LLVM  3.7.0
MemoryObject.h
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1 //===- MemoryObject.h - Abstract memory interface ---------------*- C++ -*-===//
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 #ifndef LLVM_SUPPORT_MEMORYOBJECT_H
11 #define LLVM_SUPPORT_MEMORYOBJECT_H
12 
13 #include "llvm/Support/DataTypes.h"
14 
15 namespace llvm {
16 
17 /// Interface to data which might be streamed. Streamability has 2 important
18 /// implications/restrictions. First, the data might not yet exist in memory
19 /// when the request is made. This just means that readByte/readBytes might have
20 /// to block or do some work to get it. More significantly, the exact size of
21 /// the object might not be known until it has all been fetched. This means that
22 /// to return the right result, getExtent must also wait for all the data to
23 /// arrive; therefore it should not be called on objects which are actually
24 /// streamed (this would defeat the purpose of streaming). Instead,
25 /// isValidAddress can be used to test addresses without knowing the exact size
26 /// of the stream. Finally, getPointer can be used instead of readBytes to avoid
27 /// extra copying.
28 class MemoryObject {
29 public:
30  virtual ~MemoryObject();
31 
32  /// Returns the size of the region in bytes. (The region is contiguous, so
33  /// the highest valid address of the region is getExtent() - 1).
34  ///
35  /// @result - The size of the region.
36  virtual uint64_t getExtent() const = 0;
37 
38  /// Tries to read a contiguous range of bytes from the region, up to the end
39  /// of the region.
40  ///
41  /// @param Buf - A pointer to a buffer to be filled in. Must be non-NULL
42  /// and large enough to hold size bytes.
43  /// @param Size - The number of bytes to copy.
44  /// @param Address - The address of the first byte, in the same space as
45  /// getBase().
46  /// @result - The number of bytes read.
47  virtual uint64_t readBytes(uint8_t *Buf, uint64_t Size,
48  uint64_t Address) const = 0;
49 
50  /// Ensures that the requested data is in memory, and returns a pointer to it.
51  /// More efficient than using readBytes if the data is already in memory. May
52  /// block until (address - base + size) bytes have been read
53  /// @param address - address of the byte, in the same space as getBase()
54  /// @param size - amount of data that must be available on return
55  /// @result - valid pointer to the requested data
56  virtual const uint8_t *getPointer(uint64_t address, uint64_t size) const = 0;
57 
58  /// Returns true if the address is within the object (i.e. between base and
59  /// base + extent - 1 inclusive). May block until (address - base) bytes have
60  /// been read
61  /// @param address - address of the byte, in the same space as getBase()
62  /// @result - true if the address may be read with readByte()
63  virtual bool isValidAddress(uint64_t address) const = 0;
64 };
65 
66 }
67 
68 #endif
virtual uint64_t getExtent() const =0
Returns the size of the region in bytes.
Interface to data which might be streamed.
Definition: MemoryObject.h:28
virtual uint64_t readBytes(uint8_t *Buf, uint64_t Size, uint64_t Address) const =0
Tries to read a contiguous range of bytes from the region, up to the end of the region.
virtual bool isValidAddress(uint64_t address) const =0
Returns true if the address is within the object (i.e.
virtual const uint8_t * getPointer(uint64_t address, uint64_t size) const =0
Ensures that the requested data is in memory, and returns a pointer to it.
void size_t size
virtual ~MemoryObject()