I thought .NET was supposed to make things easier, if anything, than unmanaged code.
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You don't need multiple native or managed binaries for this. You can just wrap each platform and detect what platform you're on in the .NET runtime via RuntimeInformation class. So you would probably only need one for Win32 and one for POSIX (aka Linux, BSD and macOS). Because a .NET lib doesn't exist for what you need thats portable, you will have to make one that is.
Once again, I cannot map objects to a specific process address space in .NET. No amount of marshalling or unsafe code will change that. It might be possible to create an unmanaged cross compiled library and link to the different calling conventions etc, by conditional P/Invoke, at the cost of extra complexity and adds marshalling to a class that shouldn't have it for perf reasons, and still requiring a cross compiled unmanaged binary and still therefore being limited to certain platforms, not all .NET platforms. So again, it doesn't fulfill the basic requirement because of that latter bit. I accept that it can't be done in .NET
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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Once again, I cannot map objects to a specific process address space in .NET. No amount of marshalling or unsafe code will change that. It might be possible to create an unmanaged cross compiled library and link to the different calling conventions etc, by conditional P/Invoke, at the cost of extra complexity and adds marshalling to a class that shouldn't have it for perf reasons, and still requiring a cross compiled unmanaged binary and still therefore being limited to certain platforms, not all .NET platforms. So again, it doesn't fulfill the basic requirement because of that latter bit. I accept that it can't be done in .NET
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
You said using unsafe code wasn't an issue? So again anything you can do in C can be done in C# if you use unsafe code if thats not an issue to you. It sounds like you don't fully understand what you can do in unsafe code in C#. Cross compiling a native binary would be the same as just using unsafe code in C# and wraping the C methods you need.
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You said using unsafe code wasn't an issue? So again anything you can do in C can be done in C# if you use unsafe code if thats not an issue to you. It sounds like you don't fully understand what you can do in unsafe code in C#. Cross compiling a native binary would be the same as just using unsafe code in C# and wraping the C methods you need.
zezba9000 wrote:
So again anything you can do in C can be done in C# if you use unsafe code
This is categorically incorrect. There is no way to map a .NET object to a file backed portion of the process address space and there likely never will be in .NET. Copying the object to that space or otherwise serializing it is not the same thing at all. I'm going attempt to summarize: You cannot create an object at a specific memory location in managed code.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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zezba9000 wrote:
So again anything you can do in C can be done in C# if you use unsafe code
This is categorically incorrect. There is no way to map a .NET object to a file backed portion of the process address space and there likely never will be in .NET. Copying the object to that space or otherwise serializing it is not the same thing at all. I'm going attempt to summarize: You cannot create an object at a specific memory location in managed code.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
You don't need to if you use pointers in C# just like you would in C. AKA "unsafe code". Unsafe code doesn't require the use of managed objects. Use int* instead of int[] then it will work. More info: Unsafe code and pointers - C# Programming Guide | Microsoft Docs[^]
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You don't need to if you use pointers in C# just like you would in C. AKA "unsafe code". Unsafe code doesn't require the use of managed objects. Use int* instead of int[] then it will work. More info: Unsafe code and pointers - C# Programming Guide | Microsoft Docs[^]
I'm sorry but yes you do if you want that region to be backed by a memory mapped file. otherwise you're just copying/serializing objects into that space at best. to back an object with a memory mapped region of the process address space you'd have to be able to pin an object to a specific address - not really possible in a garbage collected system without some sort of significant work around.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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I'm sorry but yes you do if you want that region to be backed by a memory mapped file. otherwise you're just copying/serializing objects into that space at best. to back an object with a memory mapped region of the process address space you'd have to be able to pin an object to a specific address - not really possible in a garbage collected system without some sort of significant work around.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
