Package ghidra.program.model.mem

Class WrappedMemBuffer

java.lang.Object

ghidra.program.model.mem.WrappedMemBuffer

All Implemented Interfaces:

MemBuffer

public class WrappedMemBuffer
extends java.lang.Object
implements MemBuffer

WrappedMemBuffer implements a MemBuffer that provides a zero based index on top of an underlying membuffer with at a given address. It can buffer N bytes at time using the constructor that takes a cache size. However the default is to provide no buffering. Use of the buffer can reduce the overall number of calls to Memory, greatly reducing the overhead of various error checks. This implementation will not wrap if the end of the memory space is encountered. The getByte(int), getBytes(byte[], int) methods can cause the bytes in the buffer cache if the request is outside of the current cached bytes. WARNING: The underlying MemBuffer should not change its base address. Using a mutable MemBuffer can cause problematic behavior if not controlled carefully. WARNING: Not thread-safe.

Constructor Summary

Constructors

Constructor	Description
WrappedMemBuffer(MemBuffer buf, int baseOffset)	Construct a wrapped MemBuffer with an adjustable base offset
WrappedMemBuffer(MemBuffer buf, int bufferSize, int baseOffset)	Construct a wrapped MemBuffer with an adjustable base offset

Method Summary

Modifier and Type	Method	Description
Address	getAddress()	Get the Address which corresponds to the offset 0.
java.math.BigInteger	getBigInteger(int offset, int size, boolean signed)	returns the value at the given offset, taking into account the endianess.
byte	getByte(int offset)	Get one byte from memory at the current position plus offset.
int	getBytes(byte[] b, int offset)	Reads b.length bytes from this memory buffer starting at the address of this memory buffer plus the given memoryBufferOffset from that position.
int	getInt(int offset)	returns the int at the given offset, taking into account the endianess.
long	getLong(int offset)	returns the long at the given offset, taking into account the endianess.
Memory	getMemory()	Get the Memory object actually used by the MemBuffer.
short	getShort(int offset)	returns the short at the given offset, taking into account the endianess.
boolean	isBigEndian()	Returns true if the underlying bytes are in big-endian order, false if they are little endian.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface ghidra.program.model.mem.MemBuffer

getUnsignedByte, getUnsignedInt, getUnsignedShort, getVarLengthInt, getVarLengthUnsignedInt, isInitializedMemory

Constructor Detail

WrappedMemBuffer

public WrappedMemBuffer(MemBuffer buf,
                        int baseOffset)
                 throws AddressOutOfBoundsException

Construct a wrapped MemBuffer with an adjustable base offset

Parameters:

buf - memory buffer

baseOffset - offset relative to the underlying buffer's start address (addr + baseOffset) will be the 0 index into this buffer

Throws:

AddressOutOfBoundsException

WrappedMemBuffer

public WrappedMemBuffer(MemBuffer buf,
                        int bufferSize,
                        int baseOffset)
                 throws AddressOutOfBoundsException

Construct a wrapped MemBuffer with an adjustable base offset

Parameters:

buf - memory buffer

bufferSize - size of cache buffer - specify 0 for no buffering

baseOffset - offset relative to the underlying buffer's start address (addr + baseOffset) will be the 0 index into this buffer

Throws:

AddressOutOfBoundsException

Method Detail

getAddress

public Address getAddress()

Description copied from interface: MemBuffer

Get the Address which corresponds to the offset 0.

Specified by:

getAddress in interface MemBuffer

Returns:

the current address of offset 0.

getByte

public byte getByte(int offset)
             throws MemoryAccessException

Description copied from interface: MemBuffer

Get one byte from memory at the current position plus offset.

Specified by:

getByte in interface MemBuffer

Parameters:

offset - the displacement from the current position.

Returns:

the data at offset from the current position.

Throws:

MemoryAccessException - if memory cannot be read at the specified offset

getBytes

public int getBytes(byte[] b,
                    int offset)

Description copied from interface: MemBuffer

Reads b.length bytes from this memory buffer starting at the address of this memory buffer plus the given memoryBufferOffset from that position. The actual number of bytes may be fewer if bytes can't be read.

Specified by:

getBytes in interface MemBuffer

Parameters:

b - the buffer into which bytes will be placed

offset - the offset in this memory buffer from which to start reading bytes.

Returns:

the number of bytes read which may be fewer than b.length if available bytes are exhausted or no bytes are available at the specified offset.

getMemory

public Memory getMemory()

Description copied from interface: MemBuffer

Get the Memory object actually used by the MemBuffer.

Specified by:

getMemory in interface MemBuffer

Returns:

the Memory used by this MemBuffer.

isBigEndian

public boolean isBigEndian()

Description copied from interface: MemBuffer

Returns true if the underlying bytes are in big-endian order, false if they are little endian.

Specified by:

isBigEndian in interface MemBuffer

Returns:

true if the underlying bytes are in big-endian order, false if they are little endian.

getShort

public short getShort(int offset)
               throws MemoryAccessException

Description copied from interface: MemBuffer

returns the short at the given offset, taking into account the endianess.

Specified by:

getShort in interface MemBuffer

Parameters:

offset - the offset from the membuffers origin (the address that it is set at)

Returns:

the short at the given offset, taking into account the endianess.

Throws:

MemoryAccessException - if a 2-byte short value cannot be read at the specified offset

getInt

public int getInt(int offset)
           throws MemoryAccessException

Description copied from interface: MemBuffer

returns the int at the given offset, taking into account the endianess.

Specified by:

getInt in interface MemBuffer

Parameters:

offset - the offset from the membuffers origin (the address that it is set at)

Returns:

the int at the given offset, taking into account the endianess.

Throws:

MemoryAccessException - if a 4-byte integer value cannot be read at the specified offset

getLong

public long getLong(int offset)
             throws MemoryAccessException

Description copied from interface: MemBuffer

returns the long at the given offset, taking into account the endianess.

Specified by:

getLong in interface MemBuffer

Parameters:

offset - the offset from the membuffers origin (the address that it is set at)

Returns:

the long at the given offset, taking into account the endianess.

Throws:

MemoryAccessException - if a 8-byte long value cannot be read at the specified offset

getBigInteger

public java.math.BigInteger getBigInteger(int offset,
                                          int size,
                                          boolean signed)
                                   throws MemoryAccessException

Description copied from interface: MemBuffer

returns the value at the given offset, taking into account the endianess.

Specified by:

getBigInteger in interface MemBuffer

Parameters:

offset - the offset from the membuffers origin (the address that it is set at)

size - the number of bytes to include in the value

signed - true if value should be treated as a signed twos-compliment value.

Returns:

the value at the given offset, taking into account the endianess.

Throws:

MemoryAccessException - if the request size value cannot be read at the specified offset