize = size;
126  Bytes.reserve(size);
127}
128
129StreamableMemoryObject *getNonStreamedMemoryObject(
130    const unsigned char *Start, const unsigned char *End) {
131  return new RawMemoryObject(Start, End);
132}
133
134StreamableMemoryObject::~StreamableMemoryObject() { }
135
136StreamingMemoryObject::StreamingMemoryObject(DataStreamer *streamer) :
137  Bytes(kChunkSize), Streamer(streamer), BytesRead(0), BytesSkipped(0),
138  ObjectSize(0), EOFReached(false) {
139  BytesRead = streamer->GetBytes(&Bytes[0], kChunkSize);
140}
141}
142