No you don't have to copy memory if you use a native pointer to a memory mapped file. In C# a pointer like "int*" is the same as a pointer in C/C++. There is no difference. That pointer in C# will directly be pointing to your native memory buffer you allocated from a native Win32 or POSIX API. Pointers in C# can point to literally anything just as they can in C/C++. That includes managed and unmanaged memory locations. For example this psuedo C# code would work:
[DllImport("nativeLib")]
static unsafe extern int* CreateNativeMemoryMappedFile();unsafe void WriteMemoryMappedFile()
{
int* nativeMemory = CreateNativeMemoryMappedFile();
nativeMemory[0] = 123;// this is writing directly from the native buffer (not a copy)
if (nativeMemory[1] == 321) return;// this is reading directly from the native buffer (not a copy)
} -
No you don't have to copy memory if you use a native pointer to a memory mapped file. In C# a pointer like "int*" is the same as a pointer in C/C++. There is no difference. That pointer in C# will directly be pointing to your native memory buffer you allocated from a native Win32 or POSIX API. Pointers in C# can point to literally anything just as they can in C/C++. That includes managed and unmanaged memory locations. For example this psuedo C# code would work:
[DllImport("nativeLib")]
static unsafe extern int* CreateNativeMemoryMappedFile();unsafe void WriteMemoryMappedFile()
{
int* nativeMemory = CreateNativeMemoryMappedFile();
nativeMemory[0] = 123;// this is writing directly from the native buffer (not a copy)
if (nativeMemory[1] == 321) return;// this is reading directly from the native buffer (not a copy)
}you cannot create objects at that pointer. ergo, no vmem backed objects. you can do pointer ops, but then you're copying object data from the object (on GC heap) to the unmanaged heap. If I do a memcpy, or pointer based assignment in a for loop, either way i'm copying the data. and doing so, even if i did, is really no different than calling (filestream).Write(...) which would be more direct. there is no way around it because of how a GC works. if you think I'm wrong show me how to *create an object* at a specific address in .NET - because that's the only way to back an object with vmem, short of creating a custom CLI host in C(++) or some other unmanaged language and AFAICT would have to back an entire appdomain with vmem for it to work.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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you cannot create objects at that pointer. ergo, no vmem backed objects. you can do pointer ops, but then you're copying object data from the object (on GC heap) to the unmanaged heap. If I do a memcpy, or pointer based assignment in a for loop, either way i'm copying the data. and doing so, even if i did, is really no different than calling (filestream).Write(...) which would be more direct. there is no way around it because of how a GC works. if you think I'm wrong show me how to *create an object* at a specific address in .NET - because that's the only way to back an object with vmem, short of creating a custom CLI host in C(++) or some other unmanaged language and AFAICT would have to back an entire appdomain with vmem for it to work.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
"
Quote:
if you think I'm wrong show me how to *create an object* at a specific address in .NET
Invoke the C method from C# you would use to allocation memory at that specific vmem address. Keep a reference to that address in C# as a pointer as you would in C. No difference from doing it in C. Again if you can address it in C you can address it in C# using pointers. Can you show me what method you're invoking in C that allocates memory at a specific address? Then I can give an example and it would remove the confusion. I can only guess at what methods you're trying to use.
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"
Quote:
if you think I'm wrong show me how to *create an object* at a specific address in .NET
Invoke the C method from C# you would use to allocation memory at that specific vmem address. Keep a reference to that address in C# as a pointer as you would in C. No difference from doing it in C. Again if you can address it in C you can address it in C# using pointers. Can you show me what method you're invoking in C that allocates memory at a specific address? Then I can give an example and it would remove the confusion. I can only guess at what methods you're trying to use.
what C method? the method to create the object? that's not a .NET object. I can already do all this mapping in C. There's no point in any of that.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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"
Quote:
if you think I'm wrong show me how to *create an object* at a specific address in .NET
Invoke the C method from C# you would use to allocation memory at that specific vmem address. Keep a reference to that address in C# as a pointer as you would in C. No difference from doing it in C. Again if you can address it in C you can address it in C# using pointers. Can you show me what method you're invoking in C that allocates memory at a specific address? Then I can give an example and it would remove the confusion. I can only guess at what methods you're trying to use.
you do understand that paged memory allows you to do pointer ops directly to a file, i assume? and that normally what you'd do is just create your data structures at that memory mapped address and then use them like normal classes and structure, which are automatically written to disk as they are accessed.
