32 bit makefile into 64 bit makefile


First off I am of the understanding that this question is like asking how long is a piece of string, but here goes.  How would I go about researching how to change a 32 bit program into a 64 bit program.  There is a Ispai Filter called Ionics Isapi Rewrite Engine.  it is great but it is only compatible on 32 bit machines.  The source is there, but how and where would I start to make this compatible with a 64 bit machine?

Thanks in advance,

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jkrConnect With a Mentor Commented:
Go to your project properties, choose 'C/C++', then 'Preprocessor' and add that directory in 'Additional Include Directories'. That should do the job.
If that is for VC++, changing the linker flag






respectively should do the job. Other difficulties may then arise, but that's what to start with.

That's what MS' docs are saying about that:

To copy Win32 project settings into a 64-bit project configuration
When the New Solution Platform dialog box is open while you set up your project to target a 64-bit platform, click the Copy settings from drop-down arrow, and then select Win32. The following project settings are automatically updated on the project level:

/MACHINE (Specify Target Platform) is set to /MACHINE:IA64 or /MACHINE:X64.

Register Output is turned OFF. For more information, see Linker Property Pages.

Target Environment is set to /env x64 or /env ia64. For more information, see MIDL Property Pages: General.

Validate Parameters is cleared and reset to the default value. For more information, see MIDL Property Pages: Advanced.

If Debug Information Format was set to /ZI in the Win32 project configuration, then it is set to /Zi in the 64-bit project configuration. For more information, see /Z7, /Zi, /ZI (Debug Information Format).

Values of WIN32 are replaced by WIN64 for /D (Preprocessor Definitions).

REA_ANDREWAuthor Commented:
Well it seems to have been built with C, I have four source files with the .c extension.  I am creating inside Visual Studio 2008 an empty Win32 Project and in the properties i have set the compiler to be C.  I have added all the header files, but it errors saying it cannot find one of them when it is there.  This header file also has an object library and VS said something about needing to build it?

Cheers for the help.

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You might have to specify a path for the header files - or do they all reside in the same directory?
REA_ANDREWAuthor Commented:
Ahh I see.  Well the one which it cannot find is in another directory with an object file.  Now i created the folder structure inside the solution.  Could you tell me how I could inform the compiler of their location or will it automatically pick that up.  I am thinking it won't as it does not build when i have that speicifc directory structure.


REA_ANDREWAuthor Commented:
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