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 69