struct foo {
int bar;
};foo* pfoo = VirtualAlloc(..., sizeof(foo));
pfoo->bar=1; // writes to disk
printf("%d",pfoo->bar); // reads from disk.there is simply no way to do that in .NET if you're saying there is show me how. Your method call technique does not enable this.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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you do understand that paged memory allows you to do pointer ops directly to a file, i assume? and that normally what you'd do is just create your data structures at that memory mapped address and then use them like normal classes and structure, which are automatically written to disk as they are accessed.
struct foo {
int bar;
};foo* pfoo = VirtualAlloc(..., sizeof(foo));
pfoo->bar=1; // writes to disk
printf("%d",pfoo->bar); // reads from disk.there is simply no way to do that in .NET if you're saying there is show me how. Your method call technique does not enable this.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
lol yes there is. You didn't read anything I said. As I said before. C# pointers are the same as C/C++. Look at the example below. I literally just compiled and ran this on my computer with zero errors.
using System;
using System.Runtime.InteropServices;using SIZE_T = System.IntPtr;
using DWORD = System.UInt32;namespace TestNet
{
[StructLayout(LayoutKind.Sequential)]
struct Foo
{
public int bar;
}static class Program { \[DllImport("Kernel32.dll")\] private static unsafe extern void\* VirtualAlloc(void\* lpAddress, SIZE\_T dwSize, DWORD flAllocationType, DWORD flProtect); private const DWORD MEM\_COMMIT = 0x00001000; private const DWORD PAGE\_READWRITE = 0x04; static unsafe void Main(string\[\] args) { Foo\* pfoo = (Foo\*)VirtualAlloc((void\*)0, (SIZE\_T)sizeof(Foo), MEM\_COMMIT, PAGE\_READWRITE); pfoo->bar = 1; // writes to disk Console.WriteLine(pfoo->bar.ToString()); // reads from disk. } }}
Make a C# console app and paste that code in. WaLa!!
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lol yes there is. You didn't read anything I said. As I said before. C# pointers are the same as C/C++. Look at the example below. I literally just compiled and ran this on my computer with zero errors.
using System;
using System.Runtime.InteropServices;using SIZE_T = System.IntPtr;
using DWORD = System.UInt32;namespace TestNet
{
[StructLayout(LayoutKind.Sequential)]
struct Foo
{
public int bar;
}static class Program { \[DllImport("Kernel32.dll")\] private static unsafe extern void\* VirtualAlloc(void\* lpAddress, SIZE\_T dwSize, DWORD flAllocationType, DWORD flProtect); private const DWORD MEM\_COMMIT = 0x00001000; private const DWORD PAGE\_READWRITE = 0x04; static unsafe void Main(string\[\] args) { Foo\* pfoo = (Foo\*)VirtualAlloc((void\*)0, (SIZE\_T)sizeof(Foo), MEM\_COMMIT, PAGE\_READWRITE); pfoo->bar = 1; // writes to disk Console.WriteLine(pfoo->bar.ToString()); // reads from disk. } }}
Make a C# console app and paste that code in. WaLa!!
i'm going to try that. Assuming it works, I apologize for all the churn. You may have just taught my stubborn self something. the example really helped, so thank you.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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i'm going to try that. Assuming it works, I apologize for all the churn. You may have just taught my stubborn self something. the example really helped, so thank you.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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it's mixed mode, as I understand it. Managed *and* unmanaged in the same PE. So it's not simply a .NET assembly but an assembly with a bag on the side of unmanaged code. I'm certain this was true when it was introduced. It probably still is. also i think there's still marshalling going on with managed->unmanaged calls in C++/CLI it might be more efficient than the standard marshalling though, but it's still marshalling.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
#SupportHeForShe Government can give you nothing but what it takes from somebody else. A government big enough to give you everything you want is big enough to take everything you've got, including your freedom.-Ezra Taft Benson You must accept 1 of 2 basic premises: Either we are alone in the universe or we are not alone. Either way, the implications are staggering!-Wernher von Braun
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#SupportHeForShe Government can give you nothing but what it takes from somebody else. A government big enough to give you everything you want is big enough to take everything you've got, including your freedom.-Ezra Taft Benson You must accept 1 of 2 basic premises: Either we are alone in the universe or we are not alone. Either way, the implications are staggering!-Wernher von Braun
yeah thanks. Though what zebra006 (sp?) showed me was more what I was after. Either way, it gives me a starting point.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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honey the codewitch wrote:
Nobody made you respond to me.
