RawPointer

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`RawPointer`

[Experimental]

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RawPointer[addr,type]

represents a raw pointer to the specified type at the memory address addr.

Details

RawPointer is returned by functions such as ForeignFunction, RawMemoryAllocate, etc.
Functions that allocate raw memory will return a memory-managed pointer.
OpaqueRawPointer can be used to represent untyped pointers.
RawPointer[ptr,type] can be used to cast a pointer to a typed pointer.
Information for a RawPointer may include the following properties:
"Address" memory address

"Type" referenced type
Properties of a RawPointer can be extracted with RawPointer[…][prop].
Properties that can be extracted include all Information properties listed above.

Examples

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Basic Examples (1)Summary of the most common use cases

Export a string as raw memory represented by a managed RawPointer:

In[1]:=1

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https://wolfram.com/xid/0rs5u6a3a-cbzwp4

Out[2]=2

Unmanage the pointer:

In[3]:=3

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https://wolfram.com/xid/0rs5u6a3a-stb323

Out[3]=3

Write a value to the raw memory:

In[4]:=4

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https://wolfram.com/xid/0rs5u6a3a-feaufq

Import the raw memory as a string:

In[5]:=5

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https://wolfram.com/xid/0rs5u6a3a-2y6xxp

Out[5]=5

Free the raw memory:

In[6]:=6

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https://wolfram.com/xid/0rs5u6a3a-xo1vps

Scope (1)Survey of the scope of standard use cases

Information (1)

Create a pointer to raw memory:

In[1]:=1

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https://wolfram.com/xid/0rs5u6a3a-foy396

Out[1]=1

Get Information about the pointer:

In[2]:=2

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https://wolfram.com/xid/0rs5u6a3a-mffoz6

Out[2]=2

Get the memory address of the pointer:

In[3]:=3

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https://wolfram.com/xid/0rs5u6a3a-j20rsp

Out[3]=3

Get the type of the pointer:

In[4]:=4

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https://wolfram.com/xid/0rs5u6a3a-jqd047

Out[4]=4

Properties & Relations (5)Properties of the function, and connections to other functions

Functions like RawMemoryAllocate return a memory-managed RawPointer:

In[1]:=1

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https://wolfram.com/xid/0rs5u6a3a-t7oo94

Out[1]=1

Call UnmanageObject to take ownership of the managed pointer:

In[2]:=2

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https://wolfram.com/xid/0rs5u6a3a-s4u1o3

Out[2]=2

Notice that the memory management of the pointer allocated is no longer active:

In[3]:=3

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https://wolfram.com/xid/0rs5u6a3a-nym11z

Out[3]=3

Unmanaged pointers should be freed with RawMemoryFree to avoid memory leaks:

In[4]:=4

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https://wolfram.com/xid/0rs5u6a3a-fpucx3

NullRawPointerQ returns True if a raw pointer has 0 as its address:

In[1]:=1

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https://wolfram.com/xid/0rs5u6a3a-o7h4us

Out[1]=1

Allocate some raw memory:

In[1]:=1

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https://wolfram.com/xid/0rs5u6a3a-0ksk2u

Out[1]=1

Convert a RawPointer into an OpaqueRawPointer:

In[2]:=2

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https://wolfram.com/xid/0rs5u6a3a-38texn

Out[2]=2

Convert the opaque raw pointer back to a RawPointer:

In[3]:=3

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https://wolfram.com/xid/0rs5u6a3a-127kwl

Out[3]=3

Allocate a raw memory for an object of type "UnsignedInteger8":

In[1]:=1

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https://wolfram.com/xid/0rs5u6a3a-5tx94m

Out[1]=1

Write a value to the raw memory by passing the pointer to RawMemoryWrite:

In[2]:=2

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https://wolfram.com/xid/0rs5u6a3a-ltumwt

Out[2]=2

Read the raw memory with RawMemoryRead:

In[3]:=3

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https://wolfram.com/xid/0rs5u6a3a-9me5i8

Out[3]=3

Allocate a buffer of 10 "CLong" objects:

In[1]:=1

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https://wolfram.com/xid/0rs5u6a3a-bqm82s

Out[1]=1

Use ForeignFunctionLoad to load a function that populates this buffer:

In[2]:=2

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https://wolfram.com/xid/0rs5u6a3a-ngv0o5

Out[2]=2

Call the function by passing the buffer and its length:

In[3]:=3

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https://wolfram.com/xid/0rs5u6a3a-2in6km

Import the raw memory as a list with RawMemoryImport:

In[4]:=4

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https://wolfram.com/xid/0rs5u6a3a-0o98hw

Out[4]=4

Possible Issues (1)Common pitfalls and unexpected behavior

RawPointer returns a Failure for invalid memory addresses:

In[1]:=1

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https://wolfram.com/xid/0rs5u6a3a-swz10k

Out[1]=1

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