If you're a nobody, then yes.
honey the codewitch wrote:
Now I'm blocking you so I don't have to listen to this anymore.
TMI - I don't need to know what you are doing on the internet.
No reason to be an asshole.
#SupportHeForShe Government can give you nothing but what it takes from somebody else. A government big enough to give you everything you want is big enough to take everything you've got, including your freedom.-Ezra Taft Benson You must accept 1 of 2 basic premises: Either we are alone in the universe or we are not alone. Either way, the implications are staggering!-Wernher von Braun
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I said they don't work how they are supposed to. How they were designed was to map files to a process address space so you could do pointer ops to read and write files. That is not doable under .NET. Sorry I've just explained this a lot. If you've used memory mapped files in unmanaged code then you know what i'm talking about. Otherwise you might never. I don't know. You cannot do var foo = new int[100000]; //backed by file. That's how it's supposed to work. It can't under .NET
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
honey the codewitch wrote:
It can't under .NET
not even with "unsafe"?
#SupportHeForShe Government can give you nothing but what it takes from somebody else. A government big enough to give you everything you want is big enough to take everything you've got, including your freedom.-Ezra Taft Benson You must accept 1 of 2 basic premises: Either we are alone in the universe or we are not alone. Either way, the implications are staggering!-Wernher von Braun
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lol yes there is. You didn't read anything I said. As I said before. C# pointers are the same as C/C++. Look at the example below. I literally just compiled and ran this on my computer with zero errors.
using System;
using System.Runtime.InteropServices;using SIZE_T = System.IntPtr;
using DWORD = System.UInt32;namespace TestNet
{
[StructLayout(LayoutKind.Sequential)]
struct Foo
{
public int bar;
}static class Program { \[DllImport("Kernel32.dll")\] private static unsafe extern void\* VirtualAlloc(void\* lpAddress, SIZE\_T dwSize, DWORD flAllocationType, DWORD flProtect); private const DWORD MEM\_COMMIT = 0x00001000; private const DWORD PAGE\_READWRITE = 0x04; static unsafe void Main(string\[\] args) { Foo\* pfoo = (Foo\*)VirtualAlloc((void\*)0, (SIZE\_T)sizeof(Foo), MEM\_COMMIT, PAGE\_READWRITE); pfoo->bar = 1; // writes to disk Console.WriteLine(pfoo->bar.ToString()); // reads from disk. } }}
Make a C# console app and paste that code in. WaLa!!
Thanks for sticking with it and being nice and teaching us all something new. :)
#SupportHeForShe Government can give you nothing but what it takes from somebody else. A government big enough to give you everything you want is big enough to take everything you've got, including your freedom.-Ezra Taft Benson You must accept 1 of 2 basic premises: Either we are alone in the universe or we are not alone. Either way, the implications are staggering!-Wernher von Braun
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yeah thanks. Though what zebra006 (sp?) showed me was more what I was after. Either way, it gives me a starting point.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
ah yes, his example[^] is more succinct
#SupportHeForShe Government can give you nothing but what it takes from somebody else. A government big enough to give you everything you want is big enough to take everything you've got, including your freedom.-Ezra Taft Benson You must accept 1 of 2 basic premises: Either we are alone in the universe or we are not alone. Either way, the implications are staggering!-Wernher von Braun
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ah yes, his example[^] is more succinct
#SupportHeForShe Government can give you nothing but what it takes from somebody else. A government big enough to give you everything you want is big enough to take everything you've got, including your freedom.-Ezra Taft Benson You must accept 1 of 2 basic premises: Either we are alone in the universe or we are not alone. Either way, the implications are staggering!-Wernher von Braun
i love it when i learn stuff, even if i have to be dragged to it. I'm only curious if this worked in early .NET and I just missed it before, or if it's a byproduct of me dropping development for years and only recently playing catch up.